TiNi相变悬臂梁的横向冲击特性实验研究

Experimental study of the dynamic behavior of TiNi cantilever beams with phase transformation subjected to transversal impact

利用改装的霍普金森压杆装置对TiNi形状记忆合金圆截面悬臂梁进行了横向冲击实验研究,并与45#钢悬臂梁的实验结果进行了对比,目的是探索相变对结构动态响应的影响。结果表明:在同样冲击条件下,TiNi悬臂梁的吸能效率优于钢悬臂梁;发现冲击过程中,TiNi试件根部内侧可能形成局部"相变铰",使阻力曲线的斜率发生变化;卸载后"相变铰"消失,TiNi悬臂梁试件基本回复原状,钢试件则留下显著的残余变形。TiNi悬臂梁的冲击特性受热弹性马氏体相变和逆相变的支配,不同于传统的弹塑性机制。

The experimental investigation of TiNi cantilever with circular cross-section under transversal impact loading was conducted by using a revised Hopkinson bar apparatus, and compared to 45 steel cantilever. The purpose of this study is to explore the effect of phase transformation on the dynamic behavior of structures. The results show that at the same impact condition, the energy absorbing efficiency of a TiNi cantilever is better than that of a 45 steel cantilever. It is found that a local ＂transformation hinge （TH）＂ may generate at the inner side of TiNi cantilever＇s fixed end during im- pact loading, which changes the resistance characteristic of the cantilever. The ＂TH＂ disappears after unloading and the TiNi cantilever recovers to its original position, however, the 45 steel cantilever has large residual deformation. The impact response of TiNi cantilever is controlled by the thermo-elastic martensite phase transformation and inverse transformation, which differs from the conventional elastic-plastic mechanism.