Probabilistic Analysis of Composite Structure Ultimate Strength

A practical system reliability-based technique is proposed for probabilistic estimation of the ultimate strength of composite structures. Important component failure sequences to system failure are identified using a fast branch and bound search procedure. Ply-level failure modes such as matrix cracking, fiber failure, and delamination are considered, and system degradation due to progressive failure and load shedding is modeled. The system failure probability is computed using the dominant failure sequences. The correlation between failure sequences is exploited to achieve computational efficiency. The variation of system failure probability with accumulating damage and load shedding is investigated to define the critical damage accumulation. The proposed methodology is applied to the analysis of a composite wing structure.