Plasticity Effects in Subsequent Simulations of Car Structures

In order to further reduce the weight of car components while at the same time maintaining performance and safe life it is necessary to enhance the simulation process. This is especially important for chassis parts which have not only a high dynamic load but are also partly undamped. To reach this goal, the logical step is to couple the successive operations of forming, assembly and virtual performance testing. The objective is a complete determination of the mechanical state of the (sub-)assemblies. It is therefore necessary to consider all forming and joining processes a part has previously undergone and to consider them in the virtual model. This virtual model is ideally suited for virtual prototyping (e.g. structural analysis, fatigue, crash) because the complete history of every part is contained. In contrast to standard models, the changed thickness of sheet metal parts and residual stresses due to forming and joining as well as the new material state at every point are known prior to any external loading. This results in a more reliable prediction of product performance. Using a relatively simple part it is demonstrated how the performance of chassis parts changes with the inclusion of plastic forming effects as compared to the exclusion of these effects. The transfer of the results of the forming process to the comprehensive model is shown first. Hereafter the model is subjected to static and dynamic external loads. The results are compared to calculations that use a standard model and show clearly that the inclusion of the plastic history has a significant influence on the product performance. Kim Kose and Bert Rietman