2024-03-28T15:55:49Zhttps://www.repo.uni-hannover.de/oai/requestoai:www.repo.uni-hannover.de:123456789/472022-12-02T16:17:36Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610
Cochlear Dummy Electrodes for Insertion Training and Research Purposes: Fabrication, Mechanical Characterization, and Experimental Validation
Kobler, Jan-Philipp
Dhanasingh, Anandhan
Kiran, Raphael
Jolly, Claude
Ortmaier, Tobias
Otolaryngology
Cochlear implant
surgery
cochlear implant surgery
cochlear electrodes
Electrodes
Cochlear Implantat
Hals-Nasen-Ohren-Heilkunde
Chirurgie
Elekroden
ddc:610
Hals-Nasen-Ohren-Chirurgie
Cochlear-Implantat
Elektrode
To develop skills sufficient for hearing preservation cochlear implant surgery, surgeons need to performseveral electrode insertion trials in ex vivo temporal bones, thereby consuming relatively expensive electrode carriers. The objectives of this study were to evaluate the insertion characteristics of cochlear electrodes in a plastic scala tympani model and to fabricate radio opaque polymer filament dummy electrodes of equivalent mechanical properties. In addition, this study should aid the design and development of new cochlear electrodes. Automated insertion force measurement is a new technique to reproducibly analyze and evaluate the insertion dynamics and mechanical characteristics of an electrode. Mechanical properties of MED-EL’s FLEX28, FLEX24, and FLEX20 electrodes were assessed with the help of an automated insertion tool. Statistical analysis of the overall mechanical behavior of the electrodes and factors influencing the insertion force are discussed. Radio opaque dummy electrodes of comparable characteristics were fabricated based on insertion force measurements. The platinum-iridium wires were replaced by polymer filament to provide sufficient stiffness to the electrodes and to eradicate the metallic artifacts in X-ray and computed tomography (CT) images. These low-cost dummy electrodes are cheap alternatives for surgical training and for in vitro, ex vivo, and in vivo research purposes.
DFG
status-type:publishedVersion
New York [u.a.] : Hindawi Publishing Corporation
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/29
http://www.repo.uni-hannover.de/handle/123456789/47
DOI:http://dx.doi.org/10.1155/2015/574209
ISSN:2314-6133
ESSN:2314-6141
BioMed Research International 2015 (2015), Nr. 5
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/582022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600ddc:500
Encapsulating Non-Human Primate Multipotent Stromal Cells in Alginate via High Voltage for Cell-Based Therapies and Cryopreservation
Gryshkov, Oleksandr
Pogozhykh, Denys
Hofmann, Nicola
Pogozhykh, Olena
Müller, Thomas
Glasmacher, Birgit
Cross-linking
Cryopreservation
Marmoset
Air flow
Cell staining
Amnion
Flow rate
Cell differentiation
Vernetzung
Kryokonservierung
Callithrix jacchus
Weißbüschelaffe
Marmosetten
Luftstrom
Zellfärbung
Amnion
Flussrate
Durchsatz
ddc:500
ddc:600
Vernetzung <Chemie>
Kryokonservierung
Zelldifferenzierung
Weißbüscheläffchen
Marmoset
Luftstrom
Amnion
Durchfluss
Alginate cell-based therapy requires further development focused on clinical application. To assess engraftment, risk of mutations and therapeutic benefit studies should be performed in an appropriate non-human primate model, such as the common marmoset (Callithrix jacchus). In this work we encapsulated amnion derived multipotent stromal cells (MSCs) from Callithrix jacchus in defined size alginate beads using a high voltage technique. Our results indicate that i) alginate-cell mixing procedure and cell concentration do not affect the diameter of alginate beads, ii) encapsulation of high cell numbers (up to 10×106 cells/ml) can be performed in alginate beads utilizing high voltage and iii) high voltage (15–30 kV) does not alter the viability, proliferation and differentiation capacity of MSCs post-encapsulation compared with alginate encapsulated cells produced by the traditional air-flow method. The consistent results were obtained over the period of 7 days of encapsulated MSCs culture and after cryopreservation utilizing a slow cooling procedure (1 K/min). The results of this work show that high voltage encapsulation can further be maximized to develop cell-based therapies with alginate beads in a non-human primate model towards human application.
DFG/EXC/62/1
status-type:publishedVersion
San Francisco : Public Library of Science
2014-09-26
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/40
http://www.repo.uni-hannover.de/handle/123456789/58
http://dx.doi.org/10.1371/journal.pone.0107911.g001
http://dx.doi.org/10.1371/journal.pone.0107911.g002
http://dx.doi.org/10.1371/journal.pone.0107911.g003
http://dx.doi.org/10.1371/journal.pone.0107911.g004
http://dx.doi.org/10.1371/journal.pone.0107911.g005
http://dx.doi.org/10.1371/journal.pone.0107911.g006
http://dx.doi.org/10.1371/journal.pone.0107911.g007
http://dx.doi.org/10.1371/journal.pone.0107911.s001
http://dx.doi.org/10.1371/journal.pone.0107911.s002
DOI:http://dx.doi.org/10.1371/journal.pone.0107911
ISSN:1932-6203
PLoS ONE 9 (2014), Nr. 9
eng
CC BY 4.0 Unported
http://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/1212022-12-02T16:17:36Zcom_123456789_1col_123456789_6doc-type:Reportdoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Manufacturing and Characterization of Paper-Based Magnetic Coatings : Projects in Engineering and Science Summer 2015
Steggeman, Matthew
Akin, Meriem
Rissing, Lutz
Paper magnetics
Smart paper
Paper-based systems
Papier-basierte Systeme
Intelligentes Papier
Papierbasierte Systeme
Papierbasiertes System
ddc:600
ddc:620
Elektronisches Papier
Papier
System
Magnetismus
Employing paper as an engineering material is emerging in industry today. Paper-based technology has grown in the last several years. Current technology includes, but is not limited to, foldable paper microscopes, a disk jockey board made from paper, and interactive wallpapers and newspapers. In terms of magnetic paper-based devices, these systems are limited to the use of hard magnetic materials for bitwise writing and reading, and actuating. At the Institute of Micro-Production Technology, embedding soft magnetic materials into the paper itself is being researched to enable a novel paper-based technology such as spintronic devices. This report will show the details of the ongoing research of the characteristics and properties of soft magnetic coatings on paper-based substrates.
status-type:publishedVersion
Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
2015-11-09
doc-type:Report
doc-type:Text
http://dx.doi.org/10.15488/103
http://www.repo.uni-hannover.de/handle/123456789/121
eng
CC BY-NC-ND 3.0 DE
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/1242022-12-02T16:17:36Zcom_123456789_1col_123456789_6doc-type:BachelorThesisdoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Experimentelle Entwicklung von Bondprozessen mit niedrigschmelzenden eutektischen Legierungen auf flexiblen Substraten mit niedriger Glasübergangstemperatur
Moakhar ep Bouguecha, Sonda
Meriem Akin
Rittinger, Johannes
Rissing, Lutz
Leibniz Universität Hannover. Institut für Mikroproduktionstechnik
Behrens, Bernd-Arno
Low temperature
eutectic bonding
Polymer
Eutektisches Bonden
Polymer
Niedrigtemperatur
ddc:620
ddc:621,3
Bonden
Eutektische Legierung
Polymere
Niedrigtemperatur
Das übergeordnete Ziel dieser Arbeit besteht in der Grundlagenuntersuchung und Optimierung von eutektischen Bondprozessen (auch Anlegieren genannt) für die Befestigung von elektronischen Bauteilen auf flexiblen Substraten. In diesem Zusammenhang sind umfangreiche experimentelle Untersuchungen und zahlreiche Parametervariationen vorgesehen um möglichst stabile mechanische und elektrische Bondverbindung zwischen den Fügepartnern zu erreichen. Dafür werden Chips aus Silizium zunächst auf starren und dann auf flexiblen Substraten durch Anlegieren verbunden. Um eine zuverlässige Bondverbindung auf flexiblen Substraten mit niedrigen Glasübergangstemperaturen zu erzielen, werden die eutektischen Indium-Zinn- und Indium-Bismut-Legierungen zum Einsatz kommen. Die experimentelle Methodik basiert auf der Variation der Bondprozessparameter: Temperatur, Druck und Dauer um die Bondverbindung insbesondere hinsichtlich der mechanischen Stabilität zu optimieren. Hierbei wird diese durch die Scherfestigkeit beurteilt. Ferner wurde ebenfalls der elektrische Widerstand der Verbindung gemessen um die elektrische Eigenschaft der Verbindung zu bewerten.
status-type:publishedVersion
Hannover : Gottfried Wilhelm Leibniz Universität Hannover
2015-11-13
doc-type:BachelorThesis
doc-type:Text
http://dx.doi.org/10.15488/106
http://www.repo.uni-hannover.de/handle/123456789/124
ger
CC BY-NC-ND 3.0 DE
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4132022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Non-contact test set-up for aeroelasticity in a rotating turbomachine combining a novel acoustic excitation system with tip-timing
Freund, O.
Montgomery, M.
Mittelbach, M.
Seume, Jörg R.
aeroelasticity
acoustic excitation
tip-timing
ddc:620
Due to trends in aero-design, aeroelasticity becomes increasingly important in modern turbomachines. Design requirements of turbomachines lead to the development of high aspect ratio blades and blade integral disc designs (blisks), which are especially prone to complex modes of vibration. Therefore, experimental investigations yielding high quality data are required for improving the understanding of aeroelastic effects in turbomachines. One possibility to achieve high quality data is to excite and measure blade vibrations in turbomachines. The major requirement for blade excitation and blade vibration measurements is to minimize interference with the aeroelastic effects to be investigated. Thus in this paper, a non-contact-and thus low interference-experimental set-up for exciting and measuring blade vibrations is proposed and shown to work. A novel acoustic system excites rotor blade vibrations, which are measured with an optical tip-timing system. By performing measurements in an axial compressor, the potential of the acoustic excitation method for investigating aeroelastic effects is explored. The basic principle of this method is described and proven through the analysis of blade responses at different acoustic excitation frequencies and at different rotational speeds. To verify the accuracy of the tip-timing system, amplitudes measured by tip-timing are compared with strain gage measurements. They are found to agree well. Two approaches to vary the nodal diameter (ND) of the excited vibration mode by controlling the acoustic excitation are presented. By combining the different excitable acoustic modes with a phase-lag control, each ND of the investigated 30 blade rotor can be excited individually. This feature of the present acoustic excitation system is of great benefit to aeroelastic investigations and represents one of the main advantages over other excitation methods proposed in the past. In future studies, the acoustic excitation method will be used to investigate aeroelastic effects in high-speed turbomachines in detail. The results of these investigations are to be used to improve the aeroelastic design of modern turbomachines.
Siemens Energy
DFG/SFB/871
status-type:publishedVersion
Bristol : IOP Publishing Ltd.
2014-03
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/390
http://www.repo.uni-hannover.de/handle/123456789/413
DOI:http://dx.doi.org/10.1088/0957-0233/25/3/035008
ISSN:0957-0233
ESSN:1361-6501
Measurement Science & Technology 25 (2014), Nr. 3
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4342022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Effect of Geometric Uncertainties on the Aerodynamic Characteristic of Offshore Wind Turbine Blades
Ernst, Benedikt
Schmitt, Henning
Seume, Jörg R.
design
ddc:620
Konferenzschrift
Offshore wind turbines operate in a complex unsteady flow environment which causes unsteady aerodynamic loads. The unsteady flow environment is characterized by a high degree of uncertainty. In addition, geometry variations and material imperfections also cause uncertainties in the design process. Probabilistic design methods consider these uncertainties in order to reach acceptable reliability and safety levels for offshore wind turbines. Variations of the rotor blade geometry influence the aerodynamic loads which also affect the reliability of other wind turbine components. Therefore, the present paper is dealing with geometric uncertainties of the rotor blades. These can arise from manufacturing tolerances and operational wear of the blades. First, the effect of geometry variations of wind turbine airfoils on the lift and drag coefficients are investigated using a Latin hypercube sampling. Then, the resulting effects on the performance and the blade loads of an offshore wind turbine are analyzed. The variations of the airfoil geometry lead to a significant scatter of the lift and drag coefficients which also affects the damage-equivalent flapwise bending moments. In contrast to that, the effects on the power and the annual energy production are almost negligible with regard to the assumptions made.
Ministry for Science and Culture in Lower Saxony/ForWind
status-type:publishedVersion
Bristol : IOP Publishing Ltd.
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/411
http://www.repo.uni-hannover.de/handle/123456789/434
DOI:http://dx.doi.org/10.1088/1742-6596/555/1/012033
ISSN:1742-6588
ESSN:1742-6596
Journal of Physics Conference Series 534 (2014)
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4372022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Wind turbine rotor blade monitoring using digital image correlation: a comparison to aeroelastic simulations of a multi-megawatt wind turbine
Winstroth, J.
Schoen, L.
Ernst, Benedikt
Seume, Jörg R.
Energy & Fuels
Engineering, Mechanical
Physics, Applied
ddc:620
Konferenzschrift
Optical full-field measurement methods such as Digital Image Correlation (DIC) provide a new opportunity for measuring deformations and vibrations with high spatial and temporal resolution. However, application to full-scale wind turbines is not trivial. Elaborate preparation of the experiment is vital and sophisticated post processing of the DIC results essential. In the present study, a rotor blade of a 3.2 MW wind turbine is equipped with a random black-and-white dot pattern at four different radial positions. Two cameras are located in front of the wind turbine and the response of the rotor blade is monitored using DIC for different turbine operations. In addition, a Light Detection and Ranging (LiDAR) system is used in order to measure the wind conditions. Wind fields are created based on the LiDAR measurements and used to perform aeroelastic simulations of the wind turbine by means of advanced multibody codes. The results from the optical DIC system appear plausible when checked against common and expected results. In addition, the comparison of relative out-of-plane blade deflections shows good agreement between DIC results and aeroelastic simulations.
Ministry of Science and Culture of Lower Saxony
status-type:publishedVersion
Bristol : IOP Publishing Ltd.
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/414
http://www.repo.uni-hannover.de/handle/123456789/437
DOI:http://dx.doi.org/10.1088/1742-6596/524/1/012064
ISSN:1742-6588
ESSN:1742-6596
Journal of Physics Conference Series 524 (2014)
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4382022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Aerodynamic behavior of an airfoil with morphing trailing edge for wind turbine applications
Wolff, T.
Ernst, Benedikt
Seume, Jörg R.
Energy & Fuels
Engineering, Mechanical
Physics, Applied
ddc:620
Konferenzschrift
The length of wind turbine rotor blades has been increased during the last decades. Higher stresses arise especially at the blade root because of the longer lever arm. One way to reduce unsteady blade-root stresses caused by turbulence, gusts, or wind shear is to actively control the lift in the blade tip region. One promising method involves airfoils with morphing trailing edges to control the lift and consequently the loads acting on the blade. In the present study, the steady and unsteady behavior of an airfoil with a morphing trailing edge is investigated. Two-dimensional Reynolds-Averaged Navier-Stokes (RANS) simulations are performed for a typical thin wind turbine airfoil with a morphing trailing edge. Steady-state simulations are used to design optimal geometry, size, and deflection angles of the morphing trailing edge. The resulting steady aerodynamic coefficients are then analyzed at different angles of attack in order to determine the effectiveness of the morphing trailing edge. In order to investigate the unsteady aerodynamic behavior of the optimal morphing trailing edge, time-resolved RANS-simulations are performed using a deformable grid. In order to analyze the phase shift between the variable trailing edge deflection and the dynamic lift coefficient, the trailing edge is deflected at four different reduced frequencies for each different angle of attack. As expected, a phase shift between the deflection and the lift occurs. While deflecting the trailing edge at angles of attack near stall, additionally an overshoot above and beyond the steady lift coefficient is observed and evaluated.
BMWi/Smart Blades
German Aerospace Center (DLR)
LUIS
status-type:publishedVersion
Bristol : IOP Publishing Ltd.
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/415
http://www.repo.uni-hannover.de/handle/123456789/438
DOI:http://dx.doi.org/10.1088/1742-6596/524/1/012018
ISSN:1742-6588
ESSN:1742-6596
Journal of Physics Conference Series 524 (2014)
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4592022-12-02T18:18:52Zcom_123456789_1col_123456789_6doc-type:BachelorThesisdoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Evaluation and FMEA of Fabrication Techniques for Metallic Grating Couplers on Polymer Substrates with Low Glass Transition Temperatures
Gribaa, Wejdene
Akin, Meriem
Grating couplers
Fabrication
Polymeric devices
Gitterkoppler
Optische Sensorik
Produktion
Polymere
ddc:620
Polymere
Gitterkoppler
Sensortechnik
Werkstoffkunde
Produktionstechnik
The main task is to analyze the state of the art of grating couplers production and low-cost polymer substrates. Then to provide a recommendation of a new or adapted process for the production of metallic gratings on polymer sheets, based on a Failure Mode and Effect Analysis (FMEA). In order to achieve that, this thesis is divided into four chapters. After the first introductory chapter, the second section provides details about the state-of-the-art in optical technology platforms with focus on polymers and their main features for the aimed application, such as flexibility, low cost and roll to roll compatibility. It defines then the diffraction gratings and their specifications and closes with the explanation of adhesion mechanisms of inorganic materials on polymer substrates. The third chapter discusses processing of grating couplers. It introduces the basic fabrication methods and details a selection of current fabrication schemes found in literature with an assessment of their potential use for the desired application. The last chapter is a FMEA analysis of the retained fabrication process, called Flip and Fuse, in order to check its capability to realize the grating structure.
status-type:publishedVersion
Hannover : Gottfried Wilhelm Leibniz Universität Hannover
2016-08-25
doc-type:BachelorThesis
doc-type:Text
http://dx.doi.org/10.15488/436
http://www.repo.uni-hannover.de/handle/123456789/459
eng
CC BY 3.0 DE
https://creativecommons.org/licenses/by/3.0/de/
http://creativecommons.org/licenses/by/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4732022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Influence of Cobalt on the Properties of Load-Sensitive Magnesium Alloys
Klose, Christian
Demminger, Christian
Mroz, Gregor
Reimche, Wilfried
Bach, Friedrich-Wilhelm
Maier, Hans Jürgen
Kerber, Kai
physical sensors
magnetic materials
load-sensitive materials
villari effect
magnesium
cobalt
ddc:620
In this study, magnesium is alloyed with varying amounts of the ferromagnetic alloying element cobalt in order to obtain lightweight load-sensitive materials with sensory properties which allow an online-monitoring of mechanical forces applied to components made from Mg-Co alloys. An optimized casting process with the use of extruded Mg-Co powder rods is utilized which enables the production of magnetic magnesium alloys with a reproducible Co concentration. The efficiency of the casting process is confirmed by SEM analyses. Microstructures and Co-rich precipitations of various Mg-Co alloys are investigated by means of EDS and XRD analyses. The Mg-Co alloys' mechanical strengths are determined by tensile tests. Magnetic properties of the Mg-Co sensor alloys depending on the cobalt content and the acting mechanical load are measured utilizing the harmonic analysis of eddy-current signals. Within the scope of this work, the influence of the element cobalt on magnesium is investigated in detail and an optimal cobalt concentration is defined based on the performed examinations.
