Estimation of SCC Crack Growth Behavior under Weld Residual Stress in the Bottom of a Reactor Pressure Vessel by Finite Element Analysis

摘要

Crack growth behavior intended for stress corrosion cracking under residual stress was estimated by repeatedly calculated 3-dimensional finite element analysis. The analytical estimation enables consideration of complicated stress distributions, such as weld residual stress, and expression of arbitrary crack shapes. Estimated weld residual stress for non-cracked components was distributed on the crack surface on the basis of superposition principle in order to calculate stress intensity factors. Specifically, the user subroutine DLOAD to specify a non-uniformly distribution load in ABAQUS was applied in the finite element analysis. Arbitrary crack shapes due to the crack propagation were expressed by applying the sub-modeling. The sub-modeling facilitated automatic modeling of cracked components. The estimation results intended for a SCC crack in the bottom of the reactor pressure vessel expressed the complicated crack growth shape along the weld metal. Moreover, crack growth behavior was estimated using the influence function method. The influence function method assumes arbitrary stress distribution and semi-elliptical crack shapes. Applicability of the influence function method was confirmed by comparisons with FEA results.