A new simplified distortional hardening model for nonlinear strain paths

Abstract

The material behaviors under nonlinear strain paths have been successfully explained through distortional hardening model in which the yield surface is mainly rotating and contracting as plastic deformation occurs. In order to apply to industrial applications, it is beneficial for any constitutive model including distortional hardening model to have simplicity of equation, which is related to numerical efficiency, as well as accuracy in describing material behaviors. This study was mainly motivated to construct a simple form of equation for distortional hardening model with reasonable accuracy as the conventional distortional hardening models. In this paper, a new simplified distortional hardening model is proposed by considering one of the pioneering works for distortional hardening (Tozawa, 1978) and definition of homogeneous function. Any yield function could be used for initial anisotropy and asymmetry yielding. In addition, with the combination of isotropic hardening model for consistency condition, the new model could explain both isotropic and anisotropic hardening under proportional and non-proportional loading paths. The proposed model reasonably described the material behaviors including Basuchinger effect, permanent softening, nonlinear transient behavior, and yield surface contraction. Finally, the availability in finite element simulation has been identified from the springback prediction in U-draw bending.