JoiningTWIP project aims to support the introduction of TWIP-steels for automotive applications (in cars, trucks and buses) by identifying possible applications and further developing mechanical and low-heat joining technologies to be able to implement multi-material design with TWIP-steels. To guarantee a full view of the project team members from steel industry, car manufacturers, joining technology suppliers and universities are working together. This work describes the simulation stage of the different technologies. During the project, the materials described in the scope of the project were tested in order to obtain material characterization. Also, the different multi-material joints were tested to describe the joining process and the joining quality. These results will be used to build complex simulation models and prototypes, which show the performance and the behavior of the joining processes of TWIP-steels. Five different technologies were analyzed in the scope of the project: clinching, high-speed bolt setting, resistance element welding (REW), friction element welding (FEW) and flow drill screwing (FDS). To guarantee the performance of the simulation models, the results were compared to the sampled joint and processes. An optimization process of the different technologies was applied to improve the quality and the performance of the different joints.