Feasibility study on a superelastic SMA damper with re-centring capability

Superelastic shape memory alloys (SMAs) have the ability to recover their original shape after experiencing large strains. By exploiting this unique characteristic of SMAs, this paper presents a new SMA-based damper mainly consisting of pre-tensioned superelastic SMA wires and two precompressed springs, which function as energy dissipation and re-centring group, respectively. The pre-tensioned SMA wires and roller system offer the damper an enhanced stroke and high-energy dissipation capacity, while the precompressed springs supply the damper with an expected restoring force. With maintaining the precompression imposed on the springs equal to the initial reaction force gap for two groups of SMA wire loops at a minor move of middle anchor, the damper shows both good energy dissipation capacity and full re-centring capability. A validity study is conducted by using the Brinson's constitutive model of SMA material. The results demonstrate that the equivalent damping ratio of 0.12, stoke of 30 mm and full re-centring capability can be achieved in a 1 m long SMA damper.