Li Jian, Kan Qianhua, Chen Kaijuan, Liang Zhihong, Kang Guozheng
State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China.
Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China.
Polymers (Basel). 2019 Jun 4;11(6):982. doi: 10.3390/polym11060982.
In situ monotonic tensile experiments of thermo-induced shape memory polyurethane (SMPU) at different loading rates were carried out by the digital image correlation (DIC) method and infrared camera FLIR-A655sc in natural convection (NC) and forced convection (FC) conditions, respectively. The multiform strain localization of SMPU was observed by the DIC method, and the influence of thermo-mechanical coupling on the strain localization was analyzed by using the FLIR to measure the temperature field caused by the internal heat generation. The experimental results show that the strain localization mode strongly depends on the strain rate and convection condition, and the strain localization mode can be transformed by changing the convection condition from NC to FC. The competition mechanism between the strain hardening induced by the increasing loading rate and strain softening induced by the internal heat generation is indicated, the transition modes of strain localization are clarified, and the influences of thermo-mechanical coupling on shape memory effect are discussed.
分别采用数字图像相关（DIC）方法和红外热像仪FLIR - A655sc，在自然对流（NC）和强制对流（FC）条件下，对热致形状记忆聚氨酯（SMPU）进行了不同加载速率下的原位单调拉伸试验。通过DIC方法观察了SMPU的多种形式应变局部化，并利用FLIR测量内热产生引起的温度场，分析了热 - 机械耦合对应变局部化的影响。实验结果表明，应变局部化模式强烈依赖于应变率和对流条件，并且通过将对流条件从NC改变为FC可以转变应变局部化模式。指出了加载速率增加引起的应变硬化与内热产生引起的应变软化之间的竞争机制，阐明了应变局部化的转变模式，并讨论了热 - 机械耦合对形状记忆效应的影响。
