A simplified constitutive model of Ti-NiSMA with loading rate

Abstract

This paper systematically studies the change law of the SMA (Shape Memory Alloy) stress-strain curve, stress at feature points, energy dissipation capacity and equivalent damping ratio with SMA diameter, strain amplitude, loading rate and the number of cyclic loading. As SMA’s dynamic mechanical property cannot be described in Brinson's SMA phenomenological constitutive model, an SMA simplified constitutive model, in which the influence of loading and unloading rate is considered, is introduced combined with the above test results. Then, this model is used to simulate SMA wires, and the obtained average error of all feature points at the stress-strain curve is only 3%. The results show that the established rate-dependent SMA simplified constitutive model can not only accurately describe the hyperelastic behavior of SMA during the phase change process induced by stress, but also reflect the influence of loading and unloading rate and strain amplitude on SMA’s dynamic constitutive model. This model has a simple structure and broad prospect in engineering application. Keywords: Shapememory alloy, Feature points, Equivalent damping ratio, Strain amplitude, Loading rate