Crack shape developments for LBB applications

The flaw shape during sub-critical crack propagation (fatigue or stress corrosion) is important in order to estimate the crack opening area and leak rate at breakthrough and for the leaking crack. The ability to detect this leak rate is one of the cornerstones in the leak before break philosophy. In this study, the crack shape development is analysed and predicted using modern FEM techniques. The predictions are benchmarked against available fatigue experiments. Recommendations are given for crack shapes for both surface cracks and through-wall cracks in pipes and plates, and for sub-critical crack propagation as well as ductile tearing loading.