Defects and Damage in Ceramic Matrix Composites (CMCs) Implications for Component Life Prediction (MSC P2138)

A physics-based life prediction methodology for ceramic matrix composites (CMCs) which can account for the component operating environment (thermal, structural, chemical) in the context of realistic defects and damage has not been sufficiently demonstrated. The innovation offered by this proposal is a unique computationally efficient methodology for predicting both the overall effective constitutive relation and damage evolution equations for materials with very complex micro-structures. Local failure modes (cracks) are treated by formulating an effective thermodynamic and dissipation potential in terms of these discrete damage. Under this program, a Discrete Damage Space Homogenization Method (DDSSHM) will be implemented to predict the deformation, damage initiation and growth of micro-cracks, and a methodology will be outlined for total life prediction of CMCs under expected service environmental and thermo-mechanical loading. The DDSHM represents a true physics-based approach as matrix cracks are treated by formulating an effective thermodynamic and dissipation potential in a theoretical framework that differs from the widely cited phenomenological continuum damage mechanics method. BENEFIT: The proposed research will result in the implementation a mathematically sound methodology for life prediction of CMC materials, accounting for component operating environments and realistic defects and damage. These constitutive relations will e integrated into a commercial finite element software program, ABAQUS, and conducted sufficient global structural analysis to show that this theory can be practically implemented for"real"structures. A significant opportunity/benefit also exists for data transfer between the CMH-17 CMC Working Group and this program to enable development of life prediction modeling guidelines.