On the use of linear-elastic local stresses to design load-carrying fillet-welded steel joints against static loading

Abstract

On th e u s e o f lin e ar-e las tic lo cal s tre s s e s to d e s ign lo a d -carryin g fille t-w e ld e d s te e l jo in ts again s t s tatic lo ad in g IN TROD U CTIONReviews both in the USA and Europe [1,2] indicate that in-service breakage of engineering structures and components costs around 4% of GNP in industrialised nations, the price which has to be paid becoming socially unacceptable whenever failures result in loss of human lives. In this complex scenario, one of the most difficult challenges faced by the metalworking sector is improving the in-service performance of structural assemblies by limiting not only the weight, but also the associated production, maintenance and energy costs.With regard to the technological issues involved in the manufacturing process, it is well-known that a challenging aspect of making high-performance structures and components is efficiently joining Please, cite this paper as: Ameri, A. A. H., Davison, J. B., Susmel, L. On the use of linear-elastic local stresses to design load-carrying fillet-welded steel joints against static loading. Engineering Fracture Mechanics, 136, pp. 38-57, 2015. 2 together the different parts. In this context, welding definitely represents the most widely used technological solution. In addition, welding plays a primary role in the repair and life extension of components and structures.Although several welding technologies are used in manufacturing, arc welding is the most commonly adopted joining technology. As far as conventional arc welding is concerned, producing high quality weldments requires experienced welders capable of properly setting the necessary technological parameters. The overall quality of a weld mainly depends on the material microstructural features as well as on the geometry/size of the seams [3]. In particular, given the parent material, the most important technological variables affecting the quality of arc welded joints can be summarised as follows [4,5]: preparation of the parent material, welding current, welding voltage, welding speed, shielding gas, metallurgical characteristics of the filler material and number/sequence of passes.The above parameters are important also from a structural integrity point of view. In fact, the overall static strength of welded joints depends not only on the weld bead's geometrical features, but also on the microstructural features of the material in the vicinity of the seams themselves (especially the heat-affected zone) [6,7]. Further, in conventional fillet welded joints subjected to uniaxial static loading, cracks are seen to initiate at the weld roots, subsequently propagating mainly through the weld beads [8]. This cracking behaviour suggests that, to efficiently control the overall strength of fillet arc welded joints, the technological variables must be set so that an adequate level of penetration can always be reached [9].From a stress analysis point of view, if the parent and filler materials are assumed to obey a linearelastic constitutive law, the stress fields in the vi...

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