Prediction of delamination growth in laminated structures

An engineering methodology is proposed for the prediction of delamination growth in laminated composite structure. This methodology builds on previous successes while addressing some deficiencies in current approaches; primarily, the proposed methodology describes a means through which computational and experimental requirements may be reduced. As its major components, the methodology includes a procedure for eliminating the (analytically predicted) oscillatory nature of the stress singularity between plies at dissimilar orientations, a computationally efficient crack tip element analysis for determining mixed-mode energy release rates, and experimental assessment of 'minimum' toughness curves, at a given mode ratio, as a function of relative interfacial ply orientation and the number of loading cycles. The utility of the methodology is demonstrated through two examples: one monotonic and one fatigue loaded application. In both cases, good correlation between experimental results and theoretical predictions are obtained. A number of currently unresolved issues are also discussed.