Damage modelling of a TRIP steel for integrated simulation from deep drawing to crash

The local mechanical properties e.g. flow stress and fracture strain in an automotive component manufactured by deep drawing are inhomogeneous due to different local deformation degrees which affect the component behaviour under crash loading. A reasonable approach for modelling the damage behaviour of a component produced by deep drawing is a coupling between forming simulation and crash simulation. The open questions are which material model (kinematic or isotropic hardening) and which damage model should be used for an integrated simulation. Since the loading type is mainly biaxial at deep drawing and uniaxial under crash, it should be investigated how the damage development is influenced by deformation history including change of stress state. In this work the influence of triaxiality and pre-deformation on damage behaviour of a TRIP steel was characterized with different specimen tests e.g. under shear, uniaxial and biaxial tension and a damage model taking into account shear fracture and dimple rupture was developed. This damage model can also describe the influence of pre-deformation. Validation tests on an automobile component under a loading close to reality were performed and simulated with pre-strains and pre- damage mapped from a forming model to the crash model.

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