DFG/Collaborative Research Center 653/Subproject E2
DFG/CRC/653
status-type:publishedVersion
Basel : Mdpi Ag
2013-01
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/450
http://www.repo.uni-hannover.de/handle/123456789/473
DOI:http://dx.doi.org/10.3390/s130100106
ISSN:1424-8220
Sensors 13 (2013), Nr. 1
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4812022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Numerical simulation of strain-adaptive bone remodelling in the ankle joint
Bouguecha, Anas
Weigel, Nelly
Behrens, Bernd-Arno
Stukenborg-Colsman, Christina
Waizy, Hazibullah
finite-element-analysis
gait analysis
stance phase
arthroplasty
replacement
mechanics
forces
arthrodesis
management
prostheses
ddc:620
Background: The use of artificial endoprostheses has become a routine procedure for knee and hip joints while ankle arthritis has traditionally been treated by means of arthrodesis. Due to its advantages, the implantation of endoprostheses is constantly increasing. While finite element analyses (FEA) of strain-adaptive bone remodelling have been carried out for the hip joint in previous studies, to our knowledge there are no investigations that have considered remodelling processes of the ankle joint. In order to evaluate and optimise new generation implants of the ankle joint, as well as to gain additional knowledge regarding the biomechanics, strain-adaptive bone remodelling has been calculated separately for the tibia and the talus after providing them with an implant. Methods: FE models of the bone-implant assembly for both the tibia and the talus have been developed. Bone characteristics such as the density distribution have been applied corresponding to CT scans. A force of 5,200 N, which corresponds to the compression force during normal walking of a person with a weight of 100 kg according to Stauffer et al., has been used in the simulation. The bone adaptation law, previously developed by our research team, has been used for the calculation of the remodelling processes. Results: A total bone mass loss of 2% in the tibia and 13% in the talus was calculated. The greater decline of density in the talus is due to its smaller size compared to the relatively large implant dimensions causing remodelling processes in the whole bone tissue. In the tibia, bone remodelling processes are only calculated in areas adjacent to the implant. Thus, a smaller bone mass loss than in the talus can be expected. There is a high agreement between the simulation results in the distal tibia and the literature regarding. Conclusions: In this study, strain-adaptive bone remodelling processes are simulated using the FE method. The results contribute to a better understanding of the biomechanical behaviour of the ankle joint and hence are useful for the optimisation of the implant geometry in the future.
status-type:publishedVersion
London : Biomed Central Ltd
2011-07-05
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/458
http://www.repo.uni-hannover.de/handle/123456789/481
DOI:http://dx.doi.org/10.1186/1475-925X-10-58
ISSN:1475-925X
Biomedical Engineering Online 10 (2011)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4902022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Multi-body simulation of a canine hind limb: model development, experimental validation and calculation of ground reaction forces
Helms, Gabriele
Behrens, Bernd-Arno
Stolorz, Martin
Wefstaedt, Patrick
Nolte, Ingo
total hip prostheses
gait analysis
numerical investigations
contact mechanics
healthy dogs
trot
replacement
treadmill
walking
stress
ddc:620
Background: Among other causes the long-term result of hip prostheses in dogs is determined by aseptic loosening. A prevention of prosthesis complications can be achieved by an optimization of the tribological system which finally results in improved implant duration. In this context a computerized model for the calculation of hip joint loadings during different motions would be of benefit. In a first step in the development of such an inverse dynamic multi-body simulation (MBS-) model we here present the setup of a canine hind limb model applicable for the calculation of ground reaction forces. Methods: The anatomical geometries of the MBS-model have been established using computer tomography- (CT-) and magnetic resonance imaging- (MRI-) data. The CT-data were collected from the pelvis, femora, tibiae and pads of a mixed-breed adult dog. Geometric information about 22 muscles of the pelvic extremity of 4 mixed-breed adult dogs was determined using MRI. Kinematic and kinetic data obtained by motion analysis of a clinically healthy dog during a gait cycle (1 m/s) on an instrumented treadmill were used to drive the model in the multi-body simulation. Results and Discussion: As a result the vertical ground reaction forces (z-direction) calculated by the MBS-system show a maximum deviation of 1.75%BW for the left and 4.65%BW for the right hind limb from the treadmill measurements. The calculated peak ground reaction forces in z- and y-direction were found to be comparable to the treadmill measurements, whereas the curve characteristics of the forces in y-direction were not in complete alignment. Conclusion: In conclusion, it could be demonstrated that the developed MBS-model is suitable for simulating ground reaction forces of dogs during walking. In forthcoming investigations the model will be developed further for the calculation of forces and moments acting on the hip joint during different movements, which can be of help in context with the in silico development and testing of hip prostheses.
DFG/BE 1691/95-1
DFG/NO 299/7-1
DFG/SFB/599
status-type:publishedVersion
London : Biomed Central Ltd
2009-11-23
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/467
http://www.repo.uni-hannover.de/handle/123456789/490
DOI:http://dx.doi.org/10.1186/1475-925X-8-36
ISSN:1475-925X
Biomedical Engineering Online 8 (2009)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/4912022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Numerical investigations on the strain-adaptive bone remodelling in the periprosthetic femur: Influence of the boundary conditions
Behrens, Bernd-Arno
Nolte, Ingo
Wefstaedt, Patrick
Stukenborg-Colsman, Christina
Bouguecha, Anas
hip prostheses
density
forces
stems
ddc:620
Background: There are several numerical investigations on bone remodelling after total hip arthroplasty (THA) on the basis of the finite element analysis (FEA). For such computations certain boundary conditions have to be defined. The authors chose a maximum of three static load situations, usually taken from the gait cycle because this is the most frequent dynamic activity of a patient after THA. Materials and methods: The numerical study presented here investigates whether it is useful to consider only one static load situation of the gait cycle in the FE calculation of the bone remodelling. For this purpose, 5 different loading cases were examined in order to determine their influence on the change in the physiological load distribution within the femur and on the resulting strain-adaptive bone remodelling. First, four different static loading cases at 25%, 45%, 65% and 85% of the gait cycle, respectively, and then the whole gait cycle in a loading regime were examined in order to regard all the different loadings of the cycle in the simulation. Results: The computed evolution of the apparent bone density (ABD) and the calculated mass losses in the periprosthetic femur show that the simulation results are highly dependent on the chosen boundary conditions. Conclusion: These numerical investigations prove that a static load situation is insufficient for representing the whole gait cycle. This causes severe deviations in the FE calculation of the bone remodelling. However, accompanying clinical examinations are necessary to calibrate the bone adaptation law and thus to validate the FE calculations.
DFG/CRC/599
status-type:publishedVersion
London : Biomed Central Ltd
2009-04-16
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/468
http://www.repo.uni-hannover.de/handle/123456789/491
DOI:http://dx.doi.org/10.1186/1475-925X-8-7
ISSN:1475-925X
Biomedical Engineering Online 8 (2009)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/5012022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Manufacturing conditioned roughness and wear of biomedical oxide ceramics for all-ceramic knee implants
Turger, Anke
Kohler, Jens
Denkena, Berend
Correa, Tomas A.
Becher, Christoph
Hurschler, Christof
bioceramic
implant
knee endoprostheses
ddc:620
Background: Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. Methods: A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. Results: The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. Conclusions: It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices.
DFG/CRC/599
status-type:publishedVersion
London : Biomed Central Ltd.
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/477
http://www.repo.uni-hannover.de/handle/123456789/501
DOI:http://dx.doi.org/10.1186/1475-925X-12-84
ISSN:1475-925X
Biomedical Engineering Online 12 (2013)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/5672022-12-02T18:24:34Zcom_123456789_1col_123456789_6doc-type:Reportdoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Electronic Packaging of Paper-Based Anisotropic Magnetoresistive Sensors
Blackburn, Jennifer
Meriem Akin
Paper-based sensors
Packaging technology
Papier-basierte Sensoren
Aufbau- und Verbindungstechnik
ddc:620
Sensor / papier-basierter
Verbindungstechnik
This report investigates adaptations of electronic packaging methods used to create stacks of these sensors. Four methods were developed and tested to determine the best option in terms of mechanical stability and electrical conductivity of the system. For the first method, a stack is created by way of through paper vias (TPVs), a hole that is cut in the pads of the sensors and then filled with electrically conductive adhesive through the openings on the two sensors to be joined. The second method is called mechanical caulking and connects sensors through pads which have been lined with copper tape backed with conductive adhesive. The connection is created with a small copper rivet which is flattened in place by compressive force. The third method is the stitching method which is inspired by sewing of fabric. A pattern of thin copper wire is stitched on the pad of a sensor that is lined with copper tape backed with conductive adhesive. The wire is then stitched through a second sensor that is treated similarly with copper tape and the stack receives the same pattern through the two layers as was applied to the first sensor alone. The final method is the collapsed daisy chain which is the linear connection of sensors to their neighboring sensors via copper tape backed with conductive adhesive. The row of sensors is then collapsed in an alternating orientation into a single stack.
status-type:publishedVersion
Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
2016-10-04
doc-type:Report
doc-type:Text
http://dx.doi.org/10.15488/543
http://www.repo.uni-hannover.de/handle/123456789/567
eng
CC BY 3.0 DE
http://creativecommons.org/licenses/by/3.0/de/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/5722022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610ddc:570ddc:600
A rolling-gliding wear simulator for the investigation of tribological material pairings for application in total knee arthroplasty
Richter, Berna I.
Ostermeier, Sven
Turger, Anke
Denkena, Berend
Hurschler, Christof
Knee joint
Knee joint replacement
Material wear
Motion cycle
Pin on disc
Plane geometry
Promising materials
Ring-on-disc
Rolling movement
Test results
Total knee arthroplasty
User intervention
Wear measurements
Wear rates
Wear simulators
Wear test
Cobalt
Joint prostheses
Joints (anatomy)
Materials testing
Polyethylenes
Surface roughness
Surgery
Thermoplastics
Ceramic materials
cobalt
polyethylene
article
biological model
ceramics
femur
instrumentation
knee arthroplasty
materials testing
methodology
motion
surface property
tibia
Arthroplasty, Replacement, Knee
Ceramics
Cobalt
Femur
Materials Testing
Models, Biological
Motion
Polyethylene
Surface Properties
Tibia
ddc:600
ddc:610
ddc:570
Background: Material wear testing is an important technique in the development and evaluation of materials for use in implant for total knee arthroplasty. Since a knee joint induces a complex rolling-gliding movement, standardised material wear testing devices such as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because they generate pure gliding motion only.Methods: A rolling-gliding wear simulator was thus designed, constructed and implemented, which simulates and reproduces the rolling-gliding movement and loading of the knee joint on specimens of simplified geometry. The technical concept was to run a base-plate, representing the tibia plateau, against a pivoted cylindrical counter-body, representing one femur condyle under an axial load. A rolling movement occurs as a result of the friction and pure gliding is induced by limiting the rotation of the cylindrical counter-body. The set up also enables simplified specimens handling and removal for gravimetrical wear measurements. Long-term wear tests and gravimetrical wear measurements were carried out on the well known material pairings: cobalt chrome-polyethylene, ceramic-polyethylene and ceramic-ceramic, over three million motion cycles to allow material comparisons to be made.Results: The observed differences in wear rates between cobalt-chrome on polyethylene and ceramic on polyethylene pairings were similar to the differences of published data for existing material-pairings. Test results on ceramic-ceramic pairings of different frontal-plane geometry and surface roughness displayed low wear rates and no fracture failures.Conclusions: The presented set up is able to simulate the rolling-gliding movement of the knee joint, is easy to use, and requires a minimum of user intervention or monitoring. It is suitable for long-term testing, and therefore a useful tool for the investigation of new and promising materials which are of interest for application in knee joint replacement implants.
DFG/Collaborative Research Center 599 for Biomedical Technology
status-type:publishedVersion
London : BioMed Central Ltd.
2010
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/548
http://www.repo.uni-hannover.de/handle/123456789/572
DOI:http://dx.doi.org/10.1186/1475-925X-9-24
ISSN:1475-925X
BioMedical Engineering Online 9 (2010)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6012022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Coupled coating formation simulation in thermal spray processes using CFD and FEM
Prehm, J.
Xin, L.
Möhwald, Kai
Bach, Friedrich-Wilhelm
Atmospheric plasma spraying
Coating formation
Particle spreading
Pore formation
Simulation
Thermal spraying
Volume of fluid method
ddc:600
ddc:620
This paper deals with the simulation of coating formation in Thermal Spray processes. That means that impingement and flattening of molten metal- or ceramic particles with a diameter of about 50 microns on a rough surface have to be regarded. In this work, this is accomplished use of the Volume of Fluid method. The disadvantage here is that only the pure flattening process can be considered. In order to implicate the shrinking of the particles due to cooling down after solidification, which is responsible for the occurrence of pores and thermal stresses, a Finite Element calculation is done subsequent to the CFD calculation. After the FEM calculation has finished, the newly generated, shrinked particle shape has to be re-imported into the CFD grid. © 2009-2012.
DFG/PAK193
DFG/BA 851/92-1
status-type:publishedVersion
Kuala Lumpur : The International Society for Science & Religion
2011
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/577
http://www.repo.uni-hannover.de/handle/123456789/601
ISSN:2180-1363
CFD Letters 3 (2011), Nr. 2
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6192022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610ddc:570ddc:600
Evaluation of the soft tissue biocompatibility of MgCa0.8 and surgical steel 316L in vivo: A comparative study in rabbits
Erdmann, Nina
Bondarenko, Alexandr
Hewicker-Trautwein, Marion
Angrisani, Nina
Reifenrath, Janin
Lucas, Arne
Meyer-Lindenberg, Andrea
Anti-cd3
B lymphocytes
Cell types
Cellular infiltration
Commonly used
Comparative studies
Fibrous tissue
Follow up
Geometrical conformation
Giant cells
Haematoxylin
Humoral immunity
Implant materials
In-vivo
Magnesium-calcium alloys
Observation Period
Screw head
Semi-quantitative
Soft tissue
Synoviocytes
Time-periods
Tissue necrosis
Antibodies
Calcium alloys
Chemical detection
Magnesium
Magnesium alloys
Muscle
Paraffin waxes
Paraffins
Pathology
Screws
Surgery
Biocompatibility
Oryctolagus cuniculus
Rattus
alloy
biomaterial
calcium
magnesium
steel
animal
article
biodegradable implant
bone screw
chemically induced disorder
chemistry
comparative study
drug effect
female
general surgery
inflammation
materials testing
methodology
pathology
rabbit
radiography
skeletal muscle
tibia
Absorbable Implants
Alloys
Animals
Biocompatible Materials
Bone Screws
Calcium
Female
General Surgery
Inflammation
Magnesium
Materials Testing
Muscle, Skeletal
Rabbits
Steel
Tibia
ddc:600
ddc:610
ddc:570
Background: Recent studies have shown the potential suitability of magnesium alloys as biodegradable implants. The aim of the present study was to compare the soft tissue biocompatibility of MgCa0.8 and commonly used surgical steel in vivo.Methods: A biodegradable magnesium calcium alloy (MgCa0.8) and surgical steel (S316L), as a control, were investigated. Screws of identical geometrical conformation were implanted into the tibiae of 40 rabbits for a postoperative follow up of two, four, six and eight weeks. The tibialis cranialis muscle was in direct vicinity of the screw head and thus embedded in paraffin and histologically and immunohistochemically assessed. Haematoxylin and eosin staining was performed to identify macrophages, giant cells and heterophil granulocytes as well as the extent of tissue fibrosis and necrosis. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection. Evaluation of all sections was performed by applying a semi-quantitative score.Results: Clinically, both implant materials were tolerated well. Histology revealed that a layer of fibrous tissue had formed between implant and overlying muscle in MgCa0.8 and S316L, which was demarcated by a layer of synoviocyte-like cells at its interface to the implant. In MgCa0.8 implants cavities were detected within the fibrous tissue, which were surrounded by the same kind of cell type. The thickness of the fibrous layer and the amount of tissue necrosis and cellular infiltrations gradually decreased in S316L. In contrast, a decrease could only be noted in the first weeks of implantation in MgCa0.8, whereas parameters were increasing again at the end of the observation period. B-lymphocytes were found more often in MgCa0.8 indicating humoral immunity and the presence of soluble antigens. Conversely, S316L displayed a higher quantity of T-lymphocytes.Conclusions: Moderate inflammation was detected in both implant materials and resolved to a minimum during the first weeks indicating comparable biocompatibility for MgCa0.8 and S316L. Thus, the application of MgCa0.8 as biodegradable implant material seems conceivable. Since the inflammatory parameters were re-increasing at the end of the observation period in MgCa0.8 it is important to observe the development of inflammation over a longer time period in addition to the present study.
DFG/Collaborative Research Centre/599
status-type:publishedVersion
London : BioMed Central Ltd.
2010
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/595
http://www.repo.uni-hannover.de/handle/123456789/619
DOI:http://dx.doi.org/10.1186/1475-925X-9-63
ISSN:1475-925X
BioMedical Engineering Online 9 (2010)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6292022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610ddc:570ddc:600
In vitro corrosion of ZEK100 plates in Hank's Balanced Salt Solution
Waizy, Hazibullah
Weizbauer, Andreas
Modrejewski, Christian
Witte, Frank
Windhagen, Henning
Lucas, Arne
Kieke, Marc D.K.
Denkena, Berend
Behrens, Peter
Meyer-Lindenberg, Andrea
Bach, Friedrich-Wilhelm
Thorey, Fritz
Corrosion
In vitro study
Magnesium alloy
Plates
Corrosion property
Degradation behavior
Four-point bending test
Hank's balanced salt solutions
In-vitro
Mg content
Natural bone
Orthopedic implant
Physiological condition
Plates
Resorbable materials
Stress shielding
Calcium phosphate
Corrosion
Magnesium
Magnesium alloys
Mechanical properties
Salt removal
Surfaces
Magnesium printing plates
alloy
bicarbonate
biomaterial
Hanks Balanced Salt Solution
isotonic solution
magnesium
article
chemistry
corrosion
hydrodynamics
immersion
mechanics
surface property
Alloys
Bicarbonates
Biocompatible Materials
Corrosion
Hydrodynamics
Immersion
Isotonic Solutions
Magnesium
Mechanical Processes
Surface Properties
ddc:600
ddc:610
ddc:570
Background: In recent years magnesium alloys have been intensively investigated as potential resorbable materials with appropriate mechanical and corrosion properties. Particularly in orthopedic research magnesium is interesting because of its mechanical properties close to those of natural bone, the prevention of both stress shielding and removal of the implant after surgery.Methods: ZEK100 plates were examined in this in vitro study with Hank's Balanced Salt Solution under physiological conditions with a constant laminar flow rate. After 14, 28 and 42 days of immersion the ZEK100 plates were mechanically tested via four point bending test. The surfaces of the immersed specimens were characterized by SEM, EDX and XRD.Results: The four point bending test displayed an increased bending strength after 6 weeks immersion compared to the 2 week group and 4 week group. The characterization of the surface revealed the presence of high amounts of O, P and Ca on the surface and small Mg content. This indicates the precipitation of calcium phosphates with low solubility on the surface of the ZEK100 plates.Conclusions: The results of the present in vitro study indicate that ZEK100 is a potential candidate for degradable orthopedic implants. Further investigations are needed to examine the degradation behavior.
DFG/SFB/599
DFG/SFB/599
status-type:publishedVersion
London : BioMed Central Ltd.
2012
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/605
http://www.repo.uni-hannover.de/handle/123456789/629
DOI:http://dx.doi.org/10.1186/1475-925X-11-12
ISSN:1475-925X
BioMedical Engineering Online 11 (2012)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6302022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
In vivo degradation behavior of the magnesium alloy land442 in rabbit tibiae
Ullmann, Berit
Reifenrath, Janin
Dziuba, Dina
Seitz, Jan-Marten
Bormann, Dirk
Meyer-Lindenberg, Andrea
μ-Computed tomography
Animal model
Biodegradation
Magnesium alloy
Mechanical stability
Animal model
Bending force
Degradation behaviours
Rare earth compositions
Reproducibilities
Sem examinations
Three-point bending test
Weight loss
Biocompatibility
Biodegradation
Computerized tomography
Corrosion rate
Degradation
Mechanical stability
Pitting
Magnesium alloys
ddc:600
ddc:624
In former studies the magnesium alloy LAE442 showed promising in vivo degradation behavior and biocompatibility. However, reproducibility might be enhanced by replacement of the rare earth composition metal "E" by only a single rare earth element. Therefore, it was the aim of this study to examine whether the substitution of "E" by neodymium ("Nd") had an influence on the in vivo degradation rate. LANd442 implants were inserted into rabbit tibiae and rabbits were euthanized after 4, 8, 13 and 26 weeks postoperatively. In vivo μCT was performed to evaluate the in vivo implant degradation behaviour by calculation of implant volume, density true 3-D thickness and corrosion rates. Additionally, weight loss, type of corrosion and mechanical stability were appraised by SEM/EDS-analysis and three-point bending tests. Implant volume, density and true 3-D thickness decreased over time, whereas the variance of the maximum diameters within an implant as well as the corrosion rate and weight loss increased. SEM examination revealed mainly pitting corrosion after 26 weeks. The maximum bending forces decreased over time.
DFG/CRC/599
status-type:publishedVersion
Basel : MDPI AG
2011
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/606
http://www.repo.uni-hannover.de/handle/123456789/630
DOI:http://dx.doi.org/10.3390/ma4122197
ISSN:1996-1944
Materials 4 (2011), Nr. 12
eng
CC BY-NC-SA 3.0 Unported
https://creativecommons.org/licenses/by-nc-sa/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6552022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:500
On the focused beam parameters of an electron gun with a plasma emitter
Kornilov, S.
Rempe, N.
