Numerical and Experimental Investigation on Electro-Thermo-Mechanical Behavior of NiTi Shape Memory Alloy Wires

Electric heating of shape memory alloys (SMAs) is of great importance since it is one of the fastest ways to heat these alloys, especially in actuator applications where time response is important. Consequently, it is crucial to be able to predict the electro-thermo-mechanical (ETM) behavior of such materials. In this paper, ETM behavior of NiTi SMA thin wires under variable applied stresses is experimentally and numerically studied. A one-dimensional incremental formulation of an SMA ETM model, which has been previously derived in continuum mechanics framework, is implemented to predict the ETM response of SMA wires during electromechanical loadings. This 1-D model is able to account for both shape memory effect and the pseudoelasticity. A special test setup is prepared, and experimental responses under different loadings are examined. The results confirm the reliability of the model when the numerical strain–time responses are compared with the experimental findings at several electromechanical loading conditions.