Bending Fatigue And Fem Model Of Several High-Performance Fibers

Soft materials inevitably produced fatigue failure and performance failure by external repeated actions in the use process. Fiber material especially used in industry is often repeated bending effect. The bending fatigue life influence the product finally use characters, so the research of the fiber material fatigue properties is necessary. With regard to the traditional metal materials, there are many bending fatigue reports, but there is less research of the bending fatigue of the textile fiber. Scholars begin to pay more attention to the fiber of the bending fatigue. At home and abroad, there are many bending fatigue instruments, such as pulley bending fatigue instrument, three bending fatigue instrument and clock pendulum bending fatigue instrument, those bending fatigue instruments are not fixed point. Considering the deficiencies of these instruments, we used the self-made fiber fixed point bending fatigue instrument, which can realize flexible single fiber bended at fixed point.Firstly, the high performance fibers of Kevlar49. Twaron2000, Nomex and Spectra2000were tested using LLY-06single fiber tester, then tested by the point bending fatigue. It can be found that:(1)Under the same situation, the bending fatigue lifetime of the Kevlar49and Twaron2000were approximate, the Nomex liber was the worst, the Spectra2000fiber was far better than other test fibers.(2)Under the same bending angle, the initial pre-stress was larger, the fatigue life of fiber was smaller. Under the same initial pre-stress. the bending angle was bigger, the fatigue life of fiber was smaller. There were linear correlations between the logarithmic fatigue life of the fiber and the fiber pre-stress. There were linear correlations between the logarithmic fatigue life of the fiber and the bending angle.(3) Kevlar49fiber bending fatigue failure head ends were serious fibrillar splitting, and belonged to the separation fracturing. Twaron2000also belonged to the separation fracturing. Spectra2000fiber generated plastic damage. Nomex mainly appeared tearing failure.The static problems of high performance fiber were analyzed by ABAQUS. and the maximum stress and the fiber material fatigue life curve (S-N curve) were obtained under the different parameters. Through the fatigue analysis software FE SAFE to predict the fatigue lives of fibers, and fiber materials lives were obtained in various parameters. Based on comparative experiments and finite element calculation results, we found both of the fiber bending fatigue life research had very good consistency. Through the error analysis, we found that when the stress was larger, the error was bigger.The experiment and calculation results in this dissertation could give direction for the high performance fiber application.