Hardening Models and Their Predictions of Material Response

Abstract

Several hardening models are investigated in this paper to examine how they predict material behavior under closed-loop loading paths. The linear Prager's kinematic hardening rule and a new kinematic hardening model proposed in a previous paper are first used to solve a thin-walled tube problem subjected to combined internal pressure and axial loads. Closed-form transient and steady-state solutions are achieved for closed-loop loading paths, and the corresponding yield center loci and plastic strain trajectories are illustrated. This paper then shows that Phillips's kinematic hardening rule and the two-surface plasticity theory all predict an unreasonable material response. A conclusion is finally reached that the newly proposed kinematic hardening model has more potential than the other models, and further theoretical and experimental investigations are suggested to probe the optimum form of the plastic modulus to make this new model qualitatively, and also quantitatively, describe well material behavior.