Rate dependent damping of single crystal CuAlNi shape memory alloy

We report the effects of loading rate and ambient condition on the damping capacity (energy dissipation) of superelastic CuAlNi single crystal shape memory alloy during stress-induced martensitic phase transformation. The roles of latent heat release/absorption and heat transfer between the specimen and the ambient in the specimen′s temperature and stress variations were investigated. The damping capacity in a tensile loading-unloading cycle was measured in the strain rate (ε̇) range of 0.0001/s - 1/s under three ambient conditions (still air and flowing air with velocities of 5 m/s and 17 m/s). Both the experiments and analysis showed that it is the temperature variation that makes the damping capacities change non-monotonically with the strain rate and that the maximum damping capacity (damping peak) is achieved when the loading time (tT) is close to the characteristic heat transfer time (th).