Phenomenological modeling of shape memory effect using the concept of orientational back stress

Abstract

A derivation of constitutive equations in a general three-dimensional setting is described, based on an additive decomposition of the rate of deformation tensor. The rate of deformation tensor is assumed to consist of an elastic part, a thermoelastic part, a plastic part, and a part due to phase transformation. The thermoelastic part due to thermoelastic coupling accounts for the influence of temperature near phase transformation, while the plastic part is taken in the form of classical flow theory of plasticity with combined isotropic and kinematic hardening, where the back stress represents a tensor of orientational micro-stresses. It is assumed that the part due to the phase transformation depends on the first and the second invariant of the tensor of crystallographic distortion, on the deviatoric part of the stress tensor, and on a special evolution parameter describing the rate of forming of a new phase. The derived constitutive equation is given in an explicit form with the corresponding tensor generators of the representation together with the irreducible integrity basis of the relevant tensor functions.