Fracture analysis of full-thickness clad beam specimens

摘要

Finite-element analyses were performed on full-tnickness clad beam specimens to quantify fracture toguhness for shallow cracks in material for which metallurgical conditions are prototypic pf those found in reactor pressure vessels (RPVs). The beam specimens are fabricated from a section of an RPV wall (removed from a canceled nuclear plant) that includes weld, plate, and clad material with metallurgical factors potentially influencing fracture toughness for shallow cracks. A summary of the testing program is provided and the analyses of the test data are discussed, including comparisions of measured displacements with finite-element analysis results, applications of toughness estimation techniques, and interpretations of constraint conditions impled by stress-based constraint methodologies. Fracture toughness estimates were obtained from displacement data using finite-element techniques and estimation schemes were obtained from displacement data using finite-element techniques and estimation schemes based on the tau -factor method. The J-Q methodology was used to assess crack-tip stress triaxiality in the clad beam specimens. The shallow-crack clad beam specimens showed a significant loss of constraint similar to that of other s hallow-crack single-edge notch bend specimens. THe stress-based Dodds-Anderson scaling model was also utilized to analyze constraint conditions in the clad beam specimens and appears to be effective in adjusting the test data to account for loss of in-plane constrain for uniaxially tested beams.