Tensile damage development in fiber-reinforced ceramic matrix composites

Abstract

The mechanisms that control damage development and tensile failure of cross-plied Nicalon-fiber-reinforced glass and glass ceramic matrix composites were investigated using an edge replication technique. Four different systems were studied to determine the effect of interfacial bond strength and residual stress on the failure process. Composites with weak interfacial bonds were more resistant to matrix microcracking. Residual stresses, due to fiber-matrix and ply-ply thermal expansion mismatch, were found to have a strong influence on the damage development process; initiation of transverse ply cracks was delayed to higher strains (greater than 0.1%) in systems with residual compressive stresses in the transverse plies. Crack spacing measurements showed a saturation crack density was achieved with increasing load in both the longitudinal and transverse of all four composites. The experimental findings were used to modify for ceramic matrix composites the Laws and Dvorak model of composite cracking. © 1994.