Beniyash, Alexander
Murray, Nils
Electron guns
Luminance
Beam brightness
Beam parameter
Electron energies
Focal distances
Focused beams
Plasma emitters
Qualitative assessments
Welding test pieces
Radiation effects
ddc:500
ddc:530
Konferenzschrift
The report presents the measurement results of the focused beam brightness in the electron gun with plasma emitter. The beam brightness was approximately 1010 A·m-2·sr-1 under the beam power up to 4 kW and an electron energy of 60 keV at the focal distance of 0.5 m. Qualitative assessment of the beam parameters was performed by welding test pieces. The results describing the possibility in principle of using the guns with a plasma emitter in nonvacuum technological devices are presented.
status-type:publishedVersion
Bristol : Institute of Physics Publishing
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/631
http://www.repo.uni-hannover.de/handle/123456789/655
DOI:http://dx.doi.org/10.1088/1742-6596/552/1/012004
ISSN:1742-6588
Journal of Physics: Conference Series 552 (2014), Nr. 1
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6582022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:600
Optimal design of piezoelectric actuators for shunt damping techniques
Neubauer, Marcus
Piezoelectric energy harvesting
Piezoelectric shunt damping
Piezoelectric transducer
Vibration damping
Damping
Energy harvesting
Piezoelectric ceramics
Piezoelectric transducers
Piezoelectricity
Transducers
Damping performance
Piezoelectric elements
Piezoelectric energy harvesting
Piezoelectric shunt damping
Shunt damping techniques
Strain distributions
Vibration behavior
Vibration-damping
Piezoelectric actuators
ddc:600
ddc:530
In vibration control with piezoceramics, a high coupling of the piezoelement with the structure is desired. A high coupling improves the damping performance of passive techniques like shunt damping. The coupling can be influenced by a the material properties of the piezoceramics, but also by the placement within the structure and the size of the transducer. Detailed knowlegde about the vibration behavior of the structure is required for this. This paper presents an in-depth analysis of the optimal shape of piezoelectric elements. General results for one-dimensional, but inhomogeneos strain distribution are provided. These results are applied to the case of a longitudinal transducer and a bending bimorph. It is obtained that for maximum coupling, only a certain fracture of the volume should be made of piezoelectric material.
status-type:publishedVersion
Warsaw : Polish Academy of Sciences, Institute of Fundamental Technological Research
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/634
http://www.repo.uni-hannover.de/handle/123456789/658
DOI:http://dx.doi.org/10.2478/aoa-2014-0066
ESSN:2300-262X
Archives of Acoustics 39 (2014), Nr. 4
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6592022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610ddc:570ddc:600
Outer electrospun polycaprolactone shell induces massive foreign body reaction and impairs axonal regeneration through 3D multichannel chitosan nerve guides
Duda, Sven
Dreyer, Lutz
Behrens, Peter
Wienecke, Soenke
Chakradeo, Tanmay
Glasmacher, Birgit
Haastert-Talini, Kirsten
chitosan
polycaprolactone
biomaterial
chitosan
polycaprolactone
polyester
adult
animal experiment
article
automutilation
controlled study
electric field
electrophysiological procedures
electrospinning
extracellular space
female
foreign body reaction
freeze drying
giant cell
in vivo study
microenvironment
nerve fiber regeneration
nerve transplantation
nociception
nonhuman
peripheral nerve
rat
scanning electron microscopy
sciatic nerve
animal
chemically induced
convalescence
drug effects
electrodiagnosis
foreign body reaction
inflammation
motor activity
muscle
nerve fiber
nerve regeneration
organ size
pathology
pathophysiology
procedures
tissue regeneration
tissue scaffold
Wistar rat
Animals
Axons
Biocompatible Materials
Chitosan
Electrodiagnosis
Female
Foreign-Body Reaction
Guided Tissue Regeneration
Inflammation
Microscopy, Electron, Scanning
Motor Activity
Muscles
Nerve Regeneration
Organ Size
Pain Perception
Polyesters
Rats, Wistar
Recovery of Function
Tissue Scaffolds
ddc:600
ddc:610
ddc:570
We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10 mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts.
Internationale Stiftung Neurobionik, Germany
status-type:publishedVersion
New York, NY : Hindawi Publishing Corporation
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/635
http://www.repo.uni-hannover.de/handle/123456789/659
DOI:http://dx.doi.org/10.1155/2014/835269
ISSN:2314-6133
BioMed Research International 2014 (2014)
eng
CC BY 3.0 Unported
https://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6652022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610ddc:600
Polyethylenimine-mediated gene delivery into human bone marrow mesenchymal stem cells from patients
Wang, Weiwei
Li, Wenzhong
Ou, Lailiang
Flick, Eva
Mark, Peter
Nesselmann, Catharina
Lux, Cornelia A.
Gatzen, Hanz-Heinrich
Kaminski, Alexander
Liebold, Andreas
Lützow, Karola
Lendlein, Andreas
Li, Ren-Ke
Steinhoff, Gustav
Ma, Nan
Cardiovascular disease
Gene delivery
Human bone marrow derived mesenchymal stem cells
Non-viral vector
Polyethylenimine
DNA
green fluorescent protein
polyethyleneimine
vasculotropin A
VEGFA protein, human
adult
aged
article
bone marrow cell
cell cycle S phase
cell death
cell survival
cytology
drug effect
female
gene transfer
genetic transfection
human
male
mesenchymal stem cell
metabolism
middle aged
phenotype
Adult
Aged
Aged, 80 and over
Bone Marrow Cells
Cell Death
Cell Survival
DNA
Female
Gene Transfer Techniques
Green Fluorescent Proteins
Humans
Male
Mesenchymal Stem Cells
Middle Aged
Phenotype
Polyethyleneimine
S Phase
Transfection
Vascular Endothelial Growth Factor A
ddc:600
ddc:610
Transplantation of mesenchymal stem cells (MSCs) derived from adult bone marrow has been proposed as a potential therapeutic approach for post-infarction left ventricular (LV) dysfunction. However, age-related functional decline of stem cells has restricted their clinical benefits after transplantation into the infarcted myocardium. The limitations imposed on patient cells could be addressed by genetic modification of stem cells. This study was designed to improve our understanding of genetic modification of human bone marrow derived mesenchymal stem cells (hMSCs) by polyethylenimine (PEI, branched with Mw 25 kD), one of non-viral vectors that show promise in stem cell genetic modification, in the context of cardiac regeneration for patients. We optimized the PEI-mediated reporter gene transfection into hMSCs, evaluated whether transfection efficiency is associated with gender or age of the cell donors, analysed the influence of cell cycle on transfection and investigated the transfer of therapeutic vascular endothelial growth factor gene (VEGF). hMSCs were isolated from patients with cardiovascular disease aged from 41 to 85 years. Optimization of gene delivery to hMSCs was carried out based on the particle size of the PEI/DNA complexes, N/P ratio of complexes, DNA dosage and cell viability. The highest efficiency with the cell viability near 60% was achieved at N/P ratio 2 and 6.0 μg DNA/cm 2. The average transfection efficiency for all tested samples, middle-age group (<65 years), old-age group (>65 years), female group and male group was 4.32%, 3.85%, 4.52%, 4.14% and 4.38%, respectively. The transfection efficiency did not show any correlation either with the age or the gender of the donors. Statistically, there were two subpopulations in the donors; and transfection efficiency in each subpopulation was linearly related to the cell percentage in S phase. No significant phenotypic differences were observed between these two subpopulations. Furthermore, PEI-mediated therapeutic gene VEGF transfer could significantly enhance the expression level.
DFG/SFB/Transregio 37
BMBF/0313191
German Helmholtz Association
DFG/0402710
Ministry of Education/0312138 A
Ministry of Economy (Mecklenburg-West Pommerania)/V220-630-08-TFMVF/S-035
Marie Curie International Research Staff Exchange Scheme (IRSES, FP7-PEOPLE-2009-IRSES)
Reference and Translation Center for Cardiac Stem Cell Therapy (RTC)
status-type:publishedVersion
Chichester : Wiley-Blackwell Publishing Ltd.
2011
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/641
http://www.repo.uni-hannover.de/handle/123456789/665
DOI:http://dx.doi.org/10.1111/j.1582-4934.2010.01130.x
ISSN:1582-1838
Journal of Cellular and Molecular Medicine 15 (2011), Nr. 9
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6682022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:500
Preliminary results in anterior cervical discectomy and fusion with an experimental bioabsorbable cage - clinical and radiological findings in an ovine animal model
Daentzer, Dorothea
Floerkemeier, Thilo
Bartsch, Ivonne
Masalha, Waseem
Welke, Bastian
Hurschler, Christof
Kauth, Theresa
Kaltbeitzel, Daniel
Hopmann, Christian
Kujat, Bernd
Kalla, Katharina
ACDF
Animal model
Bioabsorbable cage
Cervical spine
Fusion
Magnesium
Ovine animal model
Poly-ε-caprolactone
Polymer
Sheep
ddc:500
Background: Bioabsorbable implants are not widely used in spine surgery. This study investigated the clinical and radiological findings after anterior cervical discectomy and fusion (ACDF) in an ovine animal model with an experimental bioabsorbable cage consisting of magnesium and polymer (poly-ε-caprolactone, PCL) in comparison to a tricortical bone graft as the gold standard procedure. Materials and Methods: 24 full-grown sheep had ACDF of C3/4 and C5/6 with an experimental bioabsorbable implant (magnesium and PCL) in one level and an autologous tricortical bone graft in the second level. The sheep were divided into 4 groups (6 sheep each). After 3, 6, 12, or 24 weeks postoperatively, the cervical spines were harvested and conventional x-rays of each operated segment were conducted. The progress of interbody fusion was classified according to a three-point scoring system. Results: There were no operation related complications except for one intraoperative fracture of the anterior superior iliac spine and two cases of screw loosening and sinking, respectively. In particular, no vascular, neurologic, wound healing or infectious problems were observed. According to the time of follow-up, both interbody fusion devices showed similar behaviour with increasing intervertebral osseointegration and complete arthrodesis in 10 of 12 (83.3%) motion segments after 24 weeks. Conclusions: The bioabsorbable magnesium-PCL cage used in this experimental animal study showed clinically no signs of incompatibility such as infectious or wound healing problems. The radiographic results regarding the osseointegration are comparable between the cage and the bone graft group.
Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF)
German Federal Ministry of Economy and Technology (BMWi)
status-type:publishedVersion
Heidelberg : SpringerOpen
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/644
http://www.repo.uni-hannover.de/handle/123456789/668
DOI:http://dx.doi.org/10.1186/2193-1801-2-418
ISSN:2193-1801
SpringerPlus 2 (2013), Nr. 1
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/6962022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:610ddc:570ddc:600
The influence of storage and heat treatment on a magnesium-based implant material: An in vitro and in vivo study
Bracht, Katja
Angrisani, Nina
Seitz, Jan-Marten
Eifler, Rainer
Weizbauer, Andreas
Reifenrath, Janin
Degradable
Aluminum
In vitro
In vivo
Magnesium
Storage
Biocompatibility
Computerized tomography
Corrosion
Corrosion resistance
Energy storage
Heat resistance
Heat treatment
Magnesium alloys
Scanning electron microscopy
Degradable
In-vitro corrosions
In-vivo experiments
Initial stabilities
Simulated body fluids
body fluid
Three point bending
Storage (materials)
alloy
lithium
unclassified drug
animal experiment
animal model
biocompatibility
biomechanics
bone mass
controlled study
corrosion
degradation
energy dispersive spectroscopy
evaluation study
ex vivo study
experimental design
grain
heat treatment
implant
in vitro study
in vivo study
micro-computed tomography
nonhuman
precipitation
priority journal
rabbit model
radiography
scanning electron microscopy
spectroscopy
three point bending
ddc:600
ddc:610
ddc:570
Background: Magnesium alloys are recommended as a potential material for osteosynthesis. It is known that storage-induced property modifications can occur in materials like aluminum. Thus the aim of this study was to analyze the influence of storage durations of up to 48weeks on the biomechanical, structural, and degradation properties of the degradable magnesium alloy LAE442. Methods: Extruded implants (n=104; Ø 2.5mm×25mm) were investigated after storage periods of 0, 12, 24, and 48weeks in three different sub-studies: (I) immediately after the respective storage duration and after an additional (II) 56days of in vitro corrosion in simulated body fluid (SFB), and (III) 48weeks in vivo corrosion in a rabbit model, respectively. In addition, the influence of a T5-heat treatment (206°C for 15h in an argon atmosphere) was tested (n=26; 0week of storage). Evaluation was performed by three-point bending, scanning electron microscopy, radiography, μ-computed tomography, evaluation of the mean grain size, and contrast analysis of precipitations (such as aluminum or lithium). Results: The heat treatment induced a significant reduction in initial stability, and enhanced the corrosion resistance. In vivo experiments showed a good biocompatibility for all implants. During the storage of up to 48weeks, no significant changes occurred in the implant properties. Conclusions: LAE442 implants can be safely used after up to 48weeks of storage.
DFG/SFB/599
status-type:publishedVersion
London : BioMed Central Ltd.
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/672
http://www.repo.uni-hannover.de/handle/123456789/696
DOI:https://doi.org/10.1186/s12938-015-0091-8
ISSN:1475-925X
BioMedical Engineering Online 14 (2015), Nr. 1
eng
CC BY 4.0 Unported
http://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7272022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:500
Non-local ductile damage formulations for sheet bulk metal forming
Beese, Steffen
Loehnert, Stefan
Wriggers, Peter
Finite element method
Forming
Locks (fasteners)
Metals
Numerical models
Sheet metal
Bulk forming process
Commercial software
Ductile damage models
Mesh-dependency
Mixed formulations
Sheet-Bulk Metal Forming
Standard elements
ddc:500
ddc:530
Konferenzschrift
A ductile damage model for sheet bulk metal forming processes and its efficient and accurate treatment in the context of the Finite Element Method is presented. The damage is introduced as a non-local field to overcome pathological mesh dependency. Since standard elements tend to show volumetric locking in the bulk forming process a mixed formulation is implemented in the commercial software simufact.forming to obtain better results.
DFG/SFB/TR 73
status-type:publishedVersion
Bristol : Institute of Physics Publishing
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/703
http://www.repo.uni-hannover.de/handle/123456789/727
DOI:http://dx.doi.org/10.1088/1742-6596/734/3/032059
ISSN:1742-6588
Journal of Physics: Conference Series 734 (2016), Nr. 3
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7372022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:500
Ex-situ and in-situ investigations of thermal anti-oxidation treatments of stainless steels by reflection mode EXAFS
Lützenkirchen-Hecht, D.
Wulff, Daniel
Wagner, R.
Holländer, Ulrich
Maier, Hans Jürgen
Frahm, R.
Atomic physics
Belt conveyors
Oxidation
Vacuum furnaces
X ray absorption
Anti-oxidation
Conveyor belts
High-vacuum environments
In-situ investigations
Inert carrier gas
Metallic state
Reflection modes
Steel surface
Ablation
ddc:500
ddc:530
Konferenzschrift
Different thermal treatments were performed for the anti-oxidation of steel surfaces, and the processes were investigated ex-situ and in-situ by surface sensitive reflection mode EXAFS experiments at the Cr and Fe K-edges. While the samples for the ex-situ studies were heat-treated in a conveyor belt furnace at temperatures between 600 and 900 °C in inert carrier gases (N2 or Ar) using different additives such as hydrogen (H2) and monosilane (SiH4), the in- situ anti-oxidation treatments have been performed in a high vacuum environment (p < 10-6 mbar). While the ex-situ experiments suggest that SiH4-additives are needed for the reduction of the steel to a metallic state, the in-vacuum treatments appear successful for temperatures above approx. 900 °C.
DFG/FR 1388/8-1
DFG/Ma 1175/48-1
status-type:publishedVersion
Bristol : Institute of Physics Publishing
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/713
http://www.repo.uni-hannover.de/handle/123456789/737
DOI:http://dx.doi.org/10.1088/1742-6596/712/1/012047
ISSN:1742-6588
Journal of Physics: Conference Series 712 (2016), Nr. 1
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7512022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
A raspberry pi based portable endoscopic 3D measurement system
Schlobohm, Jochen
Pösch, Andreas
Reithmeier, Eduard
Endoscopy
Fringe projection
Measurement
Optics
Triangulation
Endoscopy
Measurements
Optical data processing
Optics
Projection systems
Triangulation
3-D measurement systems
Contactless operation
Fringe projection
Fringe projection system
Geometry measurements
Measurement system
Optical measurement system
ddc:600
Geometry measurements are very important to monitor a machine part’s health and performance. Optical measurement system have several advantages for the acquisition of a parts geometry: measurement speed, precision, point density and contactless operation. Measuring parts inside of assembled machines is also desirable to keep maintenance cost low. The Raspberry Pi is a small and cost efficient computer that creates new opportunities for compact measurement systems. We have developed a fringe projection system which is capable of measuring in very limited space. A Raspberry Pi 2 is used to generate the projection patterns, acquire the image and reconstruct the geometry. Together with a small LED projector, the measurement system is small and easy to handle. It consists of off-the-shelf products which are nonetheless capable of measuring with an uncertainty of less than 100 μ m
DFG/SFB/871
status-type:publishedVersion
Basel : MDPI AG
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/727
http://www.repo.uni-hannover.de/handle/123456789/751
DOI:http://dx.doi.org/10.3390/electronics5030043
ISSN:2079-9292
Electronics (Switzerland) 5 (2016), Nr. 3
eng
CC BY-NC-SA 4.0 Unported
https://creativecommons.org/licenses/by-nc-sa/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7572022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersion
Development of a brazing process for the production of water- cooled bipolar plates made of chromium-coated metal foils for PEM fuel cells
Mueller, M.
Hoehlich, D.
Scharf, I.
Lampke, T.
Holländer, Ulrich
Maier, Hans Jürgen
PEM fuel cells
power source
Polymer Electrolyte Fuel Cell (PEFC)
ddc:530
Konferenzschrift
Beside lithium batteries, PEM fuel cells are the most promising strategy as a power source to achieve the targets for introducing and increasing the usage of electric vehicles. Due to limited space and weight problems, water cooled, metallic bipolar plates in a fuel cell metal stack are preferred in motor vehicles. These plates are stamped metal sheets with a complex structure, interconnected media-tight. To meet the multiple tasks and requirements in use, complex and expensive combinations of materials are currently in use (carbon fiber composites, graphite, gold-plated nickel, stainless and acid resistant steel). The production of such plates is expensive as it is connected with considerable effort or the usage of precious metals. As an alternative, metalloid nitrides (CrN, VN, W2N, etc.) show a high chemical resistance, hardness and a good conductivity. So this material category meets the basic requirements of a top layer. However, the standard methods for their production (PVD, CVD) are expensive and have a slow deposition rate and a lower layer thicknesses. Because of these limitations, a full functionality over the life cycle of a bipolar plate is not guaranteed. The contribution shows the development and quantification of an alternative production process for bipolar plates. The expectation is to get significant advantages from the combination of chromium electrodeposition and thermochemical treatment to form chromium nitrides. Both processes are well researched and suitable for series production. The thermochemical treatment of the chromium layer also enables a process-integrated brazing.
status-type:publishedVersion
Bristol : Institute of Physics Publishing
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/733
http://www.repo.uni-hannover.de/handle/123456789/757
DOI:http://dx.doi.org/10.1088/1757-899X/118/1/012005
ISSN:1757-8981
IOP Conference Series: Materials Science and Engineering 118 (2016), Nr. 1
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7672022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:620
Analysis of an experimental setup for structural damping identification
Hentschel, Olaf Peter
Bonhage, Marius
Panning-von Scheidt, Lars
Wallaschek, Jörg
Denk, Markus
Masserey, Pierre-Alain
Damping Determination
Experimental Setup
Impact Excitation
Material Damping
Vacuum Chamber
Energy dissipation
Common models
Experimental Setup
Impact excitation
Material damping
Parameterized
Reproducibilities
Structural damping
Vacuum chambers
Damping
ddc:530
ddc:620
In the present paper, an experimental setup for structural damping determination arising from energy dissipations within the material is presented. The experimental setup is developed in such a way that all unintended damping sources are eliminated. In this connection, priority is also given to the reproducibility of the experimental data. In addition, a vacuum chamber is developed to reduce the damping arising from the interaction with the surrounding medium. Furthermore, beam-shaped specimens are clamped in a suspended way, using screws with an apex to fix the specimens in their nodes of vibration. Then, the influence of test rig specific parameters on the damping value is analyzed. In this context, an ideal setup of the test rig is identified to measure structural damping values arising from dissipations within the material. Finally, a common model for material damping description is parameterized using the experimental data.
status-type:publishedVersion
Warsaw : Polish Society of Theoretical and Allied Mechanics
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/743
http://www.repo.uni-hannover.de/handle/123456789/767
DOI:http://dx.doi.org/10.15632/jtam-pl.54.1.27
ISSN:1429-2955
Journal of Theoretical and Applied Mechanics 54 (2016), Nr. 1
eng
CC BY-NC 3.0 Unported
https://creativecommons.org/licenses/by-nc/3.0/legalcode
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7712022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersion
Mechanical feasibility and decentralized control algorithms of small-scale, multi-directional transport modules
Krühn, Tobias
Sohrt, Simon
Overmeyer, Ludger
Deadlock prevention
Decentralized control
Distributed control
Intralogistics
Material handling
Multiagent systems
Warehousing
ddc:330
In this paper, we describe a conveyor matrix consisting of small-scale, multi-directional transport modules that are considerably smaller than the transported packets. If a large number of these modules are combined into a matrix, the emerging network solves transport tasks through cooperation of the modules. The control of the system is decentralized: Each module has its own control and derives its actions only from its own sensor and received messages from neighboring modules. Both the mechanical feasibility of the modules and the control algorithms are presented. We show that collision-free routes can be planned by the decentralized controlled system. Lastly, we present the necessary algorithms to detect and prevent deadlocks.
