Fracture assessment procedure for structural components under cyclic and dynamic loading

A new fracture assessment method that includes 2 concepts is presented in this paper for structures subjected to large cyclic and dynamic loading. One is a reference temperature concept. The fracture toughness under cyclic and dynamic conditions is replaced by the static toughness without pre-strain at a reference temperature of T - Delta T-PD, where T and Delta T-PD are the service temperature and the temperature shift of the fracture toughness. Delta T-PD is related to the How stress elevation by pre-strain and dynamic loading. The other is a correction of CTOD (Crack Tip Opening Displacement) for constraint loss in structural components in large-scale yielding. The CTOD toughness correction is carried out with the equivalent CTOD ratio beta defined on the basis of the Weibull stress criterion. These 2 concepts are implemented in the Japanese Engineering Standard, WES 2808. The procedure for determining beta is standardized in the IST project in Japan, discussed below. For integrity assessments of pipelines with a high internal pressure, the effect of biaxial loading on beta is addressed by 3-dimensional FE analysis.