Implication of as Manufactured Delaminations on CMC the Life of Ceramic Matrix Composites

The goal of the testing is to develop and life prediction theories which describe the structural re-sponse in CMCs with delaminations emanating from manufacturing imperfections. Much work have been done studying the effects of defects in CMCs particularly in the area of porosity, but no one has clearly explained the failure mechanisms ovserved in advanced CMC jet engine after burner flaps and seals. Analysis and physical evidence indicates that the combined thermo-structural and acoustic loadings combined with CMC thermal ageing/oxidation cause It is believed that the combined thermo-structural and acoustic loadings combined with thermal ageing cause the delaminations to spread across the CMC resulting in surface ply loss. The objective of the proposed effort will be to execute a research program to develop the appropriate representative S200 CMC material samples with delaminations of various sizes in test specimens and test types, and to demonstrate through tests, mathematical composite materials analysis, fracture based delamination growth modeling and finite element modeling the ability to predict test specimen structural delamination growth rate as a function of time, temperature and stress with and with-out production reportable delaminations through pre and post-test analysis predictions. BENEFIT: Several Air Force programs for ceramics matrix composites (CMCs) are targeted for use in ad-vanced jet engines. Examples are the Integrated High Performance Turbine Engine Technology (IHPTET) initiative, the versatile affordable advanced turbine engines (VAATE) initiative, Joint Strike Fighter (JSF) etc. This research will help prime engine contractor like Pratt & Whitney, Rolls Royce and General Electric.