Elevated-Temperature Life Limiting Behavior of Hi-Nicalon SiC/SiC Ceramic Matrix Composite in Interlaminar Shear
NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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Assessments of life limiting behavior of a gas-turbine grade, melt-infiltrated Hi-Nicalon SiC continuous fiber-reinforced SiC ceramic matrix composite CMC were made in interlaminar shear using both stress rupture and constant stress-rate testing at 131 60C in air. The composite exhibited appreciable life limiting behavior with a life susceptibility parameter of nsub s22-24, estimated based on a proposed phenomenological life prediction model together with the experimental data. The phenomenological life model was in good agreement in prediction between the stress rupture and the constants stress-rate data, validating its appropriateness in describing the life limiting phenomenon of the CMC coupons subjected to interlaminar shear. Despite some limitations in material availability, time to failure and shear strength data exhibited a statistical relation, typically observed in Mode I loading for many isotropic brittle solids. The results of this work also indicated that the governing mechanisms associated with failure in interlaminar shear remained almost unchanged, regardless of the type of loading configurations, either - in stress rupture or in constant stress rate. This additionally indicates that simplistic constant shear stress-rate testing can be used as a possible means of life prediction test methodology for CMCs even in interlaminar shear at elevated temperatures when relatively short lifetimes are expected.
- Laminates and Composite Materials