Role of Stress Concentration on Fatigue of Welded Joints

Abstract

ConclusionThe elastic stress concentration factor depend on the weld toe radius, weld angle, loading mode and geometry. Specific analytical formulae from Nihei et al. [9.1], Skorupa et al.[9.3], Niu and Glinka [9.5] describe the influence of theses parameters on the kt value. The use of this parameter is limited by plastic relaxation and limitations of the ‘hot spot’ approach.Traditional design of welded joints against fatigue is made according to codes such as Eurocode III [9.8], the geometric and effective stress approach [9.7] and the linearised stress code [9.9]. The design principle is a specific fatigue reference curve for each class of weld excluding the influence of material properties.Innovative methods such as the local strain [9.10] and volumetric methods [9.11] take into account, in a precise manner, the cyclic material behaviour.Recent methods which consider fatigue initiation and crack growth is relevant to the local approach adopting the concept of notch stress intensity factor [9.13; 9.17]. The synergic effect between mechanical loading and corrosion in welded joints can be seen by applying a model which couples the effective stress and the corrosion current [9.17].