Cyclic Deformation and Fatigue Failure Mechanisms of Thermoplastic Polyurethane in High Cycle Fatigue

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 degrees.

Automated summary

The main purpose of this study is to analyze the fatigue failure of thermoplastic polyurethane (TPU) plate under tension-tension load control tests and investigate the change in hydrogen bond content. The results indicate that the S-N curve of TPU material exhibits a declining trend before reaching the fatigue limit, with energy consumption occurring during the cyclic creep process and undergoing three stages of hard segment and soft segment changes. The study also reveals that an increase in fatigue life leads to a decrease in hydrogen bond content and an increase in microphase separation, resulting in fatigue fracture.