An Experimental Investigation on Training of NiTi-Based Shape Memory Alloys

Training of a shape memory alloy (SMA) is a process in which the mechanical response is stabilized. Since in real-world applications of an SMA, stress is variable and different from the training stress, in this paper we study NiTi-based SMAs’ response in higher and lower stresses than the training stress. In this work, six SMA wire samples were trained at stresses [Formula: see text] and 250[Formula: see text]MPa. Then, their recoverable strains were evaluated at a stress range of zero to 250[Formula: see text]MPa. Regarding the results, SMA wires which trained at 30, 150 and 200[Formula: see text]MPa exhibited a two-way shape memory effect (TWSME) behavior. Moreover, experimental tests showed that in stresses higher than 100[Formula: see text]MPa, recoverable strains are independent of the training stress, and to arrive at a better performance, training stresses higher than 100[Formula: see text]MPa are required. An unstable behavior was observed for SMA wires which were trained at 180[Formula: see text]MPa and 200[Formula: see text]MPa.