Prediction of flange debonding in composite stiffened panels using an analytical crack tip element-based methodology

Fracture mechanics-based predictive methodologies are commonly employed to estimate onset of interlaminar damage growth in composite structures. Full implementation of interlaminar fracture mechanics in design requires the continuing development of codes to calculate energy release rates and advancements in delamination growth criteria under mixed mode conditions. In this research, an analytical crack tip element (CTE) methodology was evaluated and applied to predict skin-to-stiffener separation, which is a typical failure mode in aerospace structures. The methodology was correlated against empirical data obtained from structural testing of a single blade stiffened panel with an embedded artificial debond. Failure initiation occurred at the location predicted by the CTE and the predicted load for initiation agreed with the average of a set of experimental results.