The Study of Fatigue Behavior of Glass Fiber Reinforced epoxy(GFRP) Composite Under Different Stress Levels

The aim of this study is to investigate the fatigue behavior of GFRP composite with biaxial fiber orientation [0,90] under different stress levels. First, the tensile test was performed and the UTS value was 420 MPa. Then, fatigue test was performed at 4 stress levels of 70, 50, 42 and 35% of UTS. Fatigue results had acceptable dispersion and the fitting curve on the data also matched well. Finally, the fatigue failure structures of 70 and 35% of UTS samples, using scanning electron microscopy (SEM) were evaluated. The results showed that in both 70 and 35% samples, the mechanism of pull out fibers was obsvered but its intensity was higher in 35% sample. Also in the 35% sample, significant distortion was observed which was absent in the 70% sample. On the other hand, the brittle failure of matrix was more pronounced in the 70% sample than in the 35% sample. This can be related to the increase of the matrix softness due to the application of cyclic load.