FIBER-MATRIX DEBONDING EFFECTS ON CRACKING IN ALIGNED FIBER CERAMIC COMPOSITES

The micromechanical fracture analysis of fiber-reinforced ceramics usually requires explicit consideration of sliding at the fiber-matrix interface that is resisted by frictional shear stress. But an interfacial debonding resistance may have to be overcome before frictional sliding can occur. This paper presents an approximate calculation of the stresses needed to initiate and propagate fiber-matrix debonding in the vicinity of a matrix crack. The results are used to define the parameters of a crack-bridging model that serves to determine the effects of debonding and initial stress on the matrix cracking stress of an aligned fiber composite, as well as their effects on overall composite toughness.