Dynamics of a Mechanical System with a Shape Memory Alloy Bar

Abstract

We study the dynamics of a simple mechanical system containing a mass and a bar made of shape memory alloys. Our objective is to understand the effect of stress induced phase transtormation on the system dynamics. Specifically, the effectiveness of an idealized vibration isolator made of shape memory alloys is examined both numerically and experimentally. We find that the stress induced phase transformation within the material has two effects: the resonance frequency of the system is lower and the peak response near the resonance is heavily suppressed. Furthermore, both of these effects depend on the forcing amplitude and they are more pronounced at large forcing amplitudes. We also find that nonlinearity associated with the phase transformation gives rise to complicated dynamics. In particular, period-three responses are found for some forcing parameters. It the case of a biased load, period-doubling cascade and chaotic motion can occur. However, this complicated dynamics disappears at large forcing amplitudes, making the shape memory alloy vibration isolator an effective device at large forcing amplitudes.