European Regional Development Fund (ERDF)
BMBF
status-type:publishedVersion
Heidelberg : Springer Verlag
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/747
http://www.repo.uni-hannover.de/handle/123456789/771
DOI:http://dx.doi.org/10.1007/s12159-016-0143-x
ISSN:1865-035X
Logistics Research 9 (2016), Nr. 1
eng
CC BY 4.0 Unported
https://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7722022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Evaluation of functionalized porous titanium implants for enhancing angiogenesis in vitro
Roland, Laura
Backhaus, Samantha
Grau, Michael
Matena, Julia
Teske, Michael
Beyerbach, Martin
Escobar, Hugo Murua
Haferkamp, Heinz
Gellrich, Nils-Claudius
Nolte, Ingo
Angiogenesis
Functionalized implants
HMGB1
PCL
Titanium
VEGF
Assays
Bioactivity
Bone
Defects
Titanium
Angiogenesis
Angiogenic factor
Functionalized
High-mobility groups
HMGB1
Porous titanium implants
Vascular endothelial growth factor
VEGF
Endothelial cells
ddc:620
ddc:624
Implant constructs supporting angiogenesis are favorable for treating critically-sized bone defects, as ingrowth of capillaries towards the center of large defects is often insufficient. Consequently, the insufficient nutritional supply of these regions leads to impaired bone healing. Implants with specially designed angiogenic supporting geometry and functionalized with proangiogenic cytokines can enhance angiogenesis. In this study, Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were used for incorporation into poly-ε-caprolactone (PCL)-coated porous titanium implants. Bioactivity of released factors and influence on angiogenesis of functionalized implants were evaluated using a migration assay and angiogenesis assays. Both implants released angiogenic factors, inducing migration of endothelial cells. Also, VEGF-functionalized PCL-coated titanium implants enhanced angiogenesis in vitro. Both factors were rapidly released in high doses from the implant coating during the first 72 h.
DFG/299/11-1
status-type:publishedVersion
Basel : MDPI AG
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/748
http://www.repo.uni-hannover.de/handle/123456789/772
DOI:http://dx.doi.org/10.3390/ma9040304
ISSN:1996-1944
Materials 9 (2016), Nr. 4
eng
CC BY-NC-SA 4.0 Unported
https://creativecommons.org/licenses/by-nc-sa/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7732022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Magnetic bead-magic bullet
Ruffert, Christine
Bioanalysis
Detection
Lab-on-a-chip
magnetic bead
microfluidics
Nanomedicine
Nanoparticle
Separation
Singleplexing
Superparamagnetism
Diagnosis
Error detection
Fluidic devices
Magnetism
Medical nanotechnology
Medical problems
Microfluidics
Nanoparticles
Separation
Superparamagnetism
Bioanalysis
Control and adjustment
Innovative method
Magnetic beads
Micro fluidic system
ddc:620
Microfluidics is assumed to be one of the leading and most promising areas of research since the early 1990s. In microfluidic systems, small spherical magnetic particles with superparamagnetic properties, called magnetic beads, play an important role in the design of innovative methods and tools, especially in bioanalysis and medical sciences. The intention of this review paper is to address main aspects from the state-of-the-art in the area of magnetic bead research, while demonstrating the broad variety of applications and the huge potential to solve fundamental biological and medical problems in the fields of diagnostics and therapy. Basic issues and demands related to the fabrication of magnetic particles and physical properties of nanosize magnets are discussed in Section 2. Of main interest are the control and adjustment of the nanoparticles’ properties and the availability of adequate approaches for particle detection via their magnetic field. Section 3 presents an overview of magnetic bead applications in nanomedicine. In Section 4, practical aspects of sample manipulation and separation employing magnetic beads are described. Finally, the benefits related to the use of magnetic bead-based microfluidic systems are summarized, illustrating ongoing questions and open tasks to be solved on the way to an approaching microfluidic age.
DFG
status-type:publishedVersion
Basel : MDPI AG
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/749
http://www.repo.uni-hannover.de/handle/123456789/773
DOI:http://dx.doi.org/10.3390/mi7020021
ISSN:2072-666X
Micromachines 7 (2016), Nr. 2
eng
CC BY-NC-SA 4.0 Unported
https://creativecommons.org/licenses/by-nc-sa/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7852022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Energy-efficient Drive Concepts in Metal-forming Production
Behrens, Bernd-Arno
Bouguecha, Anas
Krimm, Richard
Teichrib, Sergej
Nitschke, Thomas
energy efficiency
metal forming
servo press
sheet metal feeder
Feeding
Metal forming
Metals
Presses (machine tools)
Sheet metal
Electrically conductive
Electromagnetic forces
Energy efficient
Feeding rate
Feeding system
New energies
Production industries
Servo press
Energy efficiency
ddc:620
Konferenzschrift
Nowadays, efficient drive solutions for the production industry are more important than ever. In view of this, new energy-efficient drive concepts for forming presses and sheet metal feeding systems are developed at the IFUM. The novel press drive is based on a power-split design, which allows a variable ram-kinematics with reduced total costs of ownership in comparison to conventional servo presses. The new feeding concept will be able to realize the contactless feed of electrically conductive sheet metals by means of electromagnetic forces. Since only the sheet metal has to be accelerated, the energy efficiency and feeding rate can be increased significantly.
DFG/BE1691/119-1
Federal Ministry of Economics and Technology
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/761
http://www.repo.uni-hannover.de/handle/123456789/785
DOI:http://dx.doi.org/10.1016/j.procir.2016.05.039
ISSN:2212-8271
Procedia CIRP 50 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7862022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Influence of Machining Parameters on Heat Generation during Milling of Aluminum Alloys
Denkena, Berend
Brüning, J.
Niederwestberg, D.
Grabowski, R.
milling
process damping
simulation
thermal behaviour
Cutting tools
Damping
Milling (machining)
Thin walled structures
Local overheating
Machining parameters
Process damping
Process parameters
simulation
Thermal behaviours
Thin walled components
Unstable process
Aluminum alloys
ddc:620
Konferenzschrift
Thin-walled components, i.e. fuselage frames of airplanes, are prone to an unstable process behavior during milling. Therefore, tools with a chamfer between the cutting edge and the flank face are often used for such machining tasks. During milling, the chamfered area comes into contact with the just cut surface. This contact leads to process damping forces and the induced heat into the workpiece in this contact zone is increased. Furthermore, the amount of induced heat depends on the process parameters. At certain spots on the machined surface this may lead to a local overheating, which can reduce stiffness significantly. When this occurs during milling of a thin-walled component, the component is often regarded as reject. In this paper, the influence of chamfers and process parameters on the induced heat into the workpiece is investigated experimentally. In addition, a simulation which predict the temperature in the workpiece in dependence of the process parameters is presented.
Ministry of Economics, Labour and Transport of Lower Saxony/ZW3-80134969
DFG/DE 447/90-2
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/762
http://www.repo.uni-hannover.de/handle/123456789/786
DOI:http://dx.doi.org/10.1016/j.procir.2016.03.192
ISSN:2212-8271
Procedia CIRP 46 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7872022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Prediction of the Principal Stress Direction for 5-axis Ball End Milling
Böß, Volker
Grove, Thilo
Denkena, Berend
Mücke, A.
Nespor, D.
Milling
Principal Stress Direction
Residual Stress
Titanium
Forecasting
Milling (machining)
Residual stresses
Titanium
Ball end milling
Compressor blades
Damaged components
Micro topography
Principal stress
Residual stress state
Stress characteristics
Surface integrity
Ball milling
ddc:620
Konferenzschrift
While regenerating damaged components, e.g. compressor blades, the removal of excess weld material called re-contouring often determines the surface integrity including the residual stress state. A load-specific residual stress state is beneficial for lifetime. This leads to the necessity to predict the resulting residual stress state after machining. The paper describes two models, which predict the principal stress direction as a residual stress characteristic for 5-axis ball nose end milling of Ti-6Al-4 V. One model uses process force components, the other is based on the microtopography of the workpiece, which is influenced by the kinematics of the process.
DFG/Collaborative Research Centre/871
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/763
http://www.repo.uni-hannover.de/handle/123456789/787
DOI:http://dx.doi.org/10.1016/j.procir.2016.02.145
ISSN:2212-8271
Procedia CIRP 45 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7882022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Energy Efficiency in Machining of Aircraft Components
Denkena, Berend
Dittrich, Marc-André
Jacob, Stefan
Aerospace Industry
Energy Efficiency
Recycling
Titanium
Aerospace industry
Economics
Life cycle
Machining
Manufacture
Recycling
Titanium
Titanium alloys
Aircraft components
Competitive pressure
Environmental aspects
Influencing parameters
Machining Process
Manufacturing process
ddc:620
Konferenzschrift
High production costs and material removal rates characterize the manufacturing of aircraft components made of titanium. Due to competitive pressure, the manufacturing processes are highly optimized from an economical perspective, whereas environmental aspects are usually not considered. One example is the recycling of titanium chips. Because of process-induced contaminations they do not meet the quality required for recycling in high-grade titanium alloys. Thus the components need to be manufactured from primary material, which leads to a poor energy balance. This paper describes a methodology to increase the recycling rate and energy efficiency of the manufacturing process by investigating the influencing parameters on chip quality of the machining process with the aim to increase the chip quality to a recyclable degree under monetary aspects. The analysis shows that the recycling rate can be significantly increased through dry cutting, which also brings economic benefits.
German Federal Ministry for Economic Affairs and Energy (BMWi)/03ET1174A
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/764
http://www.repo.uni-hannover.de/handle/123456789/788
DOI:http://dx.doi.org/10.1016/j.procir.2016.03.155
ISSN:2212-8271
Procedia CIRP 48 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7892022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Design and Optimisation of an Electromagnetic Linear Guide for Ultra-Precision High Performance Cutting
Denkena, Berend
Dahlmann, Dominik
Krueger, R.
High performance cutting
Magnetic guide
Ultra-precision machining
Precision engineering
Machine technology
Magnet configurations
Magnetic guide
Primary and secondary processing
Process requirements
Production industries
Stiffness and damping
Ultraprecision machining
Micromachining
ddc:620
Konferenzschrift
Ultra-precision machining is rarely used in the production industry due to high costs as a consequence of disproportionally long primary and secondary processing times. In this context, the implementation of innovative machine technologies presents a suitable approach to increase productivity and reduce manufacturing costs. This paper introduces the implementation of an electromagnetic linear guide within a two-axis positioning stage for ultra-precision and micro machining. Using analytical models and FEM simulations, an optimised design for the guide's structure and magnet configuration is developed with regard to the intended application in ultra-precision high performance cutting. The new guide system provides frictionless operation for rapid and precise feed movements. Stiffness and damping of the electromagnetic guide can be adjusted to current process requirements. Fine positioning of the levitating carriage within the air gap enables an increase of the overall position accuracy.
DFG/FOR/1845
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/765
http://www.repo.uni-hannover.de/handle/123456789/789
DOI:http://dx.doi.org/10.1016/j.procir.2016.02.056
ISSN:2212-8271
Procedia CIRP 46 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7902022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
A New Tool Concept for Milling Automotive Components
Denkena, Berend
Grove, Thilo
Krödel, Alexander
end-milling
milling
steel
tool geometry
wear
Automotive industry
Cutting
Cutting tools
Geometry
Iterative methods
Steel
Thin walled structures
Wear of materials
Automotive component
Cutting performance
End milling
Flexible production process
Iterative development
Secondary processing
ddc:620
Konferenzschrift
Due to the rising number of car variants, the production systems in automobile industry are driven by a strong demand for flexible production processes. In the production of thin-walled workpieces, forming and cutting processes stand in concurrence to each other. In many applications, cutting processes facilitate higher flexibility regarding possible workpiece geometries. However, the required productivity is demanding. In this paper, a multi-sectional milling tool is developed to reach the required cutting performance by minimizing secondary processing times. Tool geometry is optimized with statistical methods to enable a target oriented tool development and reduce iterative development steps in milling tool design processes.
BMBF/02PN2187
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/766
http://www.repo.uni-hannover.de/handle/123456789/790
DOI:http://dx.doi.org/10.1016/j.procir.2016.04.055
ISSN:2212-8271
Procedia CIRP 46 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/7912022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
An Active Damping Method for Chatter Vibration in Plunge Grinding Using Electromagnetic Actuators
Ahrens, M.
Dagen, M.
Denkena, Berend
Ortmaier, Tobias
Grinding
Modelling
Monitoring
Regenerative Chatter
Actuators
Cutting tools
Grinding (machining)
Grinding wheels
Magnetic actuators
Models
Monitoring
Vibrations (mechanical)
Wheels
Active vibration controls
Chatter vibrations
Conventional grinding wheel
Cylindrical plunge grinding
ddc:620
Konferenzschrift
Using conventional grinding wheels, self-excited vibrations are one of the most limiting factors in terms of productivity and process stability in cylindrical plunge grinding. Depending on the dynamic behavior of the workpiece and machine, workpiece vibration copy on the grinding wheel's surface, caused by uneven wear. This results in increasing waviness and, therefore, increasing workpiece vibration. In this context, an active vibration control, using a self-built magnetic actuator to influence the tool wear, is presented. The limits and possibilities of this influence are examined in this paper, i. e. the generation and reduction of waves on the grinding wheel. Furthermore, the prevention of chatter vibration and its robustness against parameter variation is analyzed and presented.
DFG
status-type:publishedVersion
Amsterdam : Elsevier
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/767
http://www.repo.uni-hannover.de/handle/123456789/791
DOI:http://dx.doi.org/10.1016/j.procir.2016.03.200
ISSN:2212-8271
Procedia CIRP 46 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8032022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Single image geometry inspection using inverse endoscopic fringe projection
Matthias, Steffen
Ohrt, Christoph
Pösch, Andreas
Kästner, Markus
Reithmeier, Eduard
Endoscopy
Fiberscopy
Inverse fringe projection
Sheet bulk metal forming
ddc:600
Fringe projection is an important technology for the measurement of free form elements in several application fields. It can be applied to measure geometry elements smaller than one millimeter. In combination with deviation analysis algorithms, errors in fabrication lines can be found promptly to minimize rejections. However, some fields cannot be covered by the classical fringe projection approach. Due to shadowing, filigree form elements on narrow or internal carrier geometries cannot be captured. To overcome this limitation, a fiberscopic micro fringe projection sensor was developed [1]. The new device is capable of resolutions of less than 15 m with uncertainties of about 35 m in a workspace of 3x3x3 mm. Using standard phase measurement techniques, such as Gray-code and cos-patterns, measurement times of over a second are too long for in-situ operation. The following work will introduce an approach of applying a new single image measuring method to the fiberscopic system, based on inverse fringe projection [2]. The fiberscopic fringe projection system employs a laser light source in combination with a digital micro-mirror device (DMD) to generate fringe patterns. Fiber optical image bundles (FOIB) are used as well as gradient-index lenses to project these patterns on the specimen. This advanced optical system creates high demands on the pattern generation algorithms to generate exact inverse patterns for arbitrary CAD-modelled geometries. Approaches of optical simulations of the complex beam path and the drawbacks of the limited resolutions of the FOIBs are discussed. Early results of inverse pattern simulations using a ray tracing approach of a pinhole system model are presented.
DFG/CRC/TR 73
status-type:publishedVersion
Budapest : International Measurement Confederation (IMEKO)
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/779
http://www.repo.uni-hannover.de/handle/123456789/803
ISSN:0237-028X
Acta IMEKO 4 (2015), Nr. 2
Acta IMEKO
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8092022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:500
Reduction of Thermomechanical Stress Using Electrically Conductive Adhesives
Geipel, Torsten
Rendler, Li Carlos
Stompe, Manuel
Eitner, Ulrich
Rissing, Lutz
Electrically Conductive Adhesives
Finite Element Model
Interconnection
Photovoltaic Module
Thermomechanical Stress
Adhesives
Busbars
Elastic moduli
Electric power system interconnection
Finite element method
Photovoltaic cells
Silicon
Tensile stress
Tensile testing
Bending experiments
Cell interconnection
Electrically conductive adhesives
Interconnection
Material parameter
Photovoltaic modules
Thermo-mechanical stress
Compressive stress
ddc:500
ddc:530
Konferenzschrift
We compare the thermomechanical stresses in solar cell interconnections based on electrically conductive adhesives (ECA) with soldered joints by using bending experiments and finite element analysis (FEA). Additionally, the influence of an increasing number of busbars is studied. The FEA is validated by measuring the bending of cell strips after cooling down from a single-sided interconnection process. The material parameters are determined by tensile tests, microscopy and nanoindentation. The comparison of ECA and soldering shows that an elastomer with a Young's modulus of below 0.5 GPa is capable of reducing the thermomechanical stress effectively resulting in, approximately, a mean tensile stress in the ECA of 5 MPa, 110 MPa in the ribbon, and a maximum compressive stress in the silicon of 75 MPa. Increasing the number of busbars from three to five leads to a reduction in compressive stresses in the silicon and a slight increase of the peak tensile stress in the busbars.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/785
http://www.repo.uni-hannover.de/handle/123456789/809
DOI:10.1016/j.egypro.2015.07.049
ISSN:1876-6102
Energy Procedia 77 (2015)
Energy Procedia
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8432022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:500
Stress-induced transformation in a Ni-Mn-In alloy and the concomitant change of resistivity
Kokorin, V.V.
Konoplyuk, S.M.
Dalinger, A.
Thürer, S.
Gerstein, Gregory
Mashirov, A.
Stetskiv, Y.P.
Maier, Hans Jürgen
Electric resistance
Geometrical optics
Magnetic susceptibility
Manganese
Nickel
Stresses
Unloading
Compressive strain
Martensitic structures
Mechanical stress
Optical image
Polycrystalline specimen
Sharp increase
Stress induced martensitic transformation
Stress-induced transformation
Martensitic transformations
ddc:500
ddc:530
Konferenzschrift
In this work, the influence of mechanical stress on magnetic properties and electric resistance of a Ni-Mn- In alloy was studied. It is shown that compression of Ni-Mn-In polycrystalline specimens brings about a stressinduced martensitic transformation. Optical images recorded in-situ confirmed the formation of a martensitic structure during loading and back-transformation upon unloading. Unloading after deformation of specimens that had experienced compressive strains up to 6%resulted in full recovery of their resistivity and magnetic susceptibility. The sharp increase in the electric resistance caused by the stress-induced transformation opens up new possibilities for Ni- Mn-In alloys to be used as a material for sensors responding to mechanical stress.
status-type:publishedVersion
Les Ulis : EDP Sciences
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/819
http://www.repo.uni-hannover.de/handle/123456789/843
DOI:https://doi.org/10.1051/matecconf/20153305007
ISSN:2261236X
MATEC Web of Conferences 33 (2015)
eng
CC BY 4.0 Unported
https://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8442022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:510ddc:500
FEA-based optimisation of a clinching process with an open multiple-part die aimed at damage minimisation in CR240BH-AlSi10MnMg joints
Behrens, Bernd-Arno
Bouguecha, Anas
Vucetic, Milan
Hübner, Sven
Yilkiran, Deniz
Jin, Yilin
Peshekhodov, Ilya
Alloy steel
Cracks
Dies
Geometry
Bake hardening steels
Clinching process
Minimisation
Multiple parts
Optimisations
Tool designs
Aluminum alloys
ddc:500
ddc:510
Konferenzschrift
The paper presents results of a FEA-based tool design optimisation for a clinching process with an open multiple-part die. The studied materials are the bake-hardening steel CR240BH (1.5 mm) on the punch side and the die-cast aluminium alloy AlSi10MnMg (2.95 mm) on the die side. The objective of the optimisation was to minimise probability of cracks that appear at the outer circumference of the bottom of the clinch joint in AlSi10MnMg. In the framework of the optimisation, it was possible to minimise crack probability by varying geometrical parameters of the tools though at the cost of slightly worse but still tolerable geometrical parameters of the clinch joint.
German Federation of Industrial Research Associations (AiF), Cologne
German Federal Ministry of Economic Affairs and Energy (BMWi)
Volkswagen AG
BTM Blechverbindungstechnik GmbH
status-type:publishedVersion
Les Ulis : EDP Sciences
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/820
http://www.repo.uni-hannover.de/handle/123456789/844
DOI:https://doi.org/10.1051/matecconf/20152104009
ISSN:2261236X
MATEC Web of Conferences 21 (2015)
eng
CC BY 4.0 Unported
https://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8452022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:510ddc:500
Implementation of the Bai and Wierzbicki fracture criterion in QForm and its application for cold metal forming and deep drawing technology
Gladkov, Yury
Peshekhodov, Ilya
Vucetic, Milan
Bouguecha, Anas
Behrens, Bernd-Arno
Algorithms
Computer software
Deep drawing
Fracture
Metal drawing
Metal forming
Deep-drawing process
Fracture criteria
Fracture prediction
ITS applications
Metal-forming process
Drawing (forming)
ddc:500
ddc:510
Konferenzschrift
The paper presents implementation of fracture prediction algorithm for a cold metal forming process simulation in the software QForm. Authors programmed the function for calculation of the criterion proposed by Bai and Wierzbicki. Obtained results of the simulation in QForm for a deep drawing process are compared with results of experiments. A good agreement between the simulation and experiment was achieved.
