Performance of SMA-based damping devices with optimized hysteretic characteristics

An undamped SDOF system with a pseudoelastic SMA restoring force is investigated to find the optimal shape of the hysteresis loop of SMA elements which provides the maximum damping performance. The performance of the device is evaluated by the steady-state response at the resonance point in order to focus on the damping effect. Dynamic analysis utilizing the equivalent linearization approach results in two major findings: (a) for a given excitation amplitude, the scale of the hysteresis loop, which is a measure of displacement and restoring force, needs to be adjusted so that the response sweeps the maximum loop but does not exceed it; (b) the ratio of the area confined within the hysteresis loop, to the area of a corresponding envelope of triangular shape, should be as large as possible. Numerical study is carried out to verify the performance of the optimized devices subject to harmonic and random excitation. A simple mechanism that realizes the quasi-optimal hysteresis curve is shown as an example of possible devices.