The Inherent Strain Method for Residual Stress Determination and Its Application to a Long Welded Joint

In this paper, we investigate a relatively new method for determining three-dimensional sub-surface residual stress (Ueda, 1975). This hybrid experimental/analytical method determines the source of residual stress by sectioning and strain measurement, and then uses it to deduce residual stress in the original body. When certain assumptions about the spatial distribution of the source of residual stress can be made, estimates of residual stress can be generated for locations which are remote from strain measurement points. We outline the method and then illustrate its application to measurement of residual stress in a long welded joint. First, background regarding the nature of residual stress and a formulation of the inherent strain approach to residual stress determination is discussed. Then, application of this method to a long continuously welded joint is described. A model problem is developed and solved by application of finite element analysis. Taking the finite element stress results as if they were experimental measurements, the inherent strain method is used to find residual stress. The accuracy of the method is then investigated by comparing the inherent strain and finite element solutions. Finally, the advantages and drawbacks of this relatively new method are discussed.