In‐Plane and Out‐of‐Plane Notch Tip Constraint in Predicting Notch Failure Assessment Curves

The paper focuses on a modified notch failure assessment diagram taking into account nonsingular Т хх ‐ and Т zz ‐stresses as in‐plane and out‐of‐plane constraint parameters in the fracture process zone. A local criterion of failure based on a maximum average tangential stress has been proposed to characterize notch failure assessment (NFA) curves. It is assumed that this average stress in the fracture process zone is equal to the local strength, which can be calculated. The Huber–Mises plasticity criterion including Т хх ‐ and Т zz ‐stresses is applied to estimate the local strength. It was observed the significant effect of out‐of‐plane notch tip constraints on NFA curves of flat plates under tension. The proposed notch failure assessment diagram taking into account the integrated effects of in‐plane and out‐of‐plane constraints is very relevant for structural integrity assessment of thick‐walled high‐pressure vessels and pipelines.