Flexural fatigue behavior of 2D cross-ply carbon/carbon composites at room temperature

The primary goal of this research was to study the flexural fatigue behavior and enhancement of residual strength in 2D cross-ply carbon-fiber-reinforced carbon (C/C) composites. Flexural fatigue behavior was simultaneously examined under two stress levels (70% and 65%) by electrical resistance change (ERC) method. Residual strength and fracture behavior of C/C composites were investigated as well. The results show that shapes of electrical resistance change rate-fatigue cycle curves could reflect applied stress levels and damage types during cyclic bending load. The enhancement of residual strength only occurs at a stress level lower than the fatigue limit, and the property of enhancement decreases with the increase of fatigue cycles. In addition, three-point bending fracture in both unfatigued and fatigued specimens is of delamination mode and cyclic loading cannot enhance both bending strength and plasticity at the same time.