Influence of Discretisation on Stiffness and Failure Prediction in Crashworthiness Simulation of Automotive High Pressure Die Cast Components

Castings are widely used as part of the car chassis in automobile manufacture because of their light weight and the flexibility of the design process. Due to the comparable low ductility of castings, it is essential for crash simulations to gain dependable analyses. However, modelling casting parts correctly for finite element analyses is an issue for several reasons. In order to represent the elastoplastic stiffness correctly and thus to obtain reliable failure predictions, an accurate prediction of plastic strains and the corresponding stress states is required. To meet these conditions an adequate material and failure model is needed. Besides the characterisation and modelling of the material, the geometric discretisation is a trade-off between computational costs, meshing effort and the quality of the results that can be achieved in simulations. Typically, no general guidance is provided on the appropriate element formulation or the impact this choice may have on the results. Lastly, in industrial environments economic competition usually does not allow for extensive basic research. Conservative methodologies in development and simulation of castings are the norm since new methods carry the risk of failure. Thus avenues of improving accuracy and reducing costs of simulations remain to be explored.