Experimental Investigation on Superelastic Behaviors of NiTi Shape Memory Alloy Cables with 7×19 Sections

This study aimed to investigate the cyclic tensile behavior of 7×19 NiTi shape memory alloy (SMA) cables with a single wire diameter of 1.0 mm, in order to optimize their superelastic properties for engineering applications. A comprehensive analysis was conducted to assess the effects of various factors, including heat treatment strategy, strain amplitude, number of cycles, pre⁃training, and loading rate on the mechanical parameters of SMA cables. The obtained mechanical parameters, such as residual strain, energy dissipation, equivalent viscous damping ratio, strength, and stiffness were examined under different conditions. The results showed that the annealing temperature of 400 ℃ for 10 minutes produced the highest phase transformation stress and recovery rate for the 7×19 SMA cable configuration, which deteriorated with prolonged annealing time. The deformation and stress development of the single wire inside the SMA cable are more uneven, and the hysteresis curve has no obvious phase transformation platform. The initial elastic modulus and ultimate stress of SMA cables under constant amplitude tension are relatively small, while the degradation of phase transition platform height, recovery rate and equivalent viscous damping ratio is obvious. Moreover, the pre⁃training method can reduce the functional damage of the SMA cables, significantly reduce the residual deformation, and improve the recovery ability. The loading rate has a great influence on the martensitic stress and the tangent modulus of the yield platform of the SMA cables. When the loading rate exceeds 1×10-2 s-1, the hysteresis curve is not sensitive to the change of the loading rate. The results provide experimental data support for the application of 7×19 section SMA cables. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.