An Investigation on Spotweld Modeling for Crash Simulation with LS-DYNA

Because of weight reduction necessities, high-strength steels are more and more widely used in bodyin-white (BiW) structures in recent years. Concerning the behaviour of such structures during a car crash the joints between high-strength materials are seen as critical points. Therefore the properties of welded joints, especially the failure behaviour at high velocities have to be taken into consideration during the development phase. In this paper, we present an overview on the current activities at the DaimlerChrysler AG regarding investigations on spot weld failure behaviour. A suitable model that is able to represent the failure behaviour of spot welds in BiW structures and that is independent of mesh sensitivity has been developed. An elasto-plastic material model based on von Mises plasticity (MAT_100) has been further enhanced with a new failure criterion. The model has been implemented into LS-DYNA. The material as well as the failure behaviour is verified and calibrated through precision experiments conducted on specimen level and later validated on component level.