Size, length, temperature and loading range effects on deformation response of NiTi SMA wire: an analytical study

摘要

Ni-Ti (Nitinol) wire is a novel material that possesses unique characteristics such as superelasticity, shape memory effect, recentering, high fatigue resistance, corrosion resistance, high damping characteristics, and high temperature-dependent Young's modulus. These wires exhibit distinct behaviors depending upon the range of temperature, strain loading, diameter, and length. With a purpose to dissipate the energy of vibrations, especially in cable-supported bridges, the hysteresis behavior of the Ni-Ti wire is required to be assessed. In this paper, the focus is to assess analytically the deformation responses of the Ni-Ti wire considering its superelastic and shape memory effects under the influence of temperature, size, length, and different strain loadings. Deformation behaviors of different sizes of Ni-Ti wire under various strain loadings are presented. The resulting symmetric and asymmetric response behaviors under tension and compression are highlighted. The typical hysteresis behavior representing the relationship between the transformation stress and strain is presented. It is found that the larger size of the Ni-Ti wire produces a bigger hysteresis area. Moreover, a shorter length of wire is more effective than a longer length. The temperature above 330 K of Ni-Ti wire plays a dominant role in eliminating the residual strain to regain the original shape.