Kinematic hardening model considering directional hardening response

Abstract

This paper proposes a kinematic hardening model to capture both asymmetric plastic behavior (early-reyielding, transient Bauschinger effect and permanent softening) and directional hardening (anisotropic hardening) response at the same time. The previously reported kinematic hardening models have brought significant improvements of ability to describe the asymmetric plastic behavior of sheet metal in cycling loading conditions at fixed one angle from the rolling direction (RD). However, their inability to cover the anisotropy in the directional hardening response has a limitation to describe the anisotropic hardening behavior because material constants of general kinematic hardening models are only fitted to one reference axis. In order to capture the anisotropic hardening with a kinematic hardening model, this work proposes a scheme to combine a kinematic hardening model with a function, which is called the condition function in this paper, to account for the change of the mechanical property with respect to the RD. The condition function should explicitly capture four independent hardening data in different directions, 0 degrees, 45 degrees, 90 degrees to the RD and the equal biaxial (EB) condition in order to gain an appropriate parameter set. The new model is validated with four tests and the results are compared with other material models to clearly show that the new model can capture both the anisotropic hardening response and the asymmetric plastic behavior for monotonic and cycling loading conditions.