Wang Shuo, Tang Sen, He Chao, Wang Qingyuan
School of Mechanical Engineering, Chengdu University, Chengdu 610106, China.
Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610207, China.
Polymers (Basel). 2023 Feb 11;15(4):899. doi: 10.3390/polym15040899.
In this study, the main purpose is to analyze the fatigue failure of thermoplastic polyurethane (TPU) plate under tension-tension load control tests (frequency = 5 Hz, stress ratio = 0.1) and consider the change in hydrogen bond content. The results show that the S-N curve of TPU material shows a downward trend before reaching the fatigue limit (10.25 MPa), and the energy is continuously consumed during the cyclic creep process and undergoes three stages of the hard segment and the soft segment changes. The infrared spectrum study shows that the increase in fatigue life will lead to more physical crosslinking, resulting in the reduction of hydrogen bond content, and the increase in microphase separation, leading to the occurrence of fatigue fracture. In addition, the scanning electron microscope and three-dimensional confocal analysis showed that the crack originated from the aggregation of micropores on the surface of the material and was accompanied by the slip of the molecular chain, the crack propagation direction was at an angle of about 45°.
在本研究中，主要目的是分析热塑性聚氨酯（TPU）板在拉-拉载荷控制试验（频率=5Hz，应力比=0.1）下的疲劳失效，并考虑氢键含量的变化。结果表明，TPU材料的S-N曲线在达到疲劳极限（10.25MPa）之前呈下降趋势，在循环蠕变过程中能量不断消耗，并经历硬段和软段变化的三个阶段。红外光谱研究表明，疲劳寿命的增加会导致更多的物理交联，从而使氢键含量降低，微相分离增加，导致疲劳断裂的发生。此外，扫描电子显微镜和三维共聚焦分析表明，裂纹起源于材料表面微孔的聚集，并伴随着分子链的滑移，裂纹扩展方向约为45°角。
