弹簧指数对镍钛合金弹簧缓冲吸能能力的影响

Shape memory alloys (SMAs) springs have the ability to perform giant reversible strain, which is of great importance to the energy absorption buffer and vibration control applications. In this work, the influence of structure design on the performance of NiTi SMAs springs was studied. Ti-52.5at%Ni alloy wires with diameters of 1.2 mm were prepared by cold drawing and subsequent annealing, and springs with spring index C of 6.0, 7.7, and 9.3 were prepared by mandrel wound molding and subsequent high temperature annealing. The energy absorption performances of the springs were studied by testing the superelastic curves of the alloy wires and springs. The results show that, based on the superelastic processes, the energy absorption capacity per unit volume of the three types of springs at room temperature (298 K) is 4618, 2225 and 1143 kJ/m³ at a maximum displacement amplitude of 120 mm, where the spring with spring index C of 6.0 has the best energy absorption capacity. Furthermore, the energy absorption per unit volume of spring with spring index C of 6.0 reaches 6662 kJ/m³ at 318 K due to its full austenite state, which is 192 times higher than that of the alloy wire (34.7 kJ/m³) under the same load (47 N), meaning that under same condition, the spring structure has better energy absorption capacity than that of the alloy wire. Therefore, the superelastic SMAs springs may show great potential in the future application of damping structures.