Impact protection behavior of NiTi shape memory alloy wires

This work studies the impact protection properties of both martensite NiTi wires and superelastic NiTi wires, with 0.5 mm diameter, at different initial impact energies using a new-designed impact test plant. In particular, impact experiments under a specific temperature range of As-Af, were performed for the martensite NiTi wires. The test results show that both the martensite NiTi wires and superelastic NiTi wires have excellent impact protection properties and can dissipate a significant amount impact energy compared to other more metal materials such as Cu, Fe, and Al. Otherwise, the martensite NiTi wires can dissipate more impact energy in a shorter period of time than superelastic NiTi wires while generating a smaller impact force, Fmax, due to their larger plastic deformation energy. Moreover, the dissipated energy, Wd, of martensite wires increases from 23.8 MJ/m3 to 53.6 MJ/m3, and the impact force, Fmax, increases from 42.96 N to 95.9 N, while the temperature rises from 35 °C to 65 °C. That means the impact protection properties of martensite NiTi wires are temperature dependent in a specific temperature range As-Af. Those results in this study also reveal that the impact protection properties of both martensite NiTi wires and superelastic NiTi wires represent the basis for new shape memory damping element applications, particularly in automotive safety systems.