Transverse bending fatigue behaviors and failure mechanisms of 3D five-directional braided composites at different temperatures

This paper presents transverse bending fatigue behaviors and their failure mechanisms of 3D five-directional braided composites (3D5dBC) at room and elevated temperatures. 3D five-directional braided preform was braided and relevant composite was fabricated. In order to characterize relationship between fatigue strength and fatigue life of 3D5dBC, S-N and damage index curves were plotted. The deformation and energy consumption characteristics were analyzed via hysteresis loop curves. The results showed that the composite at room temperature was more fatigue resistant and the failure showed fatigue-induced stepped fracture mode, and fibers and matrix fracture finally resulted in failure of composite while interfacial debonding finally led to structure failure at elevated temperature.