To date, research on the physical and mechanical behavior of nickel-titanium shape-memory alloy (NiTi SMA) has focused on the macroscopic physical properties, equation of state, strength constitution, phase transition induced by temperature and stress under static load, etc. The behavior of a NiTi SMA under high-strain-rate impact and the influence of voids have not been reported. In this present work, the behavior evolution of (100) single-crystal NiTi SMA and the influencing characteristics of voids under a shock wave of 1.2 km/s are studied by large-scale molecular dynamics calculation. The results show that only a small amount of B2 austenite is transformed into B19’ martensite when the NiTi sample does not pass through the void during impact compression, whereas when the shock wave passes through the hole, a large amount of martensite phase transformation and plastic deformation is induced around the hole; the existence of phase transformation and phase-transformation-induced plastic deformation greatly consumes the energy of the shock wave, thus making the width of the wave front in the subsequent propagation process wider and the peak of the foremost wave peak reduced. In addition, the existence of holes disrupts the orderly propagation of shock waves, changes the shock wave front from a plane to a concave surface, and reduces the propagation speed of shock waves. The calculation results show that the presence of pores in a porous NiTi SMA leads to significant martensitic phase transformation and plastic deformation induced by phase transformation, which has a significant buffering effect on shock waves. The results of this study provide great guidance for expanding the application of NiTi SMA in the field of shock.

Transmission tower plays important role in the power system and it is security sensitive in various working conditions, such as wind and ice. In this paper, a method to obtain the dynamic response of a cat head type transmission tower under strong fluctuating wind was proposed. The coupled tower-lines finite element model was established in ABAQUS, and the equivalent acceleration of fluctuating wind was simulated by MATLAB. Then the displacements and stresses time histories were obtained. The method introduced in this paper can be used to assess the safety of tower under different fluctuating wind with different directions and provide a reference of the tower in the design stage.

In this study, the whole assembly process from pre-treatment to service of NiTiNb shape memory alloy (SMA) pipe-joint system is numerically simulated by using of the finite element method. With the change of the wall thickness of SMA joints and the pipe outer diameter, the contact pressure and pull-out force under different interferences and pipe diameter ratios are calculated. The results show that the contact pressure between the joint and the pipe increases with the increase of pipe thickness under the same NiTiNb-SMA joint. With the decrease of the joint's wall thickness, the contact pressure reduces. The pull-out force does not increase with increasing SMA joints' outer diameter and has a very slightly decrease with the increase of temperature.