Ministry of Education and Science of the Russian Federation
DAAD
status-type:publishedVersion
Les Ulis : EDP Sciences
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/821
http://www.repo.uni-hannover.de/handle/123456789/845
DOI:https://doi.org/10.1051/matecconf/20152112009
ISSN:2261236X
MATEC Web of Conferences 21 (2015)
eng
CC BY 4.0 Unported
https://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8462022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Simulation-based planning of production capacity through integrative roadmapping in the wind turbine industry
Denkena, Berend
Winter, F.
Decision making
Planning
Simulation
Decision making
Gears
Manufacture
Planning
Wind turbines
Interdisciplinary planning
Manufacturing technologies
Planning phase
Production capacity
Production strategy
Simulation
Software implementation
Wind turbine industry
Turbomachine blades
ddc:600
Konferenzschrift
The development and effective implementation of a production strategy requires an interdisciplinary planning of products, manufacturing technologies and factory concepts. The integrative roadmapping allows the merging of these planning areas and takes into account the occurring interactions. This article shows the concept and software implementation of the integrative roadmapping for a systematic creation of roadmaps using the example of rotor blade production in the wind turbine industry. To reduce planning time and cost the workflow in the rotor blade production has been transferred to a material flow simulation to estimate the mutual impact on the production capacity by product, technology and factory within the planning phase.
DFG/DE 447/99-1
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/822
http://www.repo.uni-hannover.de/handle/123456789/846
DOI:https://doi.org/10.1016/j.procir.2015.06.020
ISSN:22128271
Procedia CIRP 33 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8472022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersion
Holistic approach of lean thinking in learning factories
Goerke, Matthias
Schmidt, Maurice
Busch, Jan
Nyhuis, Peter
Holistic approach
Lean administration
Lean production
Learning factory
Economics
Productivity
Administrative process
Holistic approach
Institute of production systems and logistics
Integral optimization
Learning factory
Organizational structures
Production environments
Productivity improvements
Lean production
ddc:330
Konferenzschrift
Simulation games that employ the "learning by doing" approach are used to transfer complex knowledge from the most diverse fields of economy. Their popularity steadily continues to grow in the framework of seminars and workshops. The Institute of Production Systems and Logistics (IFA) applies this style of haptic learning in order to teach Lean Management contents to students as well as industry specialists and executives. During the interactive training sessions participants are involved in realistic operating situations including actual assembly processes and learn practically relevant research contents. This paper presents a training concept offered within the "IFA Lernfabrik" that incorporates the philosophy and application of Lean Thinking. Particular attention is given to the simultaneous consideration of production and administration. This synchronized approach is based on the fact that presently the administration side offers very high productivity potentials, while the vast majority of improvement activities is performed in production. To provide a better understanding for this approach, an interactive two-stage training environment was designed to highlight the advantages of Lean Production and Lean Administration methods. The first stage challenges the participants with a situation that is characterized by an inefficient production environment and limited administrative features. The aim is to improve the current situation through the utilization of the lean methods learned during the first stage training session. Within the second stage, the administrative features are being extended, which initially still exhibit wasteful characteristics. It becomes obvious that the advantages of an optimized production are not fully realized due to inefficient administrative processes. This clarifies the principle that productivity improvement activities should always entail an integral optimization of business processes. Therefore, the participants subsequently learn how to transfer and apply the methods of Lean Production in administration as tools to not only optimize their production but the entire organizational structure.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/823
http://www.repo.uni-hannover.de/handle/123456789/847
DOI:https://doi.org/10.1016/j.procir.2015.02.221
ISSN:22128271
Procedia CIRP 32 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8482022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Investigation of the skive hobbing process by applying a dexel-based cutting simulation
Böß, Volker
Denkena, Berend
Henning, S.
cutting simulation
dexel-based approach
skive hobbing
Life cycle
Machining
Analytical description
Cartesian coordinate
Cutting simulation
dexel-based approach
Hobbing
Position dependents
Process Modeling
Undeformed chip thickness
Gears
ddc:600
Konferenzschrift
In this paper, a novel approach for cutting simulation of skive hobbing is presented. Skive hobbing is a process applied for finishing of already hardened gears. The process is characterized by varying tool engagements and very small chip thicknesses. The paper describes the process-modeling and the analysis of the workpiece-tool contact. For efficient modeling, a novel dexel-based method is presented for the description of a gear segment with discretized stock allowance. Characteristic of the method is an analytical description of the target workpiece contour which allows to describe points of the surface by Cartesian coordinates on the winding off. Dexel are oriented orthogonal to the surface of the final workpiece contour. The initial lengths of the dexel describe the stock allowance. By cutting these dexel with a tool, a time- and position-dependent prediction of material removal values, e.g. width of undeformed chip or undeformed chip thickness, is possible. Selected results are presented and interpreted.
DFG/BO 3523/2-1
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/824
http://www.repo.uni-hannover.de/handle/123456789/848
DOI:https://doi.org/10.1016/j.procir.2015.08.062
ISSN:22128271
Procedia CIRP 37 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8492022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersionddc:600
Enabling an Industrial Robot for Metal Cutting Operations
Denkena, Berend
Lepper, Thomas
compensation
force measurement
machining robot
process monitoring
Aerospace industry
Compensation (personnel)
Cost effectiveness
Cutting
Force measurement
Industrial robots
Process monitoring
Robots
Cost effective
Cutting forces
Cutting operations
Machining robot
Measurement device
Positioning error
Static deflections
Tool deflection
Metal cutting
ddc:600
ddc:330
Konferenzschrift
This paper focuses on a cost-effective manufacturing of large frame parts for aerospace industries with an industrial robot. The main challenge is the low stiffness of a serial kinematic, resulting in positioning errors due to gravity and cutting forces. Therefore, an approach is presented to optimize positioning of a robot by compensation of tool deflection. A static deflection model of the robot is built up to calculate the deflection caused by forces acting on the spindle. To detect these forces a suitable measurement device is presented. This sensing spindle holder is calibrated to detect cutting forces.
Federal State of Lower Saxony
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/825
http://www.repo.uni-hannover.de/handle/123456789/849
DOI:https://doi.org/10.1016/j.procir.2015.08.100
ISSN:22128271
Procedia CIRP 35 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8502022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersion
Stock-market related price determination in consideration of time dynamic cost factors
Nemeti, Andrea
Denkena, Berend
Forecasting
Manufacturing
Pricing calculation
Stock market
Time dynamic costs
Commerce
Finance
Financial markets
Forecasting
Manufacture
Stochastic systems
Competitive factor
Forecasting methods
Prediction methods
Price determination
Stock market
Time dynamic
Tool performance
Costs
ddc:330
Konferenzschrift
Providing their customers with the most accurate pricing has become one of the key competitive factors ensuring commercial success for tool and mould manufacturers. However, time dynamic costs influence the pricing calculations significantly, indeed, they are rarely taken into consideration adequately. This paper presents an approach which allows to improve conventional tool performances by developing a novel forecasting method which combines mechanisms related to the stock market with techniques of stochastic prediction methods.
DFG/DE 447/72-3
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/826
http://www.repo.uni-hannover.de/handle/123456789/850
DOI:https://doi.org/10.1016/j.procir.2015.06.091
ISSN:22128271
Procedia CIRP 33 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8512022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:670
Approach for Increasing the Resource Efficiency for the Production Process of Titanium Structural Components
Denkena, Berend
Jacob, Stefan
Energy Efficiency
Process Chain
Process Optimization
Process-induced Contamination
Resource Efficiency
Structural Component
Aerospace industry
Chains
Cleaning
Contamination
Ecology
Economic and social effects
Energy efficiency
Energy utilization
Forging
Ingots
Melting
Metal castings
Metal melting
Milling (machining)
Optimization
Titanium
Cause-effect relationships
Ecological and economic
Mathematical descriptions
Optimization potential
Process chain
Resource efficiencies
Simulation environment
Structural component
Titanium alloys
ddc:670
Konferenzschrift
Titanium structural components for the aircraft industry are usually manufactured from ingots of primary material. The process chain for the fabrication of these components consists of the production of titanium sponge, the melting process, the forging process and the milling process. High chip removal rates from up to 95% due to the milling process and a high energy demand in producing the titanium sponge of about 85% of the overall energy consumption characterize the process chain. This obviously leads to a high optimization potential under monetary and energetic aspects. Recycling titanium chips for the ingot production could help to dramatically improve the overall production process in terms of ecological aspects. However, process-induced contaminations of the chips prevent the use of high amounts of these in the melting procedure. Macroscopic impurities like residues of cooling lubricant can be removed in a complex cleaning process. Yet, contaminations like oxidization cannot be eliminated, hence only a small amount of titanium chips is usable in the melting process to achieve the required purity of the titanium alloy. This paper describes a novel method to decrease the energy consumption in fabricating titanium products. By reducing process-induced contaminations, the amount of titanium chips usable in the melting process can be significantly increased and consequently the necessary quantity of titanium sponge reduced. The described method contains the investigation of relevant influencing factors like the impact of tool and cooling concept on chip quality or manufacturing costs. The research of cause-effect relationships identifies the trade-off between ecological and economic targets. A mathematical description of this relationship is implemented within a simulation environment to find an optimum between ecological and economic targets. The paper describes this approach with samples of the titanium alloy Ti6Al4 V.
BMWi/03ET1174A
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/827
http://www.repo.uni-hannover.de/handle/123456789/851
DOI:https://doi.org/10.1016/j.procir.2015.08.054
ISSN:22128271
Procedia CIRP 35 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8522022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
FTS-based face milling of micro structures
Köhler, Jens
Seibel, A.
Face milling
Fast tool servo
FTS
Gentelligent
Micro machining
Micro structures
Milling
Engineering research
Micromachining
Production
Quality control
Social networking (online)
World Wide Web
Conventional millings
Excitation signals
Face milling
Fast tool servo
FTS
Gentelligent
Spindle position
Variable frequencies
Milling (machining)
ddc:620
Konferenzschrift
This article presents a technical concept and machining possibilities for milling of micro structures with a fast tool servo (FTS). The tool is capable of tool tip displacements with a variable frequency up to 4000 Hz and an amplitude up to 30 μm. The control system of the actuator is linked to the angular spindle position, allowing to freely manipulate the excitation signal. Combining this tool system with a single tooth face milling head, micro structures on flat surfaces can be generated on conventional milling centers. Selected micro structures are machined and evaluated in terms of precision and surface quality.
DFG/CRC/653
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/828
http://www.repo.uni-hannover.de/handle/123456789/852
DOI:https://doi.org/10.1016/j.procir.2015.04.011
ISSN:22128271
Procedia CIRP 28 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8532022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:500
Estimation of load history by residual stress relaxation
Breidenstein, Bernd
Denkena, Berend
Mörke, Tobias
Hockauf, R.
Fatigue
Residual stress
Surface integrity
Fatigue of materials
Residual stresses
Stress relaxation
Stresses
Condition based maintenance
Load information
Residual stress state
Resource efficiencies
Service intervals
Subsurface properties
Surface integrity
Thermal and mechanical loads
Life cycle
ddc:500
Konferenzschrift
Focusing on the impact of machining on structural integrity and fatigue life of components the surface and subsurface properties are of major importance. It is well known that machining induced residual stresses have a significant influence on the fatigue life of a component. Due to thermal and mechanical loads during a product's life cycle these stresses relax, which is undesired in most cases. The presented approach utilizes relaxations due to mechanical load to estimate the load history of a component. It is intended to qualify residual stress relaxation as a load sensor and to determine the limits of this approach. Therefore, it is demonstrated, how the residual stress state induced by turning of AISI 1060 determines the critical load causing relaxation. Subsequently, the influence of load stress and the number of load cycles is used to build up a model. The presented approach accesses load information from mass production components. Until now, this information is typically limited to prototypical developments or high price parts equipped with external sensors. One application of life cycle data is condition-based maintenance. This technology allows to extend service intervals and prevent a premature replacement of undamaged components. Thus, cost and resource efficiency are augmented. It is demonstrated that based on the changes of residual stress, possible mechanical loads and number of load cycle combinations can be identified. The changes are used to estimate the experienced loads.
DFG/CRC/653
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/829
http://www.repo.uni-hannover.de/handle/123456789/853
DOI:https://doi.org/10.1016/j.procir.2015.09.006
ISSN:22128271
Procedia CIRP 37 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8542022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Influence of the cutting tool compliance on the workpiece surface shape in face milling of workpiece compounds
Denkena, Berend
Hasselberg, E.
Milling
Workpiece compound
Frequency response
Lunar surface analysis
Machining centers
Milling (machining)
Surface analysis
Surface roughness
Cutting edges
Cutting forces
Cutting properties
Frequency response analysis
Machining test
New approaches
Shape deviations
Workpiece
Cutting tools
ddc:600
Konferenzschrift
A currently common method to design high-performance workpieces is to combine two or more materials to one compound. In this way, workpieces can be composed of the most qualified materials according to local loads. When machining high-performance workpiece compounds high quality requirements concerning the accuracy of dimension and shape as well as surface roughness must be fulfilled. However, in case of parallel machining, where the cutting edge moves from one material into the other within one cutting tool revolution, unequal cutting properties have a significant negative influence on tool wear and surface quality. Shape deviations of the surface occur, which are not detected when machining the single materials. The four most significant shape deviations that affect the workpiece quality are the material height deviation, transition deviation at the material joint as well as surface roughness deviation. This paper contains new approaches on the prediction of the surface shape that is generated by a face milling process. The focus is on the transition deviation at the material joint. It arises from a force impulse that is applied on the cutting tool and creates a wavy surface on the workpiece. This shape is predicted via cutting force prediction as well as frequency response analysis of the cutting tool and workpiece in relation to different tool holders. Furthermore, deviations between calculated surface shapes and measured surface shapes subsequent to machining tests are evaluated.
DFG/DE 447/113-1
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/830
http://www.repo.uni-hannover.de/handle/123456789/854
DOI:https://doi.org/10.1016/j.procir.2015.03.074
ISSN:22128271
Procedia CIRP 31 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8552022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:670
Self-adjusting process monitoring system in series production
Denkena, Berend
Dahlmann, Dominik
Damm, J.
Intelligent
Monitoring
Process
Errors
Expert systems
Industrial research
Machine tools
Manufacture
Parameterization
Process control
Process monitoring
Processing
Quality control
Signal processing
Tuning
Correlation analysis
Monitoring system
Multi-purpose machines
Process monitoring system
Reference signals
Sensitive features
Series production
ddc:670
Konferenzschrift
Modern monitoring systems in machine tools are able to detect process errors promptly. Still, the application of monitoring systems is restricted by the complexity of parameterization for save monitoring. In most cases, only specially trained personnel can handle this job especially for multi-purpose machines. The aim of the research project "Proceed" is to figure out in which extent a self-parameterization and autonomous optimization of monitoring systems in industrial series production can be realized. Therefore, a self-adjusting and self-tuning process monitoring system for series production has been developed. This system is based on multi-criteria sensor signal evaluation and is able to assess its monitoring quality quantitatively. For this purpose, the complete process chain of parameterization has been automated. For series production it is assumed, that the first process is not defective. So, process sensitive features are identified by a correlation analysis with a reference signal. The reference signal is selected through an analysis of the process state by an expert system. To assess the monitoring quality resulting from automatic parameterization, normed specific values were used. These values describe the monitoring quality with the help of the distance between a feature and its threshold normed to signal amplitude and noise. A second indicator is the reaction of the monitoring system to a synthetic error added to signal a sequence. Thus it is possible to estimate monitoring quality corresponding to automatic parameterization. The validation is carried out by a comparison between the result of the assessment and the reaction ability of the monitoring system to real process errors from milling, drilling and turning processes.
DFG/DE 447/96–1
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/831
http://www.repo.uni-hannover.de/handle/123456789/855
DOI:https://doi.org/10.1016/j.procir.2015.06.042
ISSN:22128271
Procedia CIRP 33 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8562022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:670
Cyber-physical production systems combined with logistic models - a learning factory concept for an improved production planning and control
Seitz, Kai-Frederic
Nyhuis, Peter
Cyber-physical production system
Learning factory
Logistics
Embedded systems
Engineering education
Planning
Production control
Control and monitoring
Cyber physical systems (CPSs)
Individualized products
Logistic performance
Manufacturing engineering
Production planning and control
Production system
Personnel training
ddc:670
Konferenzschrift
Nowadays, production enterprises are faced with an array of challenges including increasing pressure regarding costs, demands for individualized products as well as the growing significance of logistic performance and costs, to name just a few. These in turn give rise to special requirements that the production planning, control and monitoring, among others, need to meet with suitable methods and techniques. Within this context, developments such as Industry 4.0 and cyber-physical production systems on the technology side, and approaches such as innovative learning factories for training employees hold great potential. This paper clarifies the advantages of cyber-physical systems in view of production planning, controlling and monitoring. Based on that, using the concept of IFA's Learning Factory, it describes how these can be specifically utilized in applying logistic models to improve order processing.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/832
http://www.repo.uni-hannover.de/handle/123456789/856
DOI:https://doi.org/10.1016/j.procir.2015.02.220
ISSN:22128271
Procedia CIRP 32 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8572022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Fluiddynamic planar drive with unrestrained rotational degree of freedom
Denkena, Berend
Dahlmann, Dominik
Schumacher, T.
Desktop machine
Bearings (machine parts)
Fluid dynamics
Gas dynamics
Life cycle
Machine components
Machine tools
Nozzle design
Precision engineering
Shafts (machine components)
Aerostatic bearings
Direct drive
Drive systems
Geometrical constraints
Pre-stressed
Rotational degree of freedom
Technical implementation
Thrust forces
Degrees of freedom (mechanics)
ddc:620
Konferenzschrift
In this paper, a new planar drive system for the use in small machine tools is introduced. It is based on an innovative fluid dynamic drive principle, which generates thrust forces by the deflection of fluid jets on flow grids integrated into the slide. In addition to the translational movements in x- and y-direction, this drive allows unlimited rotation around the z-axis in any position. Advantages are the reduced number of necessary machine components and a frictionless movement by magnetically pre-stressed, aerostatic bearing. The working principle of the drive is explained and its geometrical constraints are investigated. The arrangement of the nozzles and the design of the grid profiles are optimized. Finally, the technical implementation of the drive is presented.
DFG/SPP/1476
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/833
http://www.repo.uni-hannover.de/handle/123456789/857
DOI:https://doi.org/10.1016/j.procir.2015.08.068
ISSN:22128271
Procedia CIRP 37 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8582022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:500
Prediction of the 3D surface topography after ball end milling and its influence on aerodynamics
Denkena, Berend
Böß, Volker
Nespor, D.
Gilge, P.
Hohenstein, S.
Seume, Jörg R.
Milling
Simulation
Topography
Ball milling
Forecasting
Kinematics
Machining centers
Milling (machining)
Stochastic systems
Topography
Turbomachine blades
3-D surface topography
Ball end mill
Ball end milling
Empirical data
Machining Process
Machining simulation
Simulation
Surface prediction
Surface topography
ddc:500
Konferenzschrift
The surface topography of milled workpieces often defines their performance. One example is blades in turbine engines, where the topography defines the flow losses. This type of complex goods is often machined by ball end mills, either for manufacture or repair. The literature offers various model types to predict the surface topography in order to design a machining process without prior experiment. The most accurate models use the real kinematics of the process and blend the tool with the workpiece. But this type of surface prediction ignores the differences between the reality and the simulation due to vibrations, tool chipping etc. This paper presents a combined approach using the kinematic topography from the machining simulation and adds a stochastic topography based on empirical data. It could be shown, that the usage of the stochastic topography greatly affects the flow losses and thus cannot be ignored.
DFG/CRC/871
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/834
http://www.repo.uni-hannover.de/handle/123456789/858
DOI:https://doi.org/10.1016/j.procir.2015.03.049
ISSN:22128271
Procedia CIRP 31 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8592022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:510ddc:500
Inverse determination of constitutive equations and cutting force modelling for complex tools using oxley's predictive machining theory
Denkena, Berend
Grove, Thilo
Dittrich, Marc-André
Niederwestberg, D.
Lahres, M.
Force
Material
Simulation
Carbon
Carbon steel
Computation theory
Constitutive equations
Constitutive models
Cutting
Cutting tools
Inverse problems
Machining centers
Materials
Particle swarm optimization (PSO)
Complex tool geometry
Constitutive parameters
Material removal model
Simulation
Temperature calculation
Ultrahigh carbon steel
Undeformed chip thickness
Finite element method
ddc:500
ddc:510
Konferenzschrift
In analysis of machining processes, finite element analysis is widely used to predict forces, stress distributions, temperatures and chip formation. However, constitutive models are not always available and simulation of cutting processes with complex tool geometries can lead to extensive computation time. This article presents an approach to determine constitutive parameters of the Johnson-Cook's flow stress model by inverse modelling as well as a methodology to predict process forces and temperatures for complex three-dimensional tools using Oxley's machining theory. In the first part of this study, an analytically based computer code combined with a particle swarm optimization (PSO) algorithm is used to identify constitutive models for 70MnVS4 and an aluminium-alloyed ultra-high-carbon steel (UHC-steel) from orthogonal milling experiments. In the second part, Oxley's predictive machining theory is coupled with a multi-dexel based material removal model. Contact zone information (width of cut, undeformed chip thickness, rake angle and cutting speed) are calculated for incremental segments on the cutting edge and used as input parameters for force and temperature calculations. Subsequently, process forces are predicted for machining using the inverse determined constitutive models and compared to actual force measurements. The suggested methodology has advantages regarding the computation time compared to finite element analyses.
