A new analysis of the strength of some simple fillet welded connections

A traction stress based shear strength definition for fillet welds

“…21 However, almost all these recent developments have been focused upon evaluation of fatigue of welded joints dominated by weld toe cracking and only to a limited extent by weld root cracking. 23 As far as static shear failure is concerned, an existing body of knowledge such as those by Kato and Marta 5 and many others 12–19 suggests that a direct application of conventional elastic stress analysis procedures in characterizing static shear failure is not adequate due to significant plastic deformation proceeding to typical static shear failures. Instead of pursuing detailed elastic–plastic stress analysis procedures already demonstrated by various earlier researchers, 12–19 this paper will focus upon extending the existing nodal force based traction stress method 20,21 to applications for characterizing static shear strengths.…”

“…There have been numerous attempts in the literature to develop analytical arguments so that the two aforementioned issues can be effectively addressed for an improved understanding of static shear failure behaviors in fillet-welded joints and an effective interpretation of shear strength test data from standardized shear test specimens. 12–19 For instance, a finite element based limit analysis procedure was recently used for standard longitudinal and transverse test specimens; 18 Miazga and Kenney 15 conducted a detailed experimental and finite element investigation by systematically varying loading angle of a series of specimens varying from standard transverse shear to longitudinal shear. Although with a varying degree of success, the results available so far cannot be easily generalized due to various assumptions made, some of which are rather questionable.…”

“…Although with a varying degree of success, the results available so far cannot be easily generalized due to various assumptions made, some of which are rather questionable. As an example, Kamtekar 14 artificially introduced vertical shear force ( P ’) on the vertical fillet leg and a normal force ( P ’) on the horizontal leg in studying transverse shear conditions (see Figure 6), both of which cannot be justified since they are physically not present for the two shear conditions studied (see Figure 1). Note that P ’ equals P in magnitude in Kamtekar.…”

“…Note that P ’ equals P in magnitude in Kamtekar. 14 Longitudinal shear was treated in a similar manner with a set of normal forces being introduced using a trial-and-error scheme.…”

On strength criteria of fillet welds

“…In actual stress-strain diagrams of perfectly plastic materials a fluency period at constant stress s E is followed by a hardening zone in which stress rises until the ultimate (maximum) value at rupture s u is reached. As was pointed out by Kamtekar [11], this whole curve can be seen as an equivalent stress-equivalent strain curve of the material, and the stress s u can be adopted as the elastic limit at rupture. In this sense, it is well known that limit analysis theorems are independent of the behavior of the material in the period prior to reaching maximum stress, so the preceding reasoning implies replacing the actual stress-strain diagram with a bilinear one, with an elastic period extending up to s u , followed by a fluency period at constant stress s u until rupture.…”