Plastic energy and tearing energy of a NiTi shape memory alloy wire

A series of experiments were carried out to determine the plastic energy and tearing energy of a NiTi shape memory alloy wire by the multiple tensile testing (MTT) method. Both the austenitic and martensitic wires were tested at room temperature. Two strain rates, namely 10−3/s and 10−4/s were applied. It was found that at the higher loading rate of 10−3/s, the tearing energy and plastic energy are marginally higher. However, the plastic energy and tearing energy of the martensitic wire are much higher than those of the austenitic wire. The exact reason for the dramatic difference was yet identified, but it was observed that the austenitic wire breaks before a very large plastic deformation occurs.