Engineering Criticality Assessment of Flawed Bi-Metallic Girth Weld Joint

Nicola Bonora, Andrew Ruggero
Techdyn Engineering

Antonio Carlucci

The objective of the work is to establish, for a bi-metallic girth weld joint, up to which level of remote stress/strain is still conservative the use of the standard approach to perform an Engineering Criticality Assessment (ECA) considering the joint made of a single equivalent material. Several flaw types located at the interfaces between the joint materials were considered. Extensive finite element analysis was performed to derive the crack driving force using domain integral method. The possibility to use, with appropriate meshing, the CTOD as parameters to directly derive the J-integral in the numerical simulation is also demonstrated. The applicability of continuum damage mechanics models for crack propagation for high toughness-low yield materials is also shown. Computational results indicate that the use of a material curve, obtained as the lower bound of all joint materials curves, lead to conservative results.