A method for analysis of residual welding stresses and deformations based on the inherent strain: A theoretical study of residual welding stresses and deformations (Report 1)

Abstract

A fundamental theory for the analysis of residual welding stresses and deformations based on the inherent strain distributed along the welded joint is presented. The first part of this paper deals with a general solution to a two-dimensional inherent stress problem which is a special case of the inherent stress theory presented by the author in a previous work. In the welded structures, the inherent strain is commonly created within the narrow strip-like region which encloses a welded joint. Therefore, the analysis of residual stress due to welding can be simplified using a model in which the inherent strain is assumed to be distributed on a line. In this case, the characteristics of the idealized inherent strain may be expressed by the intensity of the distribution. The concept of the inherent shrinkage of welded joint is introduced through the longitudinal and transverse components of this intensity of the inherent strain. The second part is concerned with the analogy between the two-dimensional inherent stress problem and the inherent deflection problem of a plate. A general solution to the inherent deflection of an elastic plate is directly obtained from this analogy by introducing the inherent curvature corresponding to the inherent strain. The inherent welding deformation is therefore defined as the combination of the inherent shrinkage and the inherent warping. In this paper, the inherent welding deformation is represented by six basic components, i.e. longitudinal shrinkage, transverse shrinkage, staggering; longitudinal warping, transverse warping and twisting. They are schematically illustrated in Fig. 7. In the last part, an example of the inherent strain distribution along a butt welded joint is presented. This was recalculated by the author from the theoretical results of thermo-elastoplastic analysis of transient welding stress carried out by Prof. I. Tsuji of Kyushu University. © 1970, JAPAN WELDING SOCIETY. All rights reserved.