An equivalent local constitutive model for grain size dependent deformation of NiTi polycrystalline shape memory alloys

In this paper, an equivalent local constitutive model is constructed to describe the grain size dependent deformation of NiTi polycrystalline shape memory alloys (SMAs). The aim of such a model is to convert the existed microscopic nonlocal model into a macroscopic local one and ensure them to be equivalent in energy and dissipation. Firstly, based on the experimental observations, an existing nonlocal model is simplified and the analytical solution for the evolution of martensite volume fraction is derived. Then, an energy-equivalent rule is proposed and the scaling law of transformation hardening modulus is obtained. Finally, with the help of proposed scaling law, a macroscopic local model is constructed from the irreversible thermodynamics. The capability of the local model to describe the grain size dependent deformation of polycrystalline NiTi SMAs is verified by comparing the simulations with corresponding experimental results [7]. (C) 2018 Elsevier Ltd. All rights reserved.