Solution of stress intensity factor of surface cracked geometry with clamped ends

Determination of the stress intensity factor (SIF) of surface cracked geometry with clamped ends is necessary for crack growth analysis in laboratory. Based on the feature of the clamped ends, the clamped condition was simplified as a combined uniform tension stress and bending moment act with the rotation angles of the specimen ends retained to be zero. The elastic potential energy of the equivalent model was derived based on Newman-Raju expression of SIF for surface crack under free uniform tension and bending moment, and then the function relationship between the uniform tension stress and the bending moment was deduced using Castigliano's first theorem. By superposition, the SIF expression of the equivalent model was given. To verify the validity of the expression, SIF solutions of some representative surface cracked geometry with clamped ends were obtained by Abaqus. Comparisons indicate that the expression is accurate enough. In addition, the relationship of crack shape and length-to-thickness ratio to the modifying factor for clamped ends was analyzed.