Is crack branching under shear loading caused by shear fracture? --A critical review on maximum circumferential stress theory

摘要

When a crack is subjected to shear force, crack branching usually occurs. Theoretical study shows that the crack branching under shear loading is caused by tensile stress, but not caused by shear fracture. The co-plane shear frac- ture could be obtained if compresive stress with given direction is applied to the specimen, subsequently, calculated shear fracture toughness, K_IIC, is larger than K_Ic. A prerequisite of possible occurrence of model II fracture was proposed. The study of shear fracture shows that the maximum circumferential stress theory considered its criterion as a parametric Equation of a curve in K_I, K_II plane is incorrect; the predicted ratio K_Iic/K_Ic=0.866 is incorrect too.