Numerical investigation of the influence of preliminary manufacturing processes on the crash behaviour of automotive body assemblies

摘要

The simulation of the crash behaviour of whole automotive body structures has gained increasing value in the development phase of the overall product cycle in the recent years. In the automotive body-in-white cost and time as well as high accuracy and quality of structural components are main issues. Particularly, when it comes to safety matters, the crash behaviour of the overall vehicle shell is a major concern. So as to describe the manufacturing process chain more precisely and to predict the structural behaviour at early stages of product and process planning, an interlinking of forming, trimming and welding models within a structural manufacturing computation chain is necessary. The computed structural properties after manufacturing and joining of body assemblies appear to be essential for a more accurate description of the actual crash behaviour. Considering the structural properties after the forming and trimming process for simulating welding tasks and finally the crash behaviour requires a multifaceted modelling method. In this paper, a practicable strategy for realising the simulation chain forming-welding-crash of whole structural assemblies by means of shell element models is introduced. The complete computed results of a forming process simulation, such as residual stresses, plastic strains, and material thinning are transferred into the simulation of welding heat effects. Further on, the structural properties after forming combined with the thermal distribution due to the welding process and the mechanical clamping conditions within a thermomechanical computation allow a conclusion on the final shape, residual stresses and plastic strains in the weld seam area of the manufactured structure. Finally, the attained structural results are converted into the required data format by means of a developed conversion routine, which enables the side crash simulation of a sill board assembly automotive structure on a rigid pole considering the entire preliminary manufacturing process chain.