Failure mechanisms and damage evolution in crossply ceramic-matrix composites (Q675364)

Failure mechanisms were studied under the microscope in a crossply silicon carbide/glass-ceramic composite under axial tensile loading. Failure initiation takes place in the \(90^\circ\) layer. It takes the form of radial matrix cracks around the fibers, followed by interfacial cracks, which in turn coalesce into transverse macrocracks. These transverse macrocracks in the \(90^\circ\) layer reach a characteristic saturation crack density with a minimum crack spacing of the order of the layer thickness. This is finally followed by delamination and additional cracking in the \(90^\circ\) layer prior to ultimate failure. Various failure mechanisms and their interactions are discussed and compared with predictions of experimental and analytical studies of unidirectional and crossply composites.