BMBF/02PN2050
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/835
http://www.repo.uni-hannover.de/handle/123456789/859
DOI:https://doi.org/10.1016/j.procir.2015.03.012
ISSN:22128271
Procedia CIRP 31 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8602022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Prediction of temperature induced shape deviations in dry milling
Denkena, Berend
Schmidt, A.
Maaß, P.
Niederwestberg, D.
Niebuhr, C.
Vehmeyer, J.
Deformation
Dry milling
Finite element method (FEM)
Forecasting
Heat flux
Machining centers
Milling (machining)
Geometric modelling
Material removal
Simulation
Thermal error
Finite element method
ddc:600
Konferenzschrift
In this paper a model for a simulation based prediction of temperature induced shape deviations in dry milling is presented. A closed loop between Boolean material removal, process forces, heat flux and thermoelastic deformation is established. Therefore, an efficient dexel based machining simulation is extended by a contact zone analysis to model the local workpiece load. Based on the computed contact zone the cutting forces and heat flux are calculated using a semi-empirical process model. For a detailed consideration of the loads they are discretized and localized on the dexel-represented workpiece surface. A projection of the localized workpiece loads on the boundary of the finite element domain, taking into account the Boolean material removal during the process, allows the calculation of the current temperature and deformation of the workpiece. By transforming these thermomechanical characteristics back to the dexel-model a consideration in the machining simulation is possible. An extended contact zone analysis is developed for the prediction of the localized shape deviations. Finally, the results of the simulation are compared with measured data. The comparison shows that workpiece temperatures, workpiece deformation and shape deviations in different workpiece areas are predicted accurately.
DFG/DE 447/90-2
DFG/MA 1657/21-2
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/836
http://www.repo.uni-hannover.de/handle/123456789/860
DOI:https://doi.org/10.1016/j.procir.2015.03.072
ISSN:22128271
Procedia CIRP 31 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8612022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Ultrafast Feed Drilling of Carbon Fiber-Reinforced Thermoplastics
Kakinuma, Yasuhiro
Ishida, Takuki
Koike, Ryo
Klemme, Heiner
Denkena, Berend
Aoyama, Tojiro
CFRTP
Drilling
High-performance drilling
Aerospace industry
Fiber reinforced plastics
Reinforcement
Thermoplastics
Carbon fiber reinforced
Dry condition
Feasibility studies
Feed-rates
Rotational drilling
Through-hole drilling
Ultra-fast
Reinforced plastics
ddc:600
Konferenzschrift
Carbon fiber-reinforced thermoplastics (CFRTP) are just beginning to be utilized for various applications such as aerospace, automobiles, and sporting goods in place of CFRPs, and the demand for through-hole drilling of CFRTPs is increasing. In this study, the machinability in drilling of CFRTPs under various conditions was experimentally analyzed in terms of the material properties, and a feasibility study of ultrafast feed drilling was conducted. The results showed that delamination at the outlet surface can be significantly suppressed during high rotational drilling when the feed rate is set to more than 3000 mm/min. By providing appropriate drilling conditions to prevent polymers in CFRTPs from softening, ultra-fast drilling of CFRTPs was successfully achieved under dry conditions.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/837
http://www.repo.uni-hannover.de/handle/123456789/861
DOI:https://doi.org/10.1016/j.procir.2015.08.074
ISSN:22128271
Procedia CIRP 35 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8642022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersion
Model-based feedback control of an ultrasonic transducer for ultrasonic assisted turning using a novel digital controller
Ille, I.
Twiefel, J.
Averaging Model
Feedback Control
Model-based
Resonating Systems
Cutting tools
Feedback control
Natural frequencies
Resonance
Stability criteria
Transducers
Turning
Ultrasonic transducers
Material inhomogeneity
Model based feedback controls
Model-based OPC
Phase sensitive demodulation
Resonance frequencies
Time-variant parameters
Ultrasonic assisted turnings
Controllers
ddc:530
Konferenzschrift
Ultrasonic turning has time variant parameters due to temperature effects and changing load conditions during the process. This results in a change of the resonance frequency and vibration amplitude. To realize constant vibration amplitudes it is necessary to control the ultrasonic transducer by a suitable feedback controller. One approach to drive such a system is to use the resonance frequency as operating point in connection with an amplitude feedback controller. The advantages of resonant driven low damped systems are low voltages and high values of effective power. This paper presents a digital system used for parameter identification and model-based feedback control of the ultrasonic turning tool. During the turning process the system load depends on several factors like chip formation, material inhomogeneity, warming and tool wear. To achieve a stable process and a uniform surface of the work piece the feedback controller has to guarantee constant vibration amplitudes of the ultrasonic tool. The controller used in this paper consists of a digital resonance controller and a current amplitude controller with a frequency of 500 Hz. The current amplitude and phase between the excitation voltage and current are determined by phase sensitive demodulation (PSD). To determine the feedback parameters a model-based approach is used.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/840
http://www.repo.uni-hannover.de/handle/123456789/864
DOI:https://doi.org/10.1016/j.phpro.2015.08.043
ISSN:18753884
Physics Procedia 70 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8652022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersion
Ultrasonic friction reduction in elastomer - Metal contacts and application to pneumatic actuators
Pham, T.M.
Twiefel, J.
Friction Control
Pneumatic Actuator
Rubber-Metal Contact
Ultrasonic Friction Reduction
Ultrasonic Transducer Design
Actuators
Design
Friction
Metals
Pneumatic equipment
Pneumatics
Rubber
Transducers
Tribology
Ultrasonic transducers
Friction reduction
Integrated transducers
Material combination
Metal contacts
Metal-metal contacts
Stiffness and damping characteristics
Vibration amplitude
Pneumatic actuators
ddc:530
Konferenzschrift
Ultrasonic friction reduction is well known in metal-metal contacts. Due to the vibration, the stick phase in the contact phase vanishes and only sliding occurs. As long as the macroscopic relative velocity of the contact partners is much lower than vibration velocity, the necessary force to move the parts tends to (nearly) zero. If the effect also exists in material combinations with a significant difference in stiffness and damping characteristic has not been investigated in the past. This contribution shows the effect for various material combinations, which are typical for sealings in pneumatic actuators. Further, a novel integrated transducer design for a pneumatic actuator is presented. In this design the transducer also acts as moving part within the pneumatic actuator. The design challenges are the two contact areas on the moving part, where the friction reduction and consequently high vibration amplitudes are needed. The first area is fixed on the transducer geometry, the other is moving along the piston. This novel design has been implemented in the laboratory; detailed experimental results are presented in this contribution.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/841
http://www.repo.uni-hannover.de/handle/123456789/865
DOI:https://doi.org/10.1016/j.phpro.2015.08.040
ISSN:18753884
Physics Procedia 70 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8662022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersion
Influence of the Gap Width on the Geometry of the Welded Joint in Hybrid Laser-Arc Welding
Turichin, G.
Tsibulskiy, I.
Kuznetsov, M.
Akhmetov, A.
Mildebrath, Maximilian
Hassel, Thomas
gap influence
high strength steel
Hybrid laser-arc welding
mathematical model
welded joint geometry
ddc:530
Konferenzschrift
The aim of this research was the experimental investigation of the influence of the gap width and speed of the welding wire on the changes of the geometry in the welded joint in the hybrid laser-arc welding of shipbuilding steel RS E36. The research was divided into three parts. First, in order to understand the influence of the gap width on the welded joint geometry, experimental research was done using continuous wave fiber laser IPG YLS-15000 with arc rectifier VDU-1500DC. The second part involved study of the geometry of the welded joint and hardness test results. Three macrosections from each welded joint were obtained. Influence of the gap width and welding wire speed on the welded joint geometry was researched in the three lines: in the right side of the plates, middle welded joint and in the root welded joint.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/842
http://www.repo.uni-hannover.de/handle/123456789/866
DOI:https://doi.org/10.1016/j.phpro.2015.11.013
ISSN:18753884
Physics Procedia 78 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8872022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Cyclic degradation of titanium-tantalum high-temperature shape memory alloys - The role of dislocation activity and chemical decomposition
Niendorf, T.
Krooß, P.
Somsen, C.
Rynko, R.
Paulsen, A.
Batyrshina, E.
Frenzel, J.
Eggeler, Gunther
Maier, Hans Jürgen
decomposition
Microstructure
phase transformation
training
ω-phase
Alloys
Grain boundaries
Shape memory effect
Tantalum
Titanium
Chemical decomposition
Cyclic degradations
Dislocation activity
Elevated temperature
High temperature
High temperature shape memory alloy
Structural degradation
Thermo-mechanical loading
ddc:600
Titanium-tantalum shape memory alloys (SMAs) are promising candidates for actuator applications at elevated temperatures. They may even succeed in substituting ternary nickel-titanium high temperature SMAs, which are either extremely expensive or difficult to form. However, titanium-tantalum alloys show rapid functional and structural degradation under cyclic thermo-mechanical loading. The current work reveals that degradation is not only governed by the evolution of the ω-phase. Dislocation processes and chemical decomposition of the matrix at grain boundaries also play a major role.
DFG/NI1327/3-1
DFG/MA1175/34-1
DFG/EG101/22-1
DFG/FR2675/3-1
status-type:publishedVersion
Singapore : World Scientific Publishing Co. Pte Ltd
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/863
http://www.repo.uni-hannover.de/handle/123456789/887
DOI:https://doi.org/10.1142/S1793604715500629
ISSN:17936047
Functional Materials Letters 8 (2015), Nr. 6
eng
CC BY 4.0 Unported
https://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8882022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersion
Improved Microtransformer Design Utilizing Fe-Co Magnetic Core
Dinulovic, Dragan
Gerfer, Alexander
Haug, Martin
Kaiser, Matthias
Wurz, Marc Christopher
Rissing, Lutz
Magnetic
MEMS
Microinductor
Microtransformer
Thin-film Fabrication
Physics
Current capability
Electrical resistances
High-frequency power applications
Micro inductors
Micro-transformer
Stable characteristics
Magnetism
ddc:530
Konferenzschrift
This paper presents the design, fabrication, and characterization of on silicon integrated micro-transformers for high frequency power applications. This device has stable characteristic of L versus f up to frequencies higher as 50 MHz. The design is improved, so that the electrical resistance of coils is reduced and current capability is increased. The microtransformer shows an inductivity of about 50 nH, resistance of 350 mΩ and can be applied for current up to 1.5 A.
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/864
http://www.repo.uni-hannover.de/handle/123456789/888
DOI:https://doi.org/10.1016/j.phpro.2015.12.138
ISSN:18753884
Physics Procedia 75 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8892022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Electromagnetic levitation guide for use in ultra-precision milling centres
Denkena, Berend
Dahlmann, Dominik
Krueger, R.
machine tool
ultra-precision machining
Electromagnetic propulsion
Levitation melting
Life cycle
Milling (machining)
Precision engineering
Productivity
Cutting parameters
Deterministic methods
Electromagnetic levitation
Engineering process
Magnetic guide
Precision machines
Ultra precision millings
Ultraprecision machining
Machine tools
ddc:600
ddc:620
Konferenzschrift
Today's machine tools for ultra-precision machining are generally characterised by low productivity. Above all, practical cutting parameters are limited due to uncontrollable disturbance forces. Therefore, it is necessary to pursue the qualification of new technologies to overcome current limitations in productivity. In this paper, an approach for the design of a novel electromagnetic levitation guide for use in ultra-precision milling centres is presented. Design and arrangement of the magnetic guide's components are considered with regard to requirements and design principles of precision machines. Deterministic methods are utilised throughout the engineering process to ensure high stiffness and high dynamics. As a result, a concept for the electromagnetic ultra-precision linear guide is derived.
DFG/FOR/1845
status-type:publishedVersion
Amsterdam : Elsevier
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/865
http://www.repo.uni-hannover.de/handle/123456789/889
DOI:https://doi.org/10.1016/j.procir.2015.08.008
ISSN:22128271
Procedia CIRP 37 (2015)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/8942022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:530status-type:publishedVersionddc:500
Orientation dependence of the shape memory effect and superelasticity in ferromagnetic Co49Ni21Ga30 single crystals with γ'-phase particles
Kuksgauzen, I.V.
Kireeva, I.V.
Chumlyakov, Y.I.
Maier, Hans Jürgen
Cobalt
Elasticity
Ferromagnetic materials
Ferromagnetism
Gallium
Gallium alloys
Hysteresis
Martensitic transformations
Nickel
Precipitation (chemical)
Shape memory effect
Single crystals
Orientation dependence
Phase particles
Reversible strain
Single phase
Stress hysteresis
Superelasticity
Crystal orientation
ddc:500
ddc:530
Konferenzschrift
This paper reports on the orientation dependence of the shape memory effect and superelasticity in [001] and [123] single-phase and aged at 623K, 1 hour single crystals of ferromagnetic Co49Ni21Ga30 (at.%) alloy with B2-L10 martensitic transformation. It was demonstrated that in single-phase crystals the values of reversible strain and the values of thermal and stress hysteresis depend on the crystal orientation. Precipitation of γ'-phase particles reduces the value of the shape memory effect and superelasticity and reduces their orientation dependence, increases the thermal and stress hysteresis in comparison with singlephase crystals.
Tomsk State University Academic D.I. Mendeleev Fund Program
Russian Fund for Fundamental Research
status-type:publishedVersion
London : Institute of Physics Publishing
2015
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/870
http://www.repo.uni-hannover.de/handle/123456789/894
DOI:https://doi.org/10.1088/1757-899X/93/1/012033
ISSN:17578981
IOP Conference Series: Materials Science and Engineering 93 (2015), Nr. 1
eng
CC BY 3.0 Unported
http://creativecommons.org/licenses/by/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9312022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Thin-film microtransformer for high frequency power applications
Dinulovic, Dragan
Gerfer, Alexander
Opitz, Oliver
Kaiser, Matthias
Wurz, Marc Christopher
Rissing, Lutz
ddc:620
Konferenzschrift
This paper describes a development of a microtransformer device fabricated using thin film technology. The device is designed for higher switching frequencies beyond to 50 MHz power applications. A especially by the microtransformer is a design, which allows wide flexibility of a device by choosing a different values of an inductance and of a windings ratio. The microtransformer device is integrated on silicon substrate consisting of a closed magnetic core and six coils. Both, primary and secondary device side consist three coils. Therefore, this design allows using of a device for different switching frequencies. As a magnetic material for transformer core a permalloy NiFe45/55 was chosen.
status-type:publishedVersion
Les Ulis : EDP Sciences
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/907
http://www.repo.uni-hannover.de/handle/123456789/931
DOI:https://doi.org/10.1051/epjconf/20147506006
ISSN:21016275
EPJ Web of Conferences 75 (2014)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9322022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
The influence of deep rolling on the surface integrity of AISI 1060 high carbon steel
Abrão, A.M.
Denkena, Berend
Köhler, Jens
Breidenstein, Bernd
Mörke, Tobias
Deep rolling
Integrity
Residual stress
Mechanical properties
Rolling resistance
High carbon steels
Microhardness and microstructure
Roughness parameters
Surface integrity
Tensile residual stress
Ultimate tensile stress
Carbon steel
ddc:600
ddc:620
Konferenzschrift
The aim of this work is to study the influence of selected deep rolling parameters (rolling pressure and number of passes) on the surface integrity of fully annealed AISI 1060 high carbon steel. In addition to the mechanical properties, a comprehensive investigation on surface integrity is carried out. The findings indicate that despite the increase in surface hardness and ultimate tensile stress, deep rolling can negatively affect the yield strength. The amplitude and functional roughness parameters show a considerable reduction after deep rolling, however, increasing rolling pressure and number of passes leads to poorer surface finish. Finally, the tensile residual stress generated by turning shifts to compressive values after deep rolling and the microhardness and microstructure analyses indicate that the depth of the layer affected by deep rolling depends on both the rolling pressure and number of passes.
DFG/CRC/653
CAPES Foundation, Ministry of Education of Brazil
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/908
http://www.repo.uni-hannover.de/handle/123456789/932
DOI:https://doi.org/10.1016/j.procir.2014.04.006
ISSN:22128271
Procedia CIRP 13 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9332022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Recent progress in turbine blade and compressor blisk regeneration
Aschenbruck, Jens
Adamczuk, Rafael R.
Seume, Jörg R.
Compressor blisks
Jet-engine overhaul
Turbine blade repair
Compressors
Engines
Fighter aircraft
Jet engines
Manufacture
Repair
Turbine components
Turbines
Flexible manufacturing
Functional simulations
High pressure turbine blade
Hot gas path components
Regeneration
Regeneration process
Structural mechanics
Turbine blade
Turbomachine blades
ddc:600
ddc:620
Konferenzschrift
The regeneration process of jet engines is a highly complex, expensive and time-consuming. Especially the regeneration of high pressure turbine blades and compressor blisks are at the border of what is technically feasible. These components are highly loaded and thus substantial wear occurs. The blades and blisks must be overhauled or replaced regularly. The existing repair methods for these parts are inflexible and cannot be applied in many cases, resulting in a large number of scrapped parts. Therefore a new turbine blade regeneration process is presented. The goal of the improved process is to reduce the scrap rate and cost. This process includes an early evaluation of the condition of the hot-gas path components before disassembly, new detection methods for defects on the turbine blades surfaces, and more flexible manufacturing processes. The process is supported by production process simulations and functional simulations to predict the optimal regeneration path depending on the blade condition and the business model of the customer. The paper also presents a new approach for compressor blisk regeneration. This process will be developed and validated in the next years. New challenges in structural mechanics, aerodynamics, and manufacturing must be addressed due to the complexity of blisks. As part of the ongoing research, three new blisks will be designed and subjected to the complete regeneration path, which is also supported by simulations. In order to validate the simulations, their results will be compared to experimental results of the regenerated components on a compressor test rig.
DFG/SFB/871
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/909
http://www.repo.uni-hannover.de/handle/123456789/933
DOI:https://doi.org/10.1016/j.procir.2014.07.016
ISSN:22128271
Proceedings of the 3rd International Conference in Through-life Engineering Services, 2014, 4-5 November 2013
Procedia CIRP 22 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9342022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Approaches for improving cutting processes and machine too in re-contouring
Denkena, Berend
Boess, V.
Nespor, D.
Rust, F.
Floeter, F.
Machine tool
Process simulation
Re-contouring
Aircraft engines
Fighter aircraft
Repair
Cutting tools
Advanced process
Aircraft engine blades
Experimental investigations
Geometrical accuracy
Machine tool technology
Machined surface
Re-contouring
ddc:600
ddc:620
Konferenzschrift
Re-contouring in the repair process of aircraft engine blades and vanes is a crucial task. Highest demands are made on the geometrical accuracy as well as on the machined surface of the part. Complexity rises even more due to the unique part characteristic originating from the operation and repair history. This requires well-designed processes and machine tool technologies. In this paper, approaches for coping with these challenges and improving the re-contouring process are described and discussed. This includes an advanced process simulation with its capabilities to accurately depict different material areas and predict process forces. Beyond, experimental investigations on workpiece-tooldeflection are presented. Finally, a machine tool prototype with a novel electromagnetic guiding system is introduced and the benefits of this technology in the field of repair are outlined.
DFG/CRC/871
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/910
http://www.repo.uni-hannover.de/handle/123456789/934
DOI:https://doi.org/10.1016/j.procir.2014.06.148
ISSN:22128271
Proceedings of the 3rd International Conference in Through-life Engineering Services, 2014, 4-5 November 2014
Procedia CIRP 22 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9372022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersionddc:620ddc:510
Reliable capacity planning despite uncertain disassembly, regeneration and reassembly workloads by using statistical and mathematical approaches - Validation in subsidiaries of a global MRO company with operations in Asia, Europe and North America
Eickemeyer, Steffen C.
Steinkamp, Simon
Schuster, Bernhardt
Bodenhage, Frank
Nyhuis, Peter
Bayesian networks
Capacity planning
Complex capital goods
Damage library
Data mining
Disassembly
Forecast
Maintenance
Mixed-integer linear programming
MRO
Complex networks
Data mining
Forecasting
Integer programming
Maintenance
Capital goods
Disassembly
Mixed integer linear programming
MRO
Reassembly
Regeneration
Bayesian networks
ddc:620
ddc:330
ddc:510
Konferenzschrift
The MRO industry faces substantial challenges with regard to the capacity planning of disassembly and reassembly work. This is due to the unknown workloads when regenerating complex investment goods and is caused, in particular, by the uncertain degree of disassembly and the complex challenges of reassembly. Forecasting techniques based on Bayesian networks are developed along with mathematical models which optimize capacity utilization, job order and the resulting costs. The approaches are tested and validated in conjunction with an MRO company with global operations. The results show possibilities for enhancing the planning processes and are found to be transferable on an international scale regardless of sociocultural and process differences.
