Pseudo Elastic and Self-healing Cyclic Properties of Smart NiTi Shape Memory Alloy for Seismic Mitigation

Abstract

This research highlighting the novel properties of pseudo-elastic Ni-Ti bar owing to their ability to reverse macroscopically inelastic deformation during earthquake known as recentering capability and large elastic strain capacity which originated from the reversible austenite to martensite phase transformation. Hence, this paper presented and evaluates the cyclic properties of pseudo elastic Ni-Ti shape memory alloys to assess their prospective use for seismic applications to be exploited as seismic resistant design and retrofit. In addition, the correlation of hysteretic behavior of Ni-Ti alloy in terms of cyclic loading number and history, mechanical properties at ambient temperature, equivalent damping, energy dissipation and recovery stress were evaluated. The NiTi bar with weight percentage of Ti-43.98 at. % Ni 56.02 and diameter of 12mm. The tensile cyclic test obtained demonstrated a rounded loading curve based on a 0.2% offset. The NiTi bar exhibited superior pseudo-elastic behaviour and recentering through repeated cycling without significant degradation or permanent deformation but low energy dissipation due to narrow hysteresis while the steel rebar shows vice versa. Experimental results show potential for the use of SMAs in seismic applications and provide areas for continued research. It was concluded that the as-received pseudo elastic Ni-Ti bar is suitable use for seismic mitigation despite of their ability to undergo cyclical strains is 6% which is greater than 5%, with minimal residual strain, 0.01% which is less than 1%.