A re-formulation of extended subloading surface model for cyclic plasticity within small strain framework: hyperelastic-based formulation and fully implicit return-mapping scheme

Abstract

This paper presents a re-formulation of the extended subloading surface model within the `unconventional plasticity' concept applicable to cyclic loadings. In addition to the usual additive decomposition of the small strain tensor into elastic and plastic parts, we primarily make a kinematic assumption in which the plastic strain tensor is further additively decomposed into an energetic and dissipative parts. The energetic part of the plastic strain is related to the back-stress for kinematic hardening via a hyperelastic-like constitutive equation without using a rate-type evolution law for the back-stress. Based on a similar idea, we introduce another additive decomposition of the plastic strain, and thereby a nonlinear evolution for the elastic-core tensor, i.e. a key internal variable in the extended subloading surface model, which stands for a stress state where the material exhibits most elastic responses, can be introduced in a reasonable way.