Predictive Damage Model

ABSTRACT:The Physical Sciences Inc. (PSI) and ATA Engineering Inc. (ATA) team will develop and verify a model to predict damage created in ceramic matrix composites (CMC) as a result of machining processes. The model will enable the prediction of the useful life of a CMC component as a result of microcracking, fiber bundle rupture, delamination, and damage to the fiber/matrix interface coating in a silicon carbide reinforced silicon carbide (SiC/SiC) composites. During the Phase I program the PSI/ATA team will develop a model to predict the damage imparted to SiC/SiC materials as a result of contact milling. Initial model predictions will be compared to the existing database of mechanical test data. The model will be used to make predictions about material damage as a function of the feed, speed and tool engagement of a fluted endmill. The model predictions will be verified by performing cyclic fatigue testing on test specimens that are machined using extreme conditions simulated by the model. During Phase II the model will be expanded to include arbitrary fiber architectures, laser machining and waterjet cutting to provide a complete tool for design engineers to model the manufacturing process for SiC/SiC components.BENEFIT:The successful development of a predictive damage model for machining processes will enable ceramic composite components to be cost effectively manufactured with higher reliability than is currently possible. Increasing the use of ceramic composites in propulsion and aeroshell applications will lead to improved fuel efficiency, higher reliability and an expansion of the performance envelope of Air Force vehicle systems. Many of these benefits will transition into commercial propulsion systems and improve the competitiveness of American propulsion system manufacturers in commercial markets.