Theoretical Analysis of Strain Concentration for Various Shapes of Distortion at Weld in a Pressure Vessel

Abstract

If some initial imperfections exist in the connection of structural members, a large strain concentration is induced by external loading. A large pressure vessel built by press bending and welding of steel plates occasionally creates initial distortion at the welded joint. The initial distortion often causes a reduction of the fatigue strength of the joint, owing to a considerable strain concentration. For rational quality assurance of the pressure vessels, a quantitative determination of relation between the initial distortion and the strain occurring at the joint is very important in all stages of the design, manufacture and maintenance of the pressure vessels. In the present paper, the authors theoretically discuss the influence of the shape of distortion on the strain concentration. The general formulae of strain calculation which are applicable to the arbitrary shape of distortion are obtained, and relation between the difference in the shape of distortion and the amount of strain concentration is graphically indicated.