镍钛形状记忆合金丝的性能测试分析

从形状记忆合金（ Ｓ Ｍ Ａ）的性能测试和智能材料与结构研究的角度出发，论述了 Ｓ Ｍ Ａ 驱动元件的应力、应变、温度和相变之间的测试关系，并通过分阶段和不同的变量组合，对直径０．５ｍ ｍ 的 Ｎｉ Ｔｉ Ｓ Ｍ Ａ 丝（ Ｎｉ４９．２％ ａｔ Ｔｉ）的基本驱动特性进行了系统的测试分析，测试内容主要集中于相变温度、自由状态下的最大回复应变、约束状态下的回复应力等。结果表明， Ｎｉ Ｔｉ Ｓ Ｍ Ａ 丝的应力应变温度关系呈现出高度的非线性，环境温度和外加应力是影响 Ｎｉ Ｔｉ丝性能的主要因素，外载荷将使相变温度升高；约束回复中，随着约束应变量的增大和温度的升高， Ｎｉ Ｔｉ丝的回复应力也增大。该测试结果为更好地监测和控制 Ｎｉ Ｔｉ Ｓ Ｍ Ａ 的驱动行为、设计 Ｓ Ｍ Ａ 驱动元件提供了参考依据。

Measurements and Analyses for Properties of NiTi Shape Memory Alloy Wires

The testing methods for shape memory alloy (SMA) are proposed based on material evaluation technology and requirement of smart materials and structures.The important relationships among strain, stress, resistance and temperature of NiTi SMA wires (Ni 49.2% at Ti , 0.5 mm in diameter) are synthetically tested and analyzed by different combination of parameters.The research concentrates on primary actuating properties of NiTi wires, such as phase transformation process, recovery strain in free condition, recovery stress at different restrained strains(2.14%, 2.87% and 3.6%) and stress temperature factors at different restrained stresses (50 MPa,75 MPa and 100 MPa ), which are mainly affected by temperature and applied stress. Experimental results are very useful to monitor the actuating behaviors and to design actuators of NiTi SMA in smart materials and structures.