Characterizing the crack initiation load in circumferentially through-wall cracked elbows under bending load.

Ductile fracture assessments of circumferentially through-wall cracked elbows, based on the elastic–plastic J-integral concept, are discussed with particular interest in its ability and accuracy to predict experimental results corresponding to the initiation of stable crack growth. 3D non-linear finite element analysis is backed up with experimental results to determine the crack initiation load. Non-linear finite element analyses were performed considering both material and geometrical non-linearity using the advanced fracture analysis code WARP3D. Numerical analyses have been carried out to understand the role of crack tip constraint in standard specimens and the elbow component. An attempt has been made to obtain a unique multiaxiality quotient (q) for evaluation of the level of constraint. The work provides benchmark data to assist in the engineering treatment of cracked piping elbows