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Shape memory alloy (SMA) wires are becoming potential candidates as actuators due to their high stress-generating and strain-recovery capabilities. As actuators, these wires undergo arbitrary thermo-mechanical loading. For an efficient design, one requires a model to simulate their behavior under any stress–temperature situation. In this study, based on an existing phase kinetics dependent phenomenological model, an algorithm capable of simulating SMA wire behavior under an arbitrary loading situation has been developed and implemented. To demonstrate this, two cases have been simulated. In the first case, the behavior of an SMA wire undergoing varying stress and temperature while actuating a single degree of freedom manipulator has been simulated. The results are found to illustrate the discrepancies reported in the literature. The behavior of two antagonistically placed and independently activated SMA wires is modeled and simulated in the second case, where the results qualitatively agree with the existing experimental results.

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This paper presents forward and inverse analyses of the response of a compliant link actuated by a discretely attached shape memory alloy (SMA) wire subjected to a time-varying input voltage. The framework for a constrained recovery of the shape memory alloy wire is developed from a robust numerical model. The model for the large deflection of a beam element due to follower forces resulting from discrete actuation using a SMA wire is coupled with the proposed framework. Thus, the response of the link is correlated with the input voltage. The algorithm for implementing this framework has been demonstrated along with some numerical examples. Experiments have also been conducted on a SMA actuated cantilever beam, and the results are compared with those of the simulations. A qualitative agreement between the two is observed. It is concluded that the theoretical results can provide a reference signal for active control of the link to achieve higher accuracy.

For discrete actuation with shape memory alloy (SMA) wires, the actuation moment can be controlled by changing the amount of wire offset. Increasing offset not only enhances the actuating moment, but also demands larger displacement capability of the actuator. In this paper, large deflection of a cantilever beam actuated by a SMA wire has been investigated. Both the theoretical and experimental results reveal the existence of an optimum offset maximizing the end deflection. The optimum offset depends on the flexural stiffness of the beam, SMA wire properties, and the input actuation level.

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