NiTi合金伪弹性退化规律及尺度效应的试验研究

以NiTi合金在结构振动控制中的应用为背景,试验研究了加卸载循环次数和直径尺度对NiTi合金丝伪弹性特征的影响规律。研究结果表明,NiTi合金丝的残余应变随循环次数的增加呈指数关系增加,而其马氏体相变开始应力、奥氏体弹性模量、相变应变和等效阻尼比随循环次数的增加呈指数关系降低;随着直径尺度增加,循环加卸载后,NiTi合金丝的伪弹性退化程度显著增加。此外,残余应变与残余内应力、奥氏体弹性模量以及相变应变之间的线性关系揭示了NiTi合金伪弹性退化的内在机理。

Experimental Study of Pseudo-elasticity Deterioration Characteristics and Scale Effect of NiTi Alloy Wires

Taking NiTi alloy structure vibration control as background,the effect of cyclic loadingunloading times and wire diameter on the pseudo-elasticity characteristics of NiTi alloy wire was experimentally studied.Results show that along with the increase of cycle times,the residual strain of NiTi alloy wire increases exponentially,but the martensitic transformation stress,elastic modulus of austenite state,transformation strain and equivalent damping ratio decrease exponentially.Meanwhile,with the increase of cycle times,pseudo-elasticity degeneration of NiTi alloy increases obviously with the increase of wire diameter.In addition,the linear relationship among residual strain,residual internal stress,elastic modulus of austenite state and transformation strain reveals the internal mechanism of NiTi alloy pseudo-elasticity degeneration.