The role of plasticity in the integrated approach of subsequent simulations of car structures

In the development of car structures the performance (i.e. dynamic behavior, fatigue life) is analyzed by prototype testing and simulation. Nowadays, the simulations are based on the geometry that is obtained directly from the CAD construction. It is known however, that forming can change the material performance considerably. To improve the accuracy of the virtual model the irreversible effects of the forming operations must be integrated by means of coupling the successive operations in a virtual process chain. Therefore all previous forming and joining steps must be evaluated and results must be transferred to the next step. Opposite to standard models now the real thickness of sheet metal parts and residual stresses due to forming and joining and the changed material parameters at every point are known prior to applying any service loads. This results in a more reliable prediction of product performance. In this paper it is demonstrated how the performance of chassis parts changes with the inclusion of plastic forming effects compared to neglecting them. This involves the transfer from results of the forming process to the comprehensive model. The joining to (sub-)assemblies of the different parts is included in a parameterized way. Hereafter the model will be subjected to static and dynamic external loads and compared to calculations using a standard model. The results clearly show that the inclusion of the plastic history has a significant influence on the product performance.