Fatigue delamination growth rates and thresholds of composite laminates under mixed mode loading

The effect of delamination resistance on fatigue crack growth behavior of composite laminates is studied. The strain energy release rate normalized to fatigue delamination resistance (Gcf) is proposed as a controlling parameter to evaluate the fatigue crack growth rates and thresholds. Compared to previously developed Gcf determination method, the compliance approach presented in this paper shows obvious advantages, such as no interruption to the fatigue crack growth and independence on the specimen dimensions. Based on this approach, the fatigue delamination growth rates and thresholds of carbon/bismaleimide composite laminates under mixed I/II mode loadings are determined experimentally.