DFG/CRC/871
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/913
http://www.repo.uni-hannover.de/handle/123456789/937
DOI:https://doi.org/10.1016/j.procir.2014.10.097
ISSN:22128271
Procedia CIRP 23 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9382022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Development and analysis of microstructures for the transplantation of thermally sprayed coatings
Freiburg, D.
Biermann, D.
Peuker, A.
Kersting, P.
Maier, Hans Jürgen
Möhwald, Kai
Knödler, Patrick
Otten, Maik
Coating
Microstructure
Milling
Aspect ratio
Automotive industry
Coatings
Milling (machining)
Plasma jets
Plasma spraying
Sprayed coatings
Tribology
Wear resistance
Adhesive strength
Development process
Lightweight materials
Micromilling process
Plasma-sprayed coatings
Point of interest
Thermally sprayed coatings
Tribological surfaces
ddc:600
ddc:620
Konferenzschrift
Thermally sprayed coatings and tribological surfaces are a point of interest in many industrial sectors. They are used for better wear resistance of lightweight materials or for oil retention on surfaces. Lightweight materials are often used in the automotive industry as a weight-saving solution in the production of engine blocks. For this, it is necessary to coat the cylinder liners to ensure wear resistance. In most cases, the coating is sprayed directly onto the surface. Previous research has shown that it is possible to transfer these coatings inversely onto other surfaces. This was achieved with plasma sprayed coatings which were transplanted onto pressure-casted surfaces. These transplanted surfaces exhibited better adhesive strength, smoother surfaces, and lower form deviation compared to directly coated surfaces. Additionally, it was shown that even microstructures of a surface coated by plasma spraying can be transferred to pressure-casted surfaces. This paper presents the development and micromilling of different microstructures for transferring thermally sprayed coatings onto pressure-casted surfaces. In the development process, microstructures with different shapes and aspect ratios as well as thin tribological surfaces are designed in order to evaluate the advantages and limitations of the transplantation process. In subsequent experiments, the micromilling process and a simulation of the coating transplantation are presented and analyzed.
DFG/Mo 881/9-1
DFG/Bi 498/6-1
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/914
http://www.repo.uni-hannover.de/handle/123456789/938
DOI:https://doi.org/10.1016/j.procir.2014.03.054
ISSN:22128271
Procedia CIRP 14 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9392022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Forward variance planning and modeling of multi-variant products
Gembarski, Paul Christoph
Lachmayer, Roland
Complexity management
Product configuration
Product customization
Product structure
Shape-DoFs
Specification technique
Computer aided design
Computer aided manufacturing
Degrees of freedom (mechanics)
Design
Product development
Specifications
Structural design
Complexity management
Product design
ddc:600
ddc:620
Konferenzschrift
Planning multi-variant products in the early stage of the design process is still a challenge. In the present paper, a specification technique is introduced in order to define multi-variant products using degrees of freedom of shape attributes (in the following shape-DoFs) within the product structure. Our goal is to plan variety actively at the beginning of product development and not to describe variety by change of parameter values of the product's components as introduced in variant trees. Shape-DoFs are classified in the fields of shape attributes (dimension, position, shape as well as their combinations) on the one hand and mandatory or optional components on the other hand. Set up on this taxonomy graphical symbols are introduced to be used in product modeling. As application example, a welded pipe rack based upon the assembly structure modeling the product structure in this way is visualized in the first step. The second step is to translate the shape-DoFs into design parameters and identify relationships between them. The result is a parameter plan, as well as a configuration concept. Both can be seen as basis for CAD-modeling the product as design template which is the third step. In case of our example, Autodesk Inventor (without the ETO-Environment) is used to create the CAD-data. Discussing the effects of the proposed method, it will be shown that different shape-DoFs may cause various impacts in the whole product development process. Regarding these effects, scenarios can be performed in order to identify the cost and resource optimal variation possibilities of the product. In addition, it will be shown that different kinds of modularity according to PINE (e.g. cut-to-fit-modularity) can be predefined in the product model by using shape-DoFs.
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/915
http://www.repo.uni-hannover.de/handle/123456789/939
DOI:https://doi.org/10.1016/j.procir.2014.03.161
ISSN:22128271
Procedia CIRP 21 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9402022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Prediction of process forces and stability of end mills with complex geometries
Grabowski, R.
Denkena, Berend
Köhler, Jens
Chatter
Milling
Process forces
Serrated end mills
Stability charts
Unequal helix angles
Discrete event simulation
Milling (machining)
Stability
Helix angles
Serrated end mills
Geometry
ddc:600
ddc:620
Konferenzschrift
In order to optimize the cutting performance of end mills, the geometry of such cutters is optimized by toolmakers constantly. As a result of geometric changes, process forces can be reduced, i.e. by serrated end mills. Tools with unequal helix angles can lead to an increase of process stability. In this paper, a method to calculate the process forces of end mills with complex geometries is presented. The method for calculating the process forces is designed for the application for stability analysis of end mill cutters with complex geometries. A basic introduction of the method for the stability prediction of such tools is given. Cutting forces of end mills are analyzed at incremental axial depth of cuts to show the influence of the tool geometry on the process forces. The comparison with experimental data verifies this method and shows the influence of further effects on the process forces. Furthermore, stability charts obtained with the Semi-Discretization Method are presented to show the potential of end mills with complex geometries regarding stability improvement.
Ministry for Science and Culture of Lower Saxony (MWK)
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/916
http://www.repo.uni-hannover.de/handle/123456789/940
DOI:https://doi.org/10.1016/j.procir.2014.03.101
ISSN:22128271
Procedia CIRP 14 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9412022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Residual stresses in milled β-annealed Ti6Al4V
Grove, Thilo
Köhler, Jens
Denkena, Berend
Indirect measurement method
Milling
Residual stress
Titanium
Aerospace industry
Materials science
Milling (machining)
X ray diffraction
Electrochemical materials
Grained materials
Indirect measurement method
Material removal
Residual stress state
Stress determination
Titanium alloy Ti6Al4V
Workpiece materials
Residual stresses
ddc:600
ddc:620
Konferenzschrift
Residual stresses can cause part distortion especially in the case of large components such as structural parts in aerospace industry. Therefore, this paper investigates the machining induced residual stresses for milling of a workpiece material with increasing usage in industry, the β-annealed titanium alloy Ti6Al4V. This thermal treatment results in a large grained material structure. For this reason X-ray diffraction, the standard residual stress measurement method, cannot be used for stress determination. In this paper an adopted indirect measurement method, the layer removal method is discussed. With respect to the material removal, two different methods are investigated, electrochemical material removal and laser ablation. Finally, the influence of the tool wear on the residual stress state after face milling is analyzed.
Lower Saxony Ministry for Economics, Labour and Transport
Premium Aerotec GmbH, Varel
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/917
http://www.repo.uni-hannover.de/handle/123456789/941
DOI:https://doi.org/10.1016/j.procir.2014.04.054
ISSN:22128271
Procedia CIRP 13 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9422023-02-08T10:06:45Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Automation concepts and gripping solutions for bonding with reactive multilayer systems
Heyn, J.
Blumenthal, P.
Hemken, G.
Fiedler, S.
Walz, C.
Raatz, Annika
Dröder, Klaus
Automated Assembly
Automated bonding
Gripping
Handling
Process Automation
Reactive multilayer systems
Automation
Multilayers
Multi-layer system
Process automation
Assembly
ddc:600
ddc:620
Konferenzschrift
Reactive multilayer systems (RMS) represent an innovative heat source for the establishment of solder joints. They offer fast bonding processes that introduce very little thermal input and internal stress on the bonded parts. The current application process of RMS is predominantly manual labor. There are a couple of challenges to be overcome to automate this process, a requirement for its introduction into industrial production. In this paper we evaluate the requirements for an automated joining process with RMS and devise a concept of a modular assembly system for different product structures. Furthermore we show our results in gently and reliably gripping and handling of RMS.
Federal Ministry of Economic and Technology (BMWi)
InnoJoin GmbH & Co. KG, Bremen
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/918
http://www.repo.uni-hannover.de/handle/123456789/942
DOI:https://doi.org/10.1016/j.procir.2014.03.198
ISSN:22128271
Procedia CIRP 23 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9432022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Form-flexible handling and joining technology (formhand) for the forming and assembly of limp materials
Löchte, Christian
Kunz, Holger
Schnurr, Raphael
Langhorst, Sören
Dietrich, Franz
Raatz, Annika
Dilger, Klaus
Dröder, Klaus
Assembly
Automation
Form-Flexible Handling and Joining
Handling of Objects with Different Characteristics
Preforming
Process Design
End effectors
Joining
Machine tools
Automated process
Granular fillers
Handling of Objects with Different Characteristics
Handling tools
Joining technology
Material behavior
On-line sensor
Working state
Materials handling
ddc:600
ddc:620
Konferenzschrift
The assembly of limp, elastic or differently shaped objects poses a huge challenge which needs to be met by machine tools and the corresponding processes of handling, forming and joining. These processes are often carried out manually. This technological gap triggered the present work at the Technische Universität Braunschweig. A novel form-flexible handling tool (FormHand) is presented which focuses on the automation of these production steps taking into consideration the material behavior. The combination of the flexibility of both industrial robot and the FormHand end-effector allows for new processes appropriate for these materials. This article investigates the used materials of the granular filler and the cushion textile, the working states of FormHand and the use of online sensors for an automated process application.
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/919
http://www.repo.uni-hannover.de/handle/123456789/943
DOI:https://doi.org/10.1016/j.procir.2014.10.086
ISSN:22128271
Procedia CIRP 23 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9442022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersionddc:620ddc:600
Multiscale optical inspection systems for the regeneration of complex capital goods
Schlobohm, Jochen
Li, Yinan
Pösch, Andreas
Langmann, Benjamin
Kästner, Markus
Reithmeier, Eduard
Borescope
Fringe projection
Inline measurement
Metrology
Michelson interferometer
Mulstiscale
White light interferometer
Computer generated holography
Geometry
Inspection
Inspection equipment
Interferometers
Interferometry
Measurements
Michelson interferometers
Optical data processing
Optical testing
Borescope
Mulstiscale
White-light interferometer
Projection systems
ddc:600
ddc:620
ddc:330
Konferenzschrift
The inspection of capital goods with complex geometries is a challenging task due to the limited maneuvering and measuring space available. We developed a set of optical measurement systems for the inline inspection of such machines and capital goods. At first we introduce a borescopic fringe projection system based on of-the-shelf components. It is capable of detecting geometric variances in hard to reach areas, e.g. inside machines or in between parts with highly complex geometries like blade integrated discs (blisks). Single parts like compressor blades are measured with an inverse fringe projection system, which uses fully adaptable fringe patterns. The adaptable patterns lead to a high sensitivity and high speed. Results can be achieved with only one fringe pattern per measurement. In order to perform microscopic measurements and surface characterizations, we use a michelson interferometer with advanced 3D reconstruction algorithms to detect microscopic variances of the objects surface. These newly developed algorithms lead to higher sensitivity and improved results. Together these three inspection systems enable us to detect and to quantify geometric defects or variances of different industrial parts. Based on this information the prediction of the reliability of a part can be improved and the lifetime of an industrial part can be extended leading to a reduction of maintenance costs.
DFG/SFB/871
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/920
http://www.repo.uni-hannover.de/handle/123456789/944
DOI:https://doi.org/10.1016/j.procir.2014.07.019
ISSN:22128271
Proceedings of the 3rd International Conference in Through-life Engineering Services, 4-5 November 2013
Procedia CIRP 22 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9452023-02-08T10:06:01Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:670ddc:600
Battery system development - Assembly planning between lightweight design and high volume production
Tornow, Alexander
Raatz, Annika
Dröder, Klaus
Assembly planning
Battery System
Design for Assembly
Computer aided design
Design
Electric batteries
Secondary batteries
Automated generation
Geometrical complexity
High-volume production
Passenger vehicles
Peripheral components
Assembly
ddc:600
ddc:620
ddc:670
Konferenzschrift
Battery systems of electric vehicles suffer from low energy densities as well as high masses and geometrical complexity. The absence of standards for battery cells and peripheral components in combination with large and distributed design spaces within passenger vehicles open up innumerable possibilities to design battery systems. The results are product specific and uneconomical assembly systems. This paper describes the work of the TU Braunschweig to create a methodology that generates and evaluates modular and easy to assemble battery systems based upon user requirements. This methodology gathers and links requirements between the priorities "lightweight design" and "high volume production" including a partly automated generation of CAD data. The generated concepts are directly used for assembly planning. The presented methodology therefore represents a simultaneous engineering approach that shortens development time and supports design engineers as well as process planners.
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/921
http://www.repo.uni-hannover.de/handle/123456789/945
DOI:https://doi.org/10.1016/j.procir.2014.10.101
ISSN:22128271
Procedia CIRP 23 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9462022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Disassembly of electric vehicle batteries using the example of the Audi Q5 hybrid system
Wegener, Kathirn
Andrew, Stefan
Raatz, Annika
Dröder, Klaus
Herrmann, Christoph
Disassembly
Planning approach
Recycling
Traction batteries
Electric batteries
Electric traction
Electric vehicles
Hybrid systems
Hybrid vehicles
Lithium
Planning
Secondary batteries
Vehicles
Battery recycling
Disassembly sequence
Disassembly systems
Electric vehicle batteries
Li-ion batteries
Traction battery
Work station
Lithium batteries
ddc:600
ddc:620
Konferenzschrift
The rising number of electric vehicles comes along with an increasing demand for Li-Ion batteries. As resources such as lithium are valuable it is economically worthwhile to recycle EV batteries. One of the first steps of every battery recycling process is the disassembly, which can be a quite time and cost consuming process and hence has to be planned properly. Using the battery of the hybrid car Audi Q5 as a case study, a planning approach for the disassembly will be discussed in this paper. Therefore, disassembly sequences will be derived from a priority matrix and a disassembly graph will be drawn up. Finally, recommendations for the design of the disassembly system and work stations will be given.
Audi AG and Electrocycling GmbH
Automotive Research Center Niedersachsen (NFF)
German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/922
http://www.repo.uni-hannover.de/handle/123456789/946
DOI:https://doi.org/10.1016/j.procir.2014.10.098
ISSN:22128271
Procedia CIRP 23 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9472022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Hot stamping of load adjusted structural parts
Behrens, Bernd-Arno
Bouguecha, Anas
Gaebel, Christoph Michael
Moritz, Jörn
Schrödter, Jens
Hot stamping
Masked austenitization
Press hardening
Spray cooling
Tailored properties
Accidents
Automobile manufacture
Cooling
Forging machines
Hardening
High strength steel
Manufacture
Plasticity
Presses (machine tools)
Stress analysis
Austenitization
Tailored properties
Stamping
ddc:600
ddc:620
Konferenzschrift
The importance of high-strength steel concepts for car bodies has increased in recent years due to the necessity of weight reduction and improved crash safety. By using hot stamping or also known as press hardening of boron alloyed heat-treatable steels, it is possible to produce parts with a much higher strength than by cold forming processes. Depending on the stress profile of a structural part, it might be desirable to have different material rigidity in the part, with some high strength and other more ductile areas, so called "Tailored properties". There are a variety of methods to produce such parts, but all of these methods have currently still major challenges. Two methods to manufacture parts with tailored properties, these challenges and corresponding approaches are presented in this paper. This is on the one hand subsequently cooling in a spray field, which currently is still in the development phase because of challenges related to distortion. And on the other hand, the masked austenitization, which is used by only a few manufacturers due to the lack of experience, the impairments of coating condition and the great demands on the process management concerning re-cooling of the mask. Both variants are forward-looking and deliver high potential for further research.
DFG/1691/11-2
DFG/CRC/489
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/923
http://www.repo.uni-hannover.de/handle/123456789/947
DOI:https://doi.org/10.1016/j.proeng.2014.10.227
ISSN:18777058
Procedia Engineering 81 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9482022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Numerical and experimental determination of cut-edge after blanking of thin steel sheet of DP1000 within use of stress based damage model
Behrens, Bernd-Arno
Bouguecha, Anas
Vucetic, Milan
Krimm, Richard
Hasselbusch, Tobias
Bonk, Christian
Blanking
Damage
Dual phase steel
FE-simulation
Stack-compression test
Tensile test
Compression testing
Finite element method
Fracture
Fracture mechanics
Plasticity
Tensile testing
Dual-phase steel
Elevated temperature
Experimental determination
Experimental investigations
Stress-based damage
Steel sheet
ddc:600
ddc:620
Konferenzschrift
The proposed study focuses on blanking of thin steel sheets of Dogal1000DP +Z100MBO. Numerical and experimental investigations of the influence of clearance and punch speed on the cutting force and the geometry of the sheared edge were done. Tensile and stack compression test at elevated temperatures has been chosen to determine the flow and fracture behavior of Dogal1000DP +Z100MBO at different stress states. It is shown that the flow curve determined by stack compression test leads to better results in force - displacement prediction of a blanking process compared to determination of flow curve by tensile test. Stress based fracture criterion were chosen to describe damage behaviour. Moreover significant influence of fracture locus for negative stress triaxialities on the geometry of the numerically predicted sheared edge is shown.
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/924
http://www.repo.uni-hannover.de/handle/123456789/948
DOI:https://doi.org/10.1016/j.proeng.2014.10.200
ISSN:18777058
Procedia Engineering 81 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9492022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Forming sheets of metal and fibre-reinforced plastics to hybrid parts in one deep drawing process
Behrens, Bernd-Arno
Hübner, Sven
Neumann, André
Deep drawing
Hybrid parts
Sheet metal forming
Drawing (forming)
Elastomers
Materials properties
Metal drawing
Metal forming
Metals
Plasticity
Reinforced plastics
Reinforcement
Sheet metal
Chemical and physical properties
Deep-drawing process
Fabrication Technologies
Fibre reinforced plastic (FRP)
Labour-intensive
Metal components
Metallic material
Fiber reinforced plastics
ddc:600
ddc:620
Konferenzschrift
Each material has its own advantages and disadvantages in terms of its mechanical, chemical and physical properties. Metallic materials are comparatively ductile and easy to process. Fibre reinforced plastics are very stiff and endure high tensile stresses based on their weight. By intelligent combination of these materials into one overall-part light but strong components may be established. However, the conventional production of a separate fibre reinforced plastic (FRP)-component and a metal component and a subsequent joining is time- And labour-intensive and therefore not economical in mass-production. Thus in this paper a new fabrication technology is presented.
German Federation of Industrial Research Associations (AiF)
European Research Association for Sheet Metal Working (EFB)
Federal Ministry of Economics and Technology (BMWi)
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/925
http://www.repo.uni-hannover.de/handle/123456789/949
DOI:https://doi.org/10.1016/j.proeng.2014.10.198
ISSN:18777058
Procedia Engineering 81 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9502022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Properties and application of high-manganese TWIP-steels in sheet metal forming
Busch, Christian
Hatscher, Ansgar
Otto, Manuel
Huinink, Stefan
Vucetic, Milan
Bonk, Christian
Bouguecha, Anas
Behrens, Bernd-Arno
FEM-simulation
Formability
Sheet metal forming
Twip-steel
Deep drawing
Drawing (forming)
Finite element method
Formability
Manganese
Metal drawing
Metal forming
Sheet metal
Steel
Tensile testing
Dual-phase steel
FEM simulations
Forming limit diagrams
Forming limits
Multiaxial stress
Stretch formability
Uniaxial tensile test
Plasticity
ddc:600
ddc:620
Konferenzschrift
Within this work uniaxial tensile tests have been performed with high-manganese TWIP-steel and different dual-phase steels to determine mechanical properties. The transfer of the results form uniaxial tensile tests to multi-axial stresses has been made with deep drawing experiments to describe and assess deep and stretch formability of the analysed materials. Forming limits of materials are demonstrated by forming limit diagrams. FE-simulation systems have been applied to predict deep drawing and spring-back behaviour of high-manganese TWIP in comparison to dual-phase steels. The simulation results are discussed between the different materials.
Salzgitter Mannesmann Forschung GmbH
Volkswagen Research and Development
Sitech Sitztechnik GmbH
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/926
http://www.repo.uni-hannover.de/handle/123456789/950
DOI:https://doi.org/10.1016/j.proeng.2014.10.121
ISSN:18777058
Procedia Engineering 81 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/9512022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Sandwich rolling of twin-roll cast aluminium-steel clad strips
Stolbchenko, Mykhailo
Grydin, Olexandr
Nürnberger, Florian
Samsonenko, Andrii
Schaper, Mirko
Aluminium-steel clad strips
Mechanical properties
Twin-roll casting
Aluminum
Cold rolling
Hot rolling
Metal cladding
Microstructure
Plasticity
Electron probe
Interface layer
Pure aluminium
Rolled strips
Sandwich rollings
Strain values
Twin roll cast
Twin roll casting
Steel castings
ddc:600
ddc:620
Konferenzschrift
In the present study experimental results of twin-roll cast aluminium-steel clad strips of a thickness of 2.0 mm using the example of pure aluminium and an austenitic steel are presented. Electron probe measurements of the bonding area revealed the presence of a continuous interface layer of about 2 μm. To verify the formability of the twin-roll cast clad strips, sandwich samples were cold rolled with up to 66% strain. Furthermore, the sandwich samples were hot rolled at the temperature of 300 °C with different strain values. Mechanical properties, the microstructure and the surface quality of the deformed compound after rolling were analysed. To test ductility and formability of the rolled strips these were cold deep drawn.
