MODELING DAMAGE IN UNIDIRECTIONAL CERAMIC-MATRIX COMPOSITES

This paper extends the modified shear-lag model developed previously t o analyze the damage progression within a unidirectional fiber-reinfor ced ceramic-matrix composite subject to quasi-static lending. The dama ge mechanisms considered in this paper are matrix cracking, fiber/matr ix interfacial debonding, interfacial slip and fiber failure. Crack de nsity is determined analytically through the introduction of a 'critic al matrix strain energy'. A priori knowledge of the composite's 'propo rtional limit' yields a complete closed-form stress/strain solution. T he influence of the interfacial shear stress, the interfacial bond str ength and the composite proportional limit on the progression of matri x cracking and interfacial debonding are reported. The unloading behav ior, including stress/strain hysteresis, is also modeled in terms of i nterfacial frictional slip within debonded regions.