Process-oriented validation of hardening models in a cyclic bending test

Abstract

In terms of forming processes with complex stress histories, like operations with drawbeads, the implementation of a kinematic hardening rule can significantly improve the numerical prediction quality. However, the variety of mathematical formulations and the non-standardized identification methodology make a preliminary evaluation of the models with respect to their subsequent application necessary. The use of a cyclic bending test is a very flexible and robust technique to validate material models. In view of the bending-like load distribution during a drawing operation of an open shape, this test allows a process near emulation of the forming history. Within this contribution, the realization of a defined strain history-derived form a deep drawing process with draw beads-is presented. For the high-strength steel HCT780X and the aluminum alloy AA6014-T4 an isotropic hardening rule as well as the extension with a kinematic hardening model according Chaboche and Rousselier are evaluated. The result's transferability is finally analyzed on basis of the springback calculation of the deep drawing operation.