A Mixed-Mode Fracture Criterion for Brittle Materials

The inclined surface cracks are under the mixed mode I,II,III loading conditions. Direct tension experiments of brittle materials with surface crack have been carried out. The crack growth process, fracture pattern and the initiation angle of the surface crack were attained. In order to analyze the mixed-mode fracture criterion of the surface crack in brittle materials stress intensity factor of the crack front of the surface crack was calculated based on the FRANC3d firstly. And then the minimum strain energy density criterion, the maximum circumferential stress criterion and the revised maximum circumferential stress criterion were used to calculate the initiation angle. The revised maximum circumferential stress criterion proved to be fit for the attained experimental results.