Two-parameter fracture prediction for cracked plates under bending

Abstract

In this work, the fracture prediction method based on two-parameter J-Ad* (J-integral and a new load-independent unified constraint parameter Ad*) with considering both in-plane and out-of-plane constraints has been investigated for semi-elliptical surface cracks in plates under bending. The crack initiation locations and fracture initiation loads for different crack sizes have been comparatively predicted and analyzed by using the two-parameter J-Ad* and the conventional single-parameter J-integral. The predicted results based on the two-parameter J-Ad* approach have been verified by finite element simulation based on the GTN (Gurson–Tvergaard–Needleman) micromechanics model. The results indicate that the two-parameter approach can provide more accurate predictions. The conventional single parameter approach can produce conservative (for shorter and shallower cracks) or non-conservative (for longer and deeper cracks) results. It is recommended that in the application of the two-parameter approach, for obtaining the best prediction accuracy, the two parameters should be calculated at the crack initiation location.