Experimental studies of training stress effect on NiTi SMA performance in higher and lower stress than training stress

SMA training in constant stress causes stabilized response. Since in engineering applications alloy stress isvariant،the aim of this study is to investigate SMAs response in some range of stresses. In this study، six SMA wires were trained in 30، 50، 100، 150، 200 and 250 MPa. At the next step، their recoverable strains were evaluated in 0-250 MPa. It was found that SMA wires that trained in 30، 150 and 200 MPa showedtow-way shape memory effect (TWSME). Also recoverable strains in stresses higher than 100 MPa are independent of training and in order to have better performance، stresses higher than 100 MPa are required. SMA wires trained in 180 and 200 MPa resulted in unstable behavior.