Book Description

Recent research on crack-tip constraint on fracture, including the effect of in-plane biaxial stress fields, has led to a two-parameter elastic K-T and elasto-plastic J-Q approach to correlate fracture toughness. These approaches predict a significant influence of biaxial stress state on fracture toughness. In the case of reactor pressure vessels undergoing pressurized thermal shock (PTS), significant stresses induced parallel to the crack front (out-of-plane stresses) offer additional constraint at the crack-tip. In order to evaluate the effect of this out-of-plane stress field on fracture of reactor pressure vessel steels, a unique method for testing a cruciform-type double-edge notch, DEN(T), specimen loaded in biaxial tension was developed. Three-dimensional finite-element analyses were conducted to design the specimen configuration. Details of the experimental and analytical results and the significance of the crack-tip constraint, due to biaxial stress state involving out-of-plane stresses, on the fracture toughness in the transition region are presented.