Defects and Damage in Ceramic Matrix Composites (CMCs) - Impact on Material Performance

ABSTRACT: Innovative research and development leading to a dual-use advanced technology product is proposed. The product is a methodology and associated software for a damage-based non-linear deformation model to study the effect of manufacturing defects and service-induced damage in Ceramic Matrix Composites (CMCs). Once developed, the model would be used in conjunction with non-destructive evaluation (NDE) methods to predict the effect of defects and damage on structural properties, component life and residual strength. The primary focus is on 2D SiC/SiC and S200 CMCs for the gas turbine components. However the methodology would be applicable to a much broader class of CMCs and components for military and commercial applications. An innovative mechanistic (physics-based) modeling approach is proposed. The approach includes direct consideration of relevant defect and damage mechanisms. During Phase I models to describe the effect of defects such as matrix porosity and fiber fracture were developed and it was also demonstrated how the quantitative model inputs can be obtained using NDE techniques such as X-ray CT-scan. In Phase II we propose to continue the development and validation of the methodology in order to extend the applicability of the model to a variety of conditions relevant to aircraft operating conditions. NDE and laboratory test data needed to validate the model will be obtained under subcontract with Triton Systems, Inc. Pratt & Whitney. BENEFIT: Due to the proliferation in potential applications of ceramic matrix composites in military and commercial aerospace engines and in industrial gas turbine industries, the proposed dual-use high technology product has an immediate and expanding market. In conjunction with NDE techniques the proposed product will benefit these programs by improving the process of evaluation of as-manufactured CMC parts to sufficiently meet desired structural properties and design goals. The proposed product will also be useful in in-service component inspection and evaluation to estimate residual properties. SAI will market the methodology, the software and technical expertise (services) to these and other industries.