SMA丝材回复性能试验研究

Experimental Study on the Recoverability of SMA Wire

为研究SMA丝材的回复性能,文章采用形状记忆合金制作了试件,对其进行了不同初始应变下试件的循环荷载和温度往复试验,获得了应力-应变关系曲线,分析了循环次数、应变幅值、加载速率、温度对SMA丝材的回复性能的影响。试验结果表明,SMA丝材经过10次循环加卸载后的残余应变量与第1次加卸载后的残余应变量几乎一致,材料的形状记忆效应表现明显;在小应变幅值下,SMA丝材的应力增长较快;在中等应变幅值下,SMA丝材的应力几乎不变;在大应变幅值下,SMA丝材已经进入强化阶段,应力继续呈线性增加;SMA丝材的最大回复力在一定范围内和预应变值成正比,在高温奥氏体相变完成后,回复力趋于稳定;8%预应变值的SMA丝材升温到奥氏体状态所提供的回复力值最高可以达到514 MPa,循环30次后的SMA丝材仍能够提供稳定的回复力。

In order to study the recovery performance of SMA wire,the shape memory alloy(SMA)specimens were made in this paper.Cyclic load and temperature reciprocating tests were carried out on the specimens under different initial strains,and the stress-strain relationship curves were obtained.The effects of the number of cycles,strain amplitude,loading rate and temperature on the recovery performance of SMA wire were analyzed.The test results show that the residual strain of SMA wire after 10 cycles of loading and unloading is basically the same as that of SMA wire after the first loading and unloading,and the material presents an obvious shape memory effect;Under small strain amplitude,the stress of SMA wire increases greatly;At medium strain amplitude,the stress of SMA wire hardly increases;At large strain amplitude,SMA wire has entered the strengthening stage,and the stress continues to increase linearly;The maximum restoring force of SMA wire increases with the increase of prestrain in a certain range,and tends to be stable after the completion of high temperature austenite transformation;The SMA wire with 8%pre strain value can provide a maximum recovery force of 514MPa when it is heated to the austenitic state.The SMA wire can still provide a stable recovery force after 30 cycles.