Prediction of initiation mechanism of three-dimensional penetrating single crack

In this paper, a novel calculating method for the three-dimensional stress intensity factor (SIF) was put out. By using the finite element approach, it was possible to compute the Mode I, Mode II, and Mode III SIF under the impact of a single factor (height, width, thickness, crack length, and inclination angle) and derive its variation rule. The SIF was computed by using the uniform design method, which also yielded the fitting formula that could determine the fracture at any geometric position on any plate. Then, a new three-dimensional penetrating crack fracture criterion was established to forecast both Mode I, Mode II, and Mode III initiation parameters of three-dimensional penetrating oblique crack. Uniaxial compression tests were done in order to validate the forecasted outcomes, including the crack initiation angle and load. The results demonstrate that the normalized K_I always decreases with z/t (the crack front spacing), while the normalized K_II and K_III increase first and then decrease. K_I and K_III increase with the crack length 2a, while K_II decreases first and then increases with the crack length. K_I and K_II both increase with the plate height. K_I rises with the crack inclination angle, while K_II and K_III initially raise and then lower. Along with the crack inclination angle, the crack initiation angle decreases, and the crack initiation stress rises. All of fracture mechanisms are Mode I.