DFG/SCHA1484/21-1
status-type:publishedVersion
Amsterdam : Elsevier
2014
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/927
http://www.repo.uni-hannover.de/handle/123456789/951
DOI:https://doi.org/10.1016/j.proeng.2014.10.187
ISSN:18777058
Procedia Engineering 81 (2014)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10082022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
High permeability flexible bulk material for magnetic micro head applications
Belski, Alexander
Taptimthong, Piriya
Wurz, Marc Christopher
Rissing, Lutz
ddc:620
Konferenzschrift
A magnetic field is generated by feeding electric current to micro coils. The higher the current, the higher the magnetic field is. A main disadvantage of coils in micro systems is the limited thermal resistance and as a result of a restriction concerning the maximum current densities. This work shows the modelling, design, numerical calculation and the initial test of a flexible write head, which not only allows the data storage on the surface but also inside of the components. Furthermore, the write head has to be flexible and able to adapt itself to the roughness of the component surface. The main goal of this paper is to increase the magnetic flux in the micro head core by partly using high permeability flexible bulk material instead of increasing the coil current or the number of the coil turns. For the approval of the data storage process a GMR sensor is used for the readout of the stored magnetization track.
DFG/SFB/653
status-type:publishedVersion
Les Ulis : EDP Sciences
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/984
http://www.repo.uni-hannover.de/handle/123456789/1008
DOI:https://doi.org/10.1051/epjconf/20134016003
ISSN:21016275
EPJ Web of Conferences 40 (2013)
eng
CC BY 2.0 Unported
https://creativecommons.org/licenses/by/2.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10092022-12-02T15:04:50Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Early assessment of defects and damage in jet engines
Adamczuk, Rafael R.
Seume, Jörg R.
BOS
CFD
Hot gas path
Jet engine
Maintenance
Artificial defects
Background oriented schlieren methods
Density distributions
Engine maintenance
Hot-gas path
Turbine blade tip clearances
Two-stage axial turbines
Computational fluid dynamics
Damage detection
Defect density
Jet engines
Turbines
Defects
ddc:600
ddc:620
Konferenzschrift
The jet engine maintenance process is complex, expensive and time-consuming. It often requires engine disassembly or boroscopic examinations. In order to accelerate the process and reduce the down time of an engine we intend to develop a method to locate and characterize defects and damage at an early state, without having to disassemble the engine. The assumption is that various defects in the hot gas path of an engine have a noticeable impact on the spatial density distribution of the exhaust jet of an engine. The resulting differences in the exhaust jet pattern will be measured with the Background Oriented Schlieren method (BOS). We perform numerical simulations (CFD) in order to analyze the effects of various general defect types on the density pattern of the exhaust jet. The defects under investigation include the malfunction of one burner, the increase the turbine blade tip clearance and burned trailing edges of the blades. The changes in the pattern resulting from the defects are compared to the density distribution of the undamaged initial state. It is shown that different exhaust jet patterns can be linked to the investigated hot gas path defects. Furthermore, a BOS set-up is installed in a test cell of a helicopter engine with a twostage axial turbine to demonstrate the applicability of the BOS method for the measurement of small density gradients resulting from temperature non-uniformities. A cold streak was inserted into the exhaust diffuser to simulate an artificial defect. The completed measurements show that the BOS method is able to detect these small variations. The present paper summarizes the results of different investigations. It presents a combination of BOS measurements of the exhaust jet and CFD simulations of defects within the hot gas path as a promising approach for evaluating the condition of a jet engine.
DFG/CRC/871
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/985
http://www.repo.uni-hannover.de/handle/123456789/1009
DOI:https://doi.org/10.1016/j.procir.2013.07.022
ISSN:22128271
Procedia CIRP 11 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10102022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Abrasion monitoring and automatic chatter detection in cylindrical plunge grinding
Ahrens, M.
Fischer, R.
Dagen, M.
Denkena, Berend
Ortmaier, Tobias
Grinding
Modelling
Monitoring
Regenerative chatter
Acceleration sensors
Chatter vibrations
Conventional grinding wheel
Cylindrical plunge grinding
Detection and estimation
External cylindrical grinding
Regenerative chatters
Wavelet transformations
Abrasion
Eddy current testing
Grinding (machining)
Grinding machines
Grinding wheels
Machining centers
Models
Sensors
Vibrations (mechanical)
ddc:600
ddc:620
Konferenzschrift
Using conventional grinding wheels, wheel-sided chatter vibration is one of the limiting factors in terms of productivity and surface finish. Initial vibration related to the dynamic behavior of the machine tool copy on the grinding wheel and its amplitude amplifies by abrasion. To ensure high workpiece quality many expensive truing cycles are needed. In this context, we suggest a new set-up for the automatic chatter detection and elimination for external cylindrical grinding machines, reducing not only the high amount of true running cycles, but also improving the efficiency. In order to suppress the generation of the waviness on the grinding wheel the effect has to be identified during an early stage of its development. Therefore, a grinding machine is equipped with different types of sensors, i.e., eddy current, force, acoustic emission, acceleration sensors, and a tactile probe. Experimental results show, that exclusively measuring the displacement at the workpiece is sufficient for online computing wheel's waviness. Based on a model of the grinding process the other redundant sensors are used for validation. In addition, a robust online chatter detector based on the wavelet transformation is developed recognizing an instable grinding process. This model-based detection and estimation of waviness delivers solid results, it should be used for suppression of chatter in further work.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/986
http://www.repo.uni-hannover.de/handle/123456789/1010
DOI:https://doi.org/10.1016/j.procir.2013.06.119
ISSN:22128271
Procedia CIRP 8 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10112022-12-02T15:06:09Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Active tailstock for precise alignment of precision forged crankshafts during grinding
Denkena, Berend
Gümmer, Olaf
Adaptive control
Grinding
Machine
Adaptive Control
Collaborative research
Degree of freedom (dof)
Iterative learning control
Optical measurement systems
Positioning accuracy
Positioning system
Workpiece alignment
Alignment
Chains
Digital storage
Grinding (machining)
Hydraulic machinery
Industrial engineering
Machining
Navigation systems
Optical data processing
Optical variables measurement
Crankshafts
ddc:600
ddc:620
Konferenzschrift
Within the Collaborative Research Centre 489 at the Leibniz Universitaet Hannover a new and innovative process chain for the manufacture of crankshafts is being investigated. By burr-free and near-net-shaped precision forging the process chain can be significantly shortened. However, this new production process requires a precise workpiece alignment before the grinding process due to the characteristics of the new process chain. In this paper a new machine-integrated positioning system consisting of an optical measurement system (sensor) and an active tailstock (actuator) is presented. For the detection of positioning errors, the geometric elements of the crankshaft are measured by the machine integrated optical measurement system. An algorithm evaluates the geometry data and calculates an adjustment vector. This vector contains the correction of the eccentric and tilt error. The degree of freedom (DOF) of the pendulum stroke of the grinding machine will be used to correct the eccentric error. The tilt error of the crankshaft is corrected by a new active tailstock. This tailstock produces a counter-tilt during the grinding process. For this purpose, a dynamic drive of the tailstock center in two DOF as a function of the angular position has been realized by two new developed piezo-hydraulic linear drives (stroke 4 mm). The dynamics and positioning accuracy of the active tailstock were verified. Up to 10 Hz a positioning accuracy in the range of ±1.5 μm can be achieved by using an iterative learning control. Furthermore, active alignment tests during grinding were performed.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/987
http://www.repo.uni-hannover.de/handle/123456789/1011
DOI:https://doi.org/10.1016/j.procir.2013.09.022
ISSN:22128271
Procedia CIRP 12 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10122022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600ddc:500
Simulation based parameterization for process monitoring of machining operations
Denkena, Berend
Koeller, M.
Material remova
Monitoring
Simulation
Batch production
Machining operations
Process simulations
Reference parameters
Simulation
Simulation based approaches
Virtual machine tools
Computer simulation
Industrial applications
Industrial engineering
Machine tools
Monitoring
Process control
Process monitoring
ddc:600
ddc:620
ddc:500
Konferenzschrift
Process monitoring can prevent machine and tool failure in metal-cutting. A successful process monitoring of cutting processes depends on reliable monitoring limits for the process. In industrial applications these limits have to be generated in a learning phase during a ramp-up process. In order to enable process monitoring for single batch production without a learning phase, this paper describes a simulation based approach for generating reference data to set process limits. As a foundation for calculation of monitoring limits a position-based process simulation has to be established. In a first step an approach of modeling material removal is evaluated to check whether it fits the application for parameterizing the process monitoring. In this context the potentials of a process simulation for calculating process limits are clarified. Additionally the quality of data generated by this kind of simulation is discussed. In a second step a method is described to implement machine properties by a virtual machine tool within a simulation of material removal. For that purpose a method to use actual data of axis position and tool within the simulation of material removal is necessary. With these data a way-based simulation of material removal can generate reference parameters for monitoring limits instead of using data from a learning phase during the ramp-up process. By using position data of a virtual machine tool a reliable source for the actual position of all axes enables the position-based simulation to perform material removal in a more accurate way.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/988
http://www.repo.uni-hannover.de/handle/123456789/1012
DOI:https://doi.org/10.1016/j.procir.2013.09.015
ISSN:22128271
Procedia CIRP 12 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10132022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Influence of stress on the degradation behavior of Mg LAE442 implant systems
Denkena, Berend
Köhler, Jens
Stieghorst, J.
Turger, Anke
Seitz, J.
Fau, D.R.
Wolters, L.
Angrisani, Nina
Reifenrath, Janin
Helmecke, Patrick
Bioresorbable osteosynthesis magnesium LAE442 corrosion
Compressive loads
Corrosion behavior
Cylindrical specimens
Degradation behavior
Microscopic image
New Zealand White rabbit
Osteosynthesis
Rectangular samples
Corrosive effects
Magnesium
Magnesium alloys
Screws
Tensile stress
Corrosion rate
ddc:600
ddc:620
Konferenzschrift
In this paper the performance of a magnesium based implant system is analyzed. A special emphasis is placed on the impact of stress on the corrosion behavior of the magnesium alloy. An implant system containing a plate and 4 corresponding screws is machined from Mg LAE442. Its corrosion behavior is tested in-vivo in New Zealand White Rabbits for 6 and 12 weeks of implantation. The plate is monocortically fixated on the medial tibia. At the interface between screw and plate increased corrosion is observed. This phenomenon is stronger on the caudal side of the screw. Parallel to the in-vivo test the influence of stress load on the corrosion rate is analyzed for LAE442 in in-vitro tests. Compressive load is applied on cylindrical specimens in axial direction and the corrosion rate is measured in 0.9 wt% NaCl solution by eudiometry and mass loss. Additionally rectangular samples are bent to apply tensile stress on the surface. A drop of 5 wt% NaCl is deposited on the surface and the corrosion is evaluated by microscopic images. It is shown that stress essentially influences the corrosion rate. While tensile stress decreases the corrosion, compressive stress leads to higher corrosion rates.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/989
http://www.repo.uni-hannover.de/handle/123456789/1013
DOI:https://doi.org/10.1016/j.procir.2013.01.038
ISSN:22128271
Procedia CIRP 5 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10142022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:610ddc:600
Manufacturing conditioned wear of all-ceramic knee prostheses
Denkena, Berend
Köhler, Jens
Turger, Anke
Helmecke, Patrick
Correa, Tomas A.
Hurschler, Christof
Ceramic knee implant prostheses
Grinding
Polishing
Wear testing
Contact geometry
Geometrical accuracy
Grinding and polishing
Knee implants
Machining technology
Manufacturing process
Total knee joints
Wear-testing
Bioceramics
Grinding (machining)
Implants (surgical)
Joints (anatomy)
Sintering
Manufacture
ddc:600
ddc:620
ddc:610
Konferenzschrift
To date, bioceramics have not been applied successfully in total knee joint endoprostheses. Sintered bioceramics can be machined only by grinding and polishing processes. Due to high quality requirements, there are significant challenges with regard to these machining technologies. An automated precise economical process chain for the manufacturing of a new all-ceramic knee implant design was developed. It was assumed the geometrical accuracy and the shape of implant contact geometry specified during the manufacturing process has a substantial influence on the wear behavior of the prosthesis. The importance of the surface quality of the ceramic implant surface remains unclear and warrants future examination.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/990
http://www.repo.uni-hannover.de/handle/123456789/1014
DOI:https://doi.org/10.1016/j.procir.2013.01.036
ISSN:22128271
Procedia CIRP 5 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10152022-12-02T15:06:07Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Innovative drive concept for machining robots
Denkena, Berend
Litwinski, K.
Schönherr, M.
Drive chain
Machining
Robotics
Control loop
Harmonic drive
High resolution
Machining capabilities
Machining robot
Model-based control
Positioning tasks
Algorithms
Design
Dynamic loads
Equipment testing
Errors
Linear motors
Machining
Manufacture
Robotics
Torque motors
Servomotors
ddc:600
ddc:620
Konferenzschrift
In this paper an innovative drive concept for robots to improve their machining capability is presented. As a test bed a two-axis robot is designed and equipped with torque motors with load-sided high resolution encoders in addition to conventional gear motors with harmonic drive gearboxes. The gear motors are used for positioning tasks while the torque motors in particular compensate static and dynamic load-sided angle errors. The model-based control algorithm is decoupled and separately actuates both the servo gear and torque motors. It is shown that a considerable increase of performance is possible when adding the torque motors especially regarding the compensation of dynamic angle errors. The paper will present the design and details of the new drive concept, the modeling basics and first simulation results.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/991
http://www.repo.uni-hannover.de/handle/123456789/1015
DOI:https://doi.org/10.1016/j.procir.2013.06.170
ISSN:22128271
Procedia CIRP 9 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10162022-12-02T15:09:32Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessddc:330status-type:publishedVersionddc:620ddc:600
Stock market related pricing mechanisms for the tool and mould manufacturing industry
Denkena, Berend
Nemeti, Andrea
Enterprise related aggregation of knowledge
Prediction markets
Pricing
Time dynamic cost
Tool and mould manufacturing industry
Competitive factor
Knowledge aggregation
Mould manufacturing
Prediction markets
Pricing mechanism
Probability of occurrence
Time dynamic
Time-dependent dynamics
Commerce
Die casting
Dynamics
Industrial engineering
Industry
Manufacture
Molds
Production engineering
Tools
Costs
ddc:600
ddc:620
ddc:330
Konferenzschrift
Tool and mould manufacturers typically prepare their quotation provide an accurate price of, for example, a die casting mould is a key competitive factor for such companies. However, particularly in the customised production area, calculating the quotations and tenders has been proven as extremely challenging and subjective matter. One main cause is that time dynamic costs are rarely taken into consideration sufficiently even though they have a major impact on the final quotation due to the large time frame between the moment of the initial quotation and the actual production start. They neglect can lead to a significant discrepancy of up to 40 percent between pre- And post-calculation and thus to a loss of the corporate added value. A novel method developed at the Institute of Production Engineering and Machine Tools (IFW), Leibniz Universität Hannover, aims to provide a framework which allows tool and mould manufacturer to prepare a more precise and reliable quotation by taking time-dependent dynamic costs into consideration. The prediction of the time dynamic costs takes place by using stock market pricing mechanisms. Subsequently, based on enterprise related knowledge aggregation, this method also accounts for the probability of occurrence of each quotation thereby minimising the discrepancy between the pre- and post-calculation.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/992
http://www.repo.uni-hannover.de/handle/123456789/1016
DOI:https://doi.org/10.1016/j.procir.2013.09.071
ISSN:22128271
Procedia CIRP 12 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10172022-12-02T15:06:08Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:600
Modeling a thermomechanical NC-simulation
Denkena, Berend
Schmidt, A.
Henjes, J.
Niederwestberg, D.
Niebuhr, C.
Shape errors
Thermomechanical effects
Inverse projections
NC-simulation
Process simulations
Process temperature
Realistic simulation
Thermo-mechanical effects
Workpiece deformation
Heat flux
Machining centers
Tools
Virtual reality
Deformation
ddc:600
ddc:620
Konferenzschrift
This paper presents a method for a NC-Simulation based prediction of shape errors caused by thermal expansions in machining of complex workpieces. In the first part of the paper the basic approach of modeling a thermomechanical NC-Simulation for a faster and more precise process simulation is shown. Therefore, a fast dexel based material removal simulation including process models for calculation of localized heat flux and forces is linked to a FE model for simulation of thermal conduction in the workpiece. Interdependencies of thermal process and workpiece conditions are considered by a closed simulation loop. In the second part of the paper the modeling of each component is explained. To consider thermomechanical effects in material removal simulation the dexel based workpiece model is extended by additional information like temperature and deformation in every dexel. An inverse projection of the workpiece deformation on a triangulated tool model allows consideration this effect by deformation of the tool model. Thereby, a realistic shape of the workpiece can be simulated. In addition, the current cutting conditions like area of undeformed chip-thickness or contact length are changed. This results in diversified cutting forces and heat fluxes. For a realistic simulation of the thermal conduction the dimensions of the FE model have to be adapted by a time dependent virtual domain method. In the last part of the paper, results of the simulation are compared to measured data. The comparison shows that process temperatures in different workpiece areas are predicted accurately.
status-type:publishedVersion
Amsterdam : Elsevier
2013
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/993
http://www.repo.uni-hannover.de/handle/123456789/1017
DOI:https://doi.org/10.1016/j.procir.2013.06.067
ISSN:22128271
Procedia CIRP 8 (2013)
eng
CC BY-NC-ND 3.0 Unported
https://creativecommons.org/licenses/by-nc-nd/3.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10572022-12-02T16:17:36Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620
Energy consumption characterization in precision hard machining using CBN cutting tools
Grzesik, Wit
Denkena, Berend
Żak, Krzysztof
Grove, Thilo
Bergmann, Benjamin
CBN tool
Cutting energy
Hard machining
Ploughing energy
Tool wear
Energy balance
Energy utilization
Wear of materials
CBN tools
Cutting energy
Hard machining
Ploughing energy
Tool wear
Cutting tools
ddc:620
In this paper, the contribution of tool wear to the energy balance was determined for precision hard turning using chamfered CBN cutting tools. The tool nose wear VBC and the corresponding changes of component forces Fc, Ff and Fp resulting from tool wear evolution were continuously measured during wear tests. Based on the cutting mechanics, specific cutting and ploughing energies were calculated for a number of tool wear states. In particular, changes of energy balance due to tool wear under variable feed rate, depth of cut and tool nose radius were discussed. A distinction between material removal conditions resulting from precision cutting and grinding at a very low uncut chip thickness is considered. © 2015, The Author(s).
status-type:publishedVersion
London : Springer
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/1033
http://www.repo.uni-hannover.de/handle/123456789/1057
DOI:https://doi.org/10.1007/s00170-015-8091-1
ISSN:0268-3768
ESSN:1433-3015
International Journal of Advanced Manufacturing Technology 85 (2016)
eng
CC BY 4.0 Unported
https://creativecommons.org/licenses/by/4.0/
frei zugänglich
oai:www.repo.uni-hannover.de:123456789/10682023-02-08T10:07:04Zcom_123456789_1col_123456789_6doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:600
Simulation and Design of an Orientation Mechanism for Assembly Systems
Krebs, Daniel
Borchert, Gunnar
Raatz, Annika
assembly robot
cable-driven
orientation mechanism
parallel kinematic
Assembly
Cables
Degrees of freedom (mechanics)
Kinematics
Powertrains
Riveting
Assembly robots
Cable-driven
High-speed handling
Kinematic structures
Orientation mechanism
Orientation workspace
Parallel kinematics
Rotational degrees of freedom
Design
ddc:600
Konferenzschrift
The article focuses on methods for designing modular cable-driven orientation mechanisms that can be attached to robot systems that lack on rotational degrees of freedom. The approach yields assembly systems for high speed handling applications by reducing moving masses. For this purpose, a classification of feasible kinematic structures are given and resulting characteristics, like the orientation workspace, dexterity or its homogeneity, are analyzed. The mechanical design of a first prototype is subsequently presented along with a universal simulation tool for determining task-adapted powertrains using cables. Finally, results of first tests and possibilities for future developments are presented. © 2016 The Authors.
status-type:publishedVersion
Amsterdam : Elsevier B.V.
2016
doc-type:Article
doc-type:Text
http://dx.doi.org/10.15488/1044
http://www.repo.uni-hannover.de/handle/123456789/1068
DOI:https://doi.org/10.1016/j.procir.2016.02.122
ISSN:2212-8271
Procedia CIRP 44 (2016)
eng
CC BY-NC-ND 4.0 Unported
https://creativecommons.org/licenses/by-nc-nd/4.0/
frei zugänglich
oai_dc///col_123456789_6/100