Failure prediction of graphite/epoxy laminates with induced intermittent load surge during fatigue Original Research Article

An analytical model, supported by numerical simulations, which describes the behavior of the energy release rate of composite laminates subjected to fatigue overloads is presented. The model establishes that accumulation of damage due to intermittent surge in applied load reduces the energy release rate, G, of the material. The effect of constant amplitude, regularly applied overloads on the energy release rate of [0/90]n graphite/epoxy composites appears to diminish as the structural integrity reduces over time, suggesting the effects of overloads is more severe during the initiation of delamination growth. The results obtained in this study have no restrictive assumptions regarding the specimen or the delamination thickness, T and h, respectively, and are presented over varying mode-mixity and h/T ratios. Simulations are correlated and compared with data from performed experiments confirming the model’s functionality and predictive capability. Results of this investigation shed light on the nature and extent of damage accumulation during spectral fatigue.