Formulation and application of models for anisotropic hardening in sheet metals subject to complex loading-path changes

In this work material models for the simulation of forming processes involving non-uniform loading path changes are investigated. Materials exhibiting an evolution of the yield surface due to the formation and interaction of dislocation structures on the micro structural level are modeled by employing evolving structural tensors. These account for the evolution of anisotropy and hardening behavior known from technical alloys on a phenomenological basis. In a first step material parameters are identified from experiments for non-uniform loading conditions. In a second step, the evolution of structural tensors for varying loading conditions is investigated and related to the evolution of kinematic quantities. Finally applications relevant to the simulation of sheet metal forming processes are presented. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)