Effect of fiber bridging on the fatigue crack propagation in carbon fiber-reinforced aluminum laminates

A superior crack propagation resistance was observed on various carbon fiber-reinforced aluminum laminates (CARALL) under tension-tension fatigue. It might be attributed to the restraint on the crack opening imposed by intact fibers in the crack wake. These fibers bridging the crack could reduce the effective stress intensity factor actually experienced by the crack tip. Based on the measurement of crack length and delamination size, the effective stress intensity range, ΔKeff, of fatigue-damaged CARALL laminate was calculated by using a simplified analytical model. It was shown that the fatigue crack propagation rate in CARALL could be expressed as a unique function of the calculated ΔKeff, which agree well with the Paris equation for the unreinforced aluminum alloy. This result confirmed the applicability of this simplified analytical model in CARALL laminates.