Constraint analysis of thickness effects on fracture resistance behavior of clamped single-edge notch tension specimen

The correlation between the out-of-plane stress and the in-plane stress is established based on the bending modified J-Q theory and the out-of-plane constraint parameter TZ. Accordingly, an improved J-QZ-M constraint theory is developed to characterize the crack-tip fields by taking into account opening- and bending-dominated deformations in the ligament of the clamped single edge notch tension (SE(T)) specimens. Three-dimensional elastic-plastic finite element analyses (FEA) with a wide range of in-plane and out-of-plane constraints are performed to validate the proposed approach. It is found that the proposed J-QZ-M constraint theory can effectively quantify the crack-tip fields of SE(T) specimens, and the constraint parameter QZ exhibits approximately load- and distance-independence until large scale yielding (LSY).