Influence of back stresses in parts forming on crashworthiness

The influence of back stresses during forming processes of sheet parts on subsequent crashworthiness is investigated in this article. To this aim, the simulation results of crash analysis applying material formulations with and without kinematic hardening are compared. It is found that the relevance of the back stresses in comparison with other variables defining the initial state of structural parts for the crash analysis varies depending on the amount of the plastic strain induced in the forming process. However, the influence of the back stresses during forming is not a priori negligible. For accurate and reliable simulations it is therefore recommended to incorporate and transfer the back stresses as well as other internal variables for the simulations of forming and crashworthy analysis.