Ambient effect on damping peak of NiTi shape memory alloy

Abstract

We report the effects of ambient condition and loading rate on the damping capacity of a superelastic nickel–titanium shape memory alloy during stress-induced martensitic phase transformation with release and absorption of latent heat. The damping capacity was measured via a tensile loading–unloading cycle in the strain-rate range of 10 − 5 –10 − 1 / s and three ambient conditions: still air and flowing air with velocities of 2 m/s and 17 m/s. It is found that, for each ambient condition, the maximum damping capacity (damping peak) is achieved at the strain rate whose loading time ( t T) is close to the characteristic heat-transfer time ( t h) of the ambient condition.