A Notch Intensity Factor Approach to the Stress Analysis of Welds

Abstract

In the context of linear elastic stress gradients that are present in welded joints, a stress field approach based on notch stress intensity factors is presented with the aim of describing stress distributions in the neighbourhood of weld toes, since fatigue strength is dependent on such distributions. This paper summarizes the analytical fundamentals and gives an appropriate definition of the parameters for stress components under opening and sliding modes. Then, by comparing the expected results with those obtained by numerical analysis, the contributions of the symmetric and skew‐symmetric loading modes are quantified for different geometries, and summarized into concise expressions which also take into account the influence of the main geometrical parameters of the welded joint. The range of validity and the application limits of this field approach in the presence of weld toe radii are discussed. Finally, a synthesis of experimental fatigue strength data based on the new field parameters is reported.

Local strain energy density for the fatigue assessment of hot dip galvanized welded joints: some recent outcomes

“…The volume over which the strain energy density is averaged is then a circular area Ω of radius R 0 centred at the notch tip, symmetric with respect to the notch bisector (Fig. 4), and the stress distributions are those by Williams [18], written according to Lazzarin and Tovo formulation ( [19]). Dealing with sharp Vnotches the strain energy density averaged over the area Ω turns out to be:…”

A Review of the Fatigue Strength of Load Carrying Shear Welded Joints

“…These parameters may vary not only for the different faces of the same design, but also within the same interdiction; moreover the radius of the tep may be considered to be equal to zero or tends toward zero (Atzori, 1985;Lazzarin and Tovo, 1998).…”

“…An approach based on factor of stress Notch Intensity (NSIF) has been proposed by Lazzarin and Tovo (1998) and for the prediction resistance to tiredness. This approach take into account both the form of welding string of beads (angle of the finger of the foot of welding, or the opening angle notch) and radius of the weld toe (notch peak radius).…”

“…determined NSIFs pad (or, in the case of bigger tasks, spring plasticdetermined by stress the notch or factors of intensity strain) may describe the voltages of the region of toe of weld, quantifying the intensity of the distributions of stress on the basis of conditions of orders of the Williams solution (1952). NSIF approach was originally proposed to estimate the stage of initiation of the cracks (Boukharouba et al, 1995;Verreman and Nie, 1996), but only later was demonstrated later that NSIFs parameters are able to predict the service life of the fatigue of the welded connections (Livieri and Lazzarin, 2005;Lazzarin and Tovo, 1998;Atzori et al, 1999). In fact, a large quantity of life to fatigue for welded structural is spent at the depth of the crack in the short term, within the region governed by the singularities V-notch: Therefore, nucleation and increase the short cracks are dependent on the distributions of stress present in the component Nesfari-stopper.…”

“…In fact, a large quantity of life to fatigue for welded structural is spent at the depth of the crack in the short term, within the region governed by the singularities V-notch: Therefore, nucleation and increase the short cracks are dependent on the distributions of stress present in the component Nesfari-stopper. The original data from Maddox (1987) and Gurney (1991) for transverse load without carrying the file welded joint faces have been retested the Lazzarin and Tovo (1998). The original S-data N has been largely wasted, because of the large variation of the parameters geometric parameters of the joints.…”