On modelling phase propagation in SMAs by a Maxwellian thermo-viscoelastic approach

In this paper we propose a Maxwellian thermo-viscoelastic approach to the problem of phase transformation in shape memory alloys. An explicit temperature-dependent non-monotone piecewise linear stress–strain relation is considered and the corresponding free energy function is used to establish the heat propagation equation. The heat exchange between the material and its environment is also taken into account. The numerical simulations of three end-displacement rates lead to serrated hysteresis loops and result in inhomogeneous deformations and exothermic/endothermic behavior during loading/unloading tests. It is shown that the influence of the strain rate on the size and shape of the hysteresis loop is due in fact to the heat exchange between the bar and its environment. The predictions are compared qualitatively with experimental results.