镍钛微管拉扭实验装置的研制

Development of a combined tension-torsion testing machine for NiTi shape memory alloy microtubing

研制形状记忆合金微管专用的拉扭实验装置.根据形状记忆合金在应力作用下会发生马氏体相变、具有多尺度效应的力学特性,提供多种高精度拉扭复合加载路径,基于单个弹性元件实现正-剪应力测量,基于数字图像处理实现非接触、直接、同步及全场的正-剪应变测量,设定适合的照明光路支持试件表面形貌演化的拍摄.利用研制的装置对形状记忆合金微管进行系统的准静态拉扭实验,发现变形失稳现象,这可支持此类材料的本构关系研究.

A special combined tension-torsion testing machine has been developed for the shape memory alloy microtube which is becoming more and more widely used. Shape memory alloy may be subjected to martensitic phase transition under stress. There is multi-scale effect in its mechanical behavior. Accordingly, the testing ma- chine offers a series of combined tension-torsion loading paths with high-precision control, achieves normal and shear stress measurement by a single elastic component, achieves non-contact, direct, synchronized, and full- field normal and shear strain measurement based on digital image processing, and provides optimized lighting for photographing of the morphology evolution of specimen surface. By this machine, we first complete systematic quasistatic combined tension-torsion tests on shape memory alloy microtube and find some new phenomena of de- formation instability. It is valuable for the research on the constitutive relation of this kind of material.