Analysis of coupled ply damage and delamination failure processes in ceramic matrix composites

Damage and failure processes in two relatively complex ceramic matrix composite sub-elements are studied using both experiments and computational modeling. The sub-elements, representative of turbine blade-to-disk attachment region, are analyzed and tested under uniaxial loading at room temperature. The computational models consider – in a coupled way – both the nonlinear behavior of plies due to intra-laminar ply damage mechanism as well as the interlaminar delamination mechanism at the ply interfaces. Analyses and experiments indicate that delamination is the dominant failure mode and ply damage processes have a little effect on delamination initiation and growth. However, the ultimate failure of the sub-elements is due to ply damage mechanism, the evolution of which is strongly affected by the delamination process. The spatial locations of major delamination cracks and ply failure regions, as predicted by the models, are in good agreement with the experiments. In addition, a reasonable quantitative agreement between analyses results and experimental data is observed.