Fatigue damage evolution in unidirectional glass/epoxy composites under a cyclic load

The initiation and progression of fiber damage in on-axis UD glass/epoxy materials under fatigue loading conditions were studied. Uniaxial tension–tension fatigue tests at different load levels were carried out to monitor the fiber damage evolution through the fatigue lifetime. The damage evolution was quantified by initial fiber breaks, the evolution of fiber breaks, fragmentation and clustering progression. Through qualitative and quantitative analyses, it is shown how the fiber damage evolution depends on the number of cycles, the applied load level and the number of broken fibers during the first cycle.