Damage Modelling of Automobile Components of Aluminium Materials under Crash Loading

A. Ockewitz, D.-Z. Sun (Fraunhofer IWM); H. Klamser, D. Malcher (Dr. Ing. h.c. F. Porsche) The crash behaviour of automobile components from an aluminium die cast alloy and from an extruded profile was characterised under different load conditions and simulated with two damage models (Gurson, Johnson-Cook). The influences of the stress triaxiality and strain rate on the deformation and damage behaviour were taken into account in the experimental and numerical investigation. The Gurson model was extended to simulate shear failure by using an additional failure criterion for the region between pure shear and uniaxial tension. To verify the damage models component tests under crash relevant loadings were performed and simulated with the damage parameters which were obtained by modelling the tension and shear tests on small scale specimens. The Gurson model and the Johnson-Cook model were compared with regard to the applicability of the damage parameters for different stress triaxialities. It was found that the Gurson model with the parameters from tension tests can be also applied to local loading situations with high stress triaxialities while the Johnson-Cook model requires additional fracture mechanics tests to determine the corresponding fracture strains for this kind of application.

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