Torsional vibration of a shape memory wire

The paper studies the rotational motion of a rigid mass suspended by a shape memory wire. The wire represents a torsional spring, which causes the mass to oscillate. At the same time, however, the wire induces damping through the hysteretic phase transitions that it undergoes during the oscillation. Due to the strong temperature dependence of the wire's thermomechanical properties, a complex behavior can be observed. The oscillation is shown to differ substantially depending on whether the wire is quasiplastic (low temperature) or pseudoelastic (high temperature). This provides a mechanism for an active control of the system. By an appropriate heating strategy, it is possible to compensate for the damping, and the oscillation can thus be stabilized. Received May 7, 1997