Micromechanics of Stiffness Damage in Ceramic-Based Fiber-Reinforced Composites

The micromechanical analysis is performed to elucidate the stiffness reduction damage in the ceramic/ceramic composite whose matrix rupture strain is smaller than that of fibers. It is assumed that damage mechanism in the composite consists mainly of crack bridging fiber and interfacial sliding between the matrix and fibers. Energy release rate for a matrix crack and energy dissipation by the interfacial sliding was formulated by means of the inclusion modeling in micromechanics. Macroscopic stiffness at the given applied stress was derived in terms of the current lengths of matrix cracks. Finally, applicability of a parameter of damage accumulation in the material and its effect on macroscopic stiffness were discussed by the use of macroscopic stress-strain curves.