Testing of Formed Gear Wheels at Quasi-Static and Elevated Strain Rates

Abstract

Geared components can be manufactured from sheet metals by sheet-bulk metal forming. One relevant load case in service are overload events, which might induce elevated strain rates. To determine the characteristic hardening and fracture behavior, specimens manufactured from the deep-drawing steel DC04 were tested with strain rates ranging from 0.0001 to 5 s−1. The gear wheels manufactured by sheet-bulk metal forming are tested at crosshead velocities of 0.08 mm/s and 175 mm/s. The tests are analyzed by measuring deformed geometry and hardness. While the tensile tests results show obvious strain-rate dependency, the hardness measurements show no strain-rate depended effect. The analyses are complemented by finite-element-simulations, which assess the homogeneity of deformation and point out the mechanisms of failure. Both coupled and uncoupled ductile damage models are able to predict the critical areas for crack initiation. The coupled damage model has slight advantages regarding deformed shape prediction.