Residual stress analysis by simplified inherent strain at welded pipe junctures in a pressure vessel

We present a new and simplified method of estimating residual stress in wel ded structures by using inherent strain. The method makes use of elastic an alysis by means of the finite element method and is used to calculate the r esidual stress in complicated three-dimensional structures efficiently. The inherent strain distribution in a welded joint of a small-diameter pipe pe netrating a pressure vessel was assumed to be a simple distribution, and th e residual stress was calculated. Inherent strain distributions were inferr ed from those of welded joints with simple shapes. The estimated residual s tress using these inferred inherent strains agrees well with the measuremen ts of a mock-up specimen. The proposed method is a simple way to estimate w elding residual stress in three-dimensional structures of complicated shape s.