Elastic T-stress and I-II mixed mode stress intensity factors for a through-wall crack in an inner-pressured pipe

Elastic T-stress and stress intensity factor (SIF) solutions for through-wall-cracked pipes under internal pressures have been investigated by three-dimensional (3D) finite element (FE) calculations. The distribution of normalized SIFs (mode I KI and mode II KII) and T-stresses along the crack front for different crack lengths, crack orientations, thickness ratios and Poisson's ratios has been obtained in detail. Our FE results show that the T-stresses increase with increasing Poisson's ratio and crack angle, respectively. The normalized KI increases while KII decreases with increasing Poisson's ratio, respectively. The normalized KI decreases with increasing crack angle, while KII increases with increasing crack angle from 0° to 45° and then decreases from 45° to 90°. Finally, the empirical formulae of the three-parameter KI, KII and T-stress have been derived by fitting present FE results with the least-squares method for the convenience of engineering applications.