Modelling and experimental investigation of geometrically graded NiTi shape memory alloys
Modelling and experimental investigation of geometrically graded NiTi shape memory alloys
复制标题
DOI：
10.1088/0964-1726/22/2/025030
复制
发表时间：
2013-02
影响因子：
4.1
通讯作者：
B. Shariat;Yinong Liu;G. Rio
中科院分区：
文献类型：
--
作者：
B. Shariat;Yinong Liu;G. Rio
为了改善NiTi形状记忆合金部件在应用中的致动可控性，期望为合金中的应力诱导马氏体相变产生宽的应力窗口。一种方法是创建在致动方向上具有几何梯度的功能梯度NiTi。该几何梯度导致结构中的转换载荷和位移梯度。本文报道了通过力学模型分析和实验，使用三种类型的样品几何形状的几何梯度NiTi的伪弹性行为的研究。得到了循环拉伸载荷作用下此类构件名义应力-应变变化的闭合解，并与实验数据进行了验证。几何梯度NiTi样品在应力诱导的马氏体相变中表现出独特的正应力梯度，并且应力梯度的斜率可以通过样品几何设计来调节。
To improve actuation controllability of a NiTi shape memory alloy component in applications, it is desirable to create a wide stress window for the stress-induced martensitic transformation in the alloy. One approach is to create functionally graded NiTi with a geometric gradient in the actuation direction. This geometric gradient leads to transformation load and displacement gradients in the structure. This paper reports a study of the pseudoelastic behaviour of geometrically graded NiTi by means of mechanical model analysis and experimentation using three types of sample geometry. Closed-form solutions are obtained for nominal stress–strain variation of such components under cyclic tensile loading and the predictions are validated with experimental data. The geometrically graded NiTi samples exhibit a distinctive positive stress gradient for the stress-induced martensitic transformation and the slope of the stress gradient can be adjusted by sample geometry design.