Elucidation of Fatigue Fracture Mechanism on Glass-Fiber-Reinforced-Plastics

In this study, it was elucidated that the fatigue failure mechanism of glass-fiber reinforced plastics (GFRP) with different fiber orientations, and the relationship between the fiber orientation and the failure mechanism by using a simple unidirectional fiber orientation. Fatigue tests exhibited that GFRP, whose glass fiber oriented parallel to the load direction showed high fatigue strength. Furthermore, as a result of observing the fatigue fracture, in the case of GFRP containing fibers oriented parallel to the loading direction, fatigue cracks occur at the fiber edges, propagated through between the glass fibers and the matrix. After that, the fatigue crack propagation rate gradually decreases, the fatigue crack growth stopped, and finally, GFRP material was statically fractured. Therefore, this suggests that the increase in fiber length of fibers oriented parallel to the loading direction extends the fatigue crack propagation life, leading to an increase in total fatigue life.