Fracture Criterion for Alumina Ceramics Subjected to Triaxial Stresses

Triaxial stress tests of alumina ceramics were conducted by pure bending under hydrostatic pressure, and by internal pressurization of an open-end thin-walled tube under hydrostatic pressure. The fracture stresses plotted in the principal stress space did not conform to existing fracture criteria. So, for fracture of the material, the flaw model consisting of randomly oriented penny-shaped cracks was assumed. The fracture criterion obtained from a statistical viewpoint by taking account of flaw distributions could explain well the experimental results.