This study investigated the process of the Lüders band formation and propagation within geometrically graded plate samples of a pseudoelastic NiTi during the stress-induced martensitic transformation by means of digital image correlation full-field strain measurement. The geometrically graded plate samples had parabolic width profiles in concave and convex forms along the length. Such sample geometries created a situation of progressively increasing applied load and a continuous variation of the sample width during the process of the stress-induced transformation. The size (along the sample length direction) of the Lüders band front transition zone was found to remain unchanged with variation of the sample width during the process, but the local strain rate across the transition zone was varied. The transition zone of the martensite Lüders band during the forward transformation was wider than that of the austenite Lüders band on the reverse transformation, and the local strain rate was lower than that of the latter.

本研究通过数字图像相关全场应变测量，研究了在应力诱导马氏体转变过程中伪弹性 NiTi 的几何梯度板样品中 Lüders 带的形成和传播过程。几何渐变板样品沿长度具有凹凸形式的抛物线宽度分布。这种样品几何形状造成了在应力诱导转变过程中逐渐增加施加载荷和样品宽度连续变化的情况。发现 Lüders 能带前沿过渡区的尺寸（沿样品长度方向）在该过程中随着样品宽度的变化而保持不变，但整个过渡区的局部应变率发生变化。