Shape Memory Alloys: identification of the parameters necessary for constitutive models

Abstract

The purpose of this research is to identify the Shape Memory Alloy (SMA) parameters necessary for SMA actuators analysis using SMA constitutive models. The behavior of a material is primarily a function of three variables: stress, strain and temperature, and their associated rates. These variables are interdependent, and the material behavior is a non-linear function of these variables. A number of constitutive models for shape memory alloys have been proposed and found to be relatively convenient to use in predicting and describing shape memory alloys’ behaviors quantitatively. However, the application of these models in designing and analyzing an actuator requires the determination of the thermomechanical properties of these materials such as transformation temperatures, thermoelastic tensor, Young’s modulus, Transformation tensor) and recovery strain. This research has been conducted to identify the thermomechanical properties of a commercial NiTi SMA wire. The paper shows in details how these parameters can be identified.