Constitutive Modelling of Viscoplasticity Incorporating Non-Proportional Hardening Effects

Abstract

The present paper is concerned with thee formulation of an elaborate constitutive model of non-proportional cyclic viscoplasticity. For this purpose, we first introduced the notions of memory surfaces for the kinematic hardening variable as well as for the isotropic hardening variable. Then by examining the cross-hardening phenomena induced by the torsional cycles after tension-compression cycles, we formulated the rational parameter describing the non-proportionality of the deformation process and the relevant evolution equations. The new model is established by incorporating these notices into the viscoplastic model proposed by Chaboche et al. Comparison of the predicted results with the corresponding experimental ones shows that the proposed model can describe the cyclic hardening behavior in various proportional and non-proportional loading conditions with constant and variable amplitudes.