横向冲击载荷下伪弹性TiNi合金矩形悬臂梁结构响应的实验研究

Experimental Study of the Dynamic Structural Response of Pseudo-Elastic Ti-Ni Alloy Rectangular Cantilever Beam upon a Transversal Impact

利用改装的霍普金森压杆装置对伪弹性TiNi合金矩形截面悬臂梁进行了横向冲击实验研究。结果表明:冲击自由端时,只在根部附近产生一个相变铰,冲击梁中间某位置时,则可能在多处形成相变铰;相变铰形成时拉伸和压缩两侧应变存在一定的不对称性,但是差别并不明显;相变铰的形成与发展过程中,应变并不是单调增加的,而是带有波动性;卸载后相变铰消失,TiNi悬臂梁形状完全回复;自由振动前期,应变的平衡位置与挠度的平衡位置有一定偏离,并且这种偏离随着梁的振动逐渐减小直至消失。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。

Experimental investigation of pseudo-elastic Ti-Ni alloy cantilever beam with rectangular cross-section under a transversal impact loading was conducted by using a revised Hopkinson bar apparatus. It is found that only one transformation hinge （TH） formed near the fixed end of Ti-Ni cantilever beam when the impact is applied at the free end, while several THs may form at different locations when the impact is applied on the middle of the beam; TH displays asymmetry on the both tension and compression sides, but the difference is not obvious. During the period of formation and development of TH strain increases not monotonously but with fluctuation. TH has disappeared after unloading and the Ti-Ni beam has recovered its original shape. During the early stage of free vibration, there are some differences between the equilibrium position of strain and deflection, which has decreased and finally disappeared along with the vibration of Ti-Ni beam. The impact response of Ti-Ni cantilever beams is controlled by the thermo-elastic martensite phase transformation and inverse transformation, which differs from the conventional elastic-plastic mechanism.