Theoretic Study And Experimental Verification Of Brittle Fracture Criterion For V-notches

Based on the basic equations of the elasticity plane problem, displacement fields and singular stress fields near the V-notch tip under mixed-mode of I and II are obtained for homogeneous materials by a new definition of the stress intensity factors.According to the strain energy density factor criterion under mixed-mode of I and II, the distortional strain energy density factor criterion and dilatational strain energy density factor criterion are given. The twin shear stress criterion is applied to the V-notch problem under mixed-mode of I and II. Systematic study is done for the strain energy density factor criterion, distortional strain energy density factor criterion, dilatational strain energy density factor criterion, circumferential tensile stress criterion, energy release rate criterion and twin shear stress criterion. They can be perfectly applied in engineering, because they are described only by two elementary parameters of the material: the tensile strength oC and the plane strain crack toughness Km..In order to verify these criterions, tensile experiments are carried out for many kinds of samples made out of plexiglas with a planar V-notch under mixed-mode of I and II. The directions of crack orientation and the critical loads predicted by the above criterions coincide with the experiment results.