Experimental Investigation on the Fatigue Behavior of Glass Fiber-Reinforced Epoxy Composites Under Rotating Bending Loads

A glass fiber-reinforced epoxy (GFRE) composite, constituted by glass fibers in off-axis directions, i.e., [+/- 45 degrees](2S) was considered in this investigation for evaluating its static and fatigue behaviors. During the tensile test, GFRE composites exhibited nonlinear behavior, and subsequently reaching the ultimate point, test specimens rapidly failed owing to fiber failure. Fatigue tests were conducted under completely reversed rotating bending loads. The fatigue degradation model suggested by Hwang and Han was adopted to illustrate the effect of five different stress levels and test frequency (10 Hz) on the fatigue life of GFRE composites. From the obtained results, it was evident that the fatigue degradation model suggested by Hwang and Han shows good agreement with experimental results as compared to the S-N curve and Basquin's approaches. From SEM results, matrix cracking and fiber pullout were observed at lower stress levels, whereas under higher stress levels propagation of cracks in the longitudinal direction was majorly responsible for catastrophic failure of fibers.