Thermo-mechanical properties of snake-like NiTi wires and their use in miniature devices

In this study, we present the thermo-mechanical characterization of snake-like shape memory alloy (SMA) NiTi wires. Several samples were formed at different thermal treatments and analyzed through calorimetry and thermo-mechanical tests. It was found that for small deformations the snake-like SMA wire behaves as a quasi-elastic material, presenting the flag-shape pseudoelastic behavior at high thermal treatment temperatures. The mechanical performance seems to depend basically on the snake geometry instead on the thermal treatment; only for the 773 K treatment sample the performance rapidly gets worse. Stabilization is reached in few cycles. After the thermo-mechanical characterization, we studied the performance of the snake-like SMA wire mounted in a miniature rotational actuator, suggesting an innovative application in the actuator field.