Numerical simulation of a double SMA wire actuator using the two-way shape memory effect of SMA

A structure using the two-way shape memory effect (TWSME) returns to its initial shape by increasing or decreasing the temperature under initial residual stress. Through the thermo-mechanical constitutive equation of the shape memory alloy (SMA) proposed by Lagoudas et al (1996 Mech. Compos. Mater. Struct. 3 153–79), we simulate the behavior of a double SMA wire actuator in which two SMA wires are attached to the tip of a bar under the initially given residual stress. Through the numerical results conducted in the present study, the behavior and characteristics of an SMA actuator with two SMA wires are shown to be quite different from those of a single wire actuator, and the proposed actuator device is suitable for repeated actuation. A thermal cycle needs to be applied to the double SMA wire actuator for it to return to the original position. The proper thermal cycle for repeated actuation is proposed in the present study. The simulation algorithm proposed in the present study can be applied extensively to the analysis of the assembled system of SMA actuator and host structure in practical applications.