T-stress for the double-edge cracked Brazilian disc under compression

Abstract

As the nonsingular term in the Williams series solution of the stress field at the crack tip, T-stress has a great influence on the crack propagation behavior. Under the loading condition for pure mode II fracture, negative T-stress (compressive T-stress) reduces the deflection angle for crack initiation and promotes the self-similar propagation of crack; while positive T-stress increases the crack deflection angle, and the crack kinks into tensile wing crack. The closed-form solution of the T-stress for the double-edge cracked Brazilian disc (DCBD) under compression is obtained by the weight function method. The closed-form solution in series form has a good convergence. The normalized T-stresses are calculated for different conditions, then the effects of distribution form, loading angle, contact angle, and relative crack length on T-stresses are analyzed. The results show that the effect of contact angle γ on T-stress should be considered when the loading angle θ and the relative crack length α are both small or great; while the effect of distribution form on T-stress cannot be ignored if and only if θ and α are small. The T-stress in the DCBD specimen is always negative when θ ≤ 20° and α ≥ 0.4. This is advantageous for the realization of true mode II fracture.