Fracture Analysis of Some Ceramics Under Mixed Mode Loading

Mixed mode fracture resistance was analyzed for some previously tested ceramics using a three-parameter fracture criterion called the generalized maximum tangential stress (GMTS) criterion. For using this fracture criterion, the size of a critical distance from the crack tip was required. Therefore, an analytical model was suggested for determining the size of critical distance in terms of mode I fracture toughness and the tensile strength of ceramics. For some ceramics with reported grain size, the size of critical distance was found to be approximately 100 times the average grain size. The experimental results obtained from the cracked Brazilian disk specimen and reported in the literature for sialon, mullite, SiC, glass, sintered carbide, porcelain, zirconia, and alumina could be estimated very well when the GMTS fracture criterion was used.