Bending Fatigue Analysis of Various Polymer Films by Real-Time Monitoring of the Radius of Curvature and Heat Generation

Understanding the fatigue behavior of polymer films undercyclicbending is essential to the design of suitable substrates for flexibleelectronics. However, bending fatigue remains unclear due to the lackof comprehensive and quantitative investigations across various polymerfilms. Herein, we quantitatively investigate the bending fatigue behaviorof various polymer films with a newly developed multifunctional bendingfatigue tester that can precisely evaluate the radius of curvatureand heat generation during the fatigue process. Measuring the radiusof curvature reveals that the polymer structures affect the surfacebending strain and fracture modes, which are critical factors in fatiguelife. Furthermore, heat is accumulated in polymer films under high-ratecyclic bending, leading to thermal degradation and a shortening ofthe fatigue life. These investigations provide us with an effectivevariable for machine learning and improve the prediction accuracyof the fatigue life. The resultant perspectives enable us to comprehendthe fatigue behavior and fatigue life of polymer films subjected tocyclic bending, facilitating the development of flexible electronicdevices and soft robots.

Automated summary

In this study, the bending fatigue behavior of various polymer films was quantitatively investigated using a newly developed multifunctional bending fatigue tester. It was found that the polymer structures affected the surface bending strain and fracture modes, while heat accumulation under high-rate cyclic bending led to thermal degradation and shortening of the fatigue life. These findings provide valuable insights into the fatigue behavior and life of polymer films, facilitating the development of flexible electronic devices and soft robots.