A 3-D ellipsoidal flaw model for brittle fracture in compression

Engineering materials are rarely free of ~aws[ Mode I cracking from pre!existing ~aws is the major cause of the brittle fracture in compression of materials such as concrete and rock[ A 2!D ellipsoidal ~aw model is used to show the signi_cant in~uence of ~aw geometry on crack initiation in uniform uniaxial\ biaxial and triaxial compression[ The model shows that the governing criterion for crack initiation may change from energy to stress with increasing crack size\ and that for voids of similar size a spherical void is the most critical shape for crack initiation[ The model thus provides a basis for a better understanding of both the phenomenon and the mechanism of brittle fracture in compression