The Stresses in Fusion Joints

Abstract

Modern use of fusion joints instead of riveted or bolted connexions has produced a variety of new forms which offer numerous fields of inquiry covering a great range of problems. One set of problems relates to stress distribution directed more especially to the determination of the maximum stresses in fusion joints. This is almost entirely an experimental matter, since nearly all such joints have discontinuities imposed by practical necessities which render them insoluble by theoretical analysis, while little or no help can be gained from our existing knowledge and long experience of riveted and bolted joints on account of their essentially different nature. The present inquiry deals with problems of plane stress distribution in which models are used for measuring the stress at any point required by photo-elastic means, and in the first instance some typical butt welds of an unsymmetrical type are analysed experimentally. Other ways of connecting plates in line are then considered in which a joint is made by a lenticular section of weld metal on one side and a cover plate on the other, the ends of the latter being joined to the main plates by triangular sections of fusion metal. When the gap between the two main plates is sufficient the lenticular section of metal may be replaced by a pair of triangular fillets binding the inner ends of the plates to the cover strap, and this form is also dealt with. The effects of triangular fillets of lesser height than the butt straps and of corresponding fillets of curved quadrantal form are also examined with reference to a double butt strap joint. The paper concludes with a brief summary of the main results afforded by the experimental analysis.