Three-Dimensional J-Integral. An Investigation into Its Use for Post-Yield Fracture Safety Assessment

摘要

The applicability of the J-integral to the prediction of crack growth initiation in complex, three-dimensional structures was investigated. It is shown that the J-integral can be extended to plane curved cracks in three-dimensional bodies without any additional restrictions. Direct evaluation of integral expressions and a procedure known as the virtual crack extension technique are shown to yield identical results, but the virtual crack extension technique is recommended because it is easier to apply. A procedure for indirect validation of the initiation load predicted by a three-dimensional elastic-plastic finite element analysis and the specimen JIc values of a uniaxially loaded plate model with a quarter elliptical crack emanating from a central hole is presented. Although the J-concept can predict residual strength of cracked structures, manpower and computer costs are high.