A traction stress based shear strength definition for fillet welds

Abstract

In this paper, a traction stress based shear strength definition is presented for correlating weldment test data obtained from standard specimens such as those stipulated by AWS B4.0 as well as for applications in general structural design applications when finite element methods are used. With this proposed approach, well-documented discrepancies in shear strength between transverse and longitudinal shear tests can now be reconciled, resulting in a single shear strength value regardless of specimen types and loading conditions. The method should provide a basis for achieving a quantitative weld sizing in fillet weld design for structural applications. The paper starts with a brief description of major issues associated with strength data interpretation using the conventional shear stress formula given in AWS B4.0 which is widely used by various industries. After posing a series of candidate static failure criteria, an existing finite element solution technique for dealing with stress concentration effects on fatigue is then extended for applications in determining stress parameters that can be related to shear strength in standard shear test specimens. A large amount test data are then analyzed to judge the most appropriate failure criteria for shear strength characterization of fillet welds. An analytical solution is also developed both for validating the proposed shear strength definition and for gaining theoretical insights, e.g. on stress/strength relationship as a function of fillet weld and fillet weld geometry.

Strength analysis of fillet welds under longitudinal and transverse shear conditions

“…Their results showed that significant shear stress concentration exists at weld ends (at "machined slot" positions in longitudinal shear specimens as shown in Fig. 1a), which can be attributed to typically lower shear strengths in longitudinal shear specimens compared with those in transverse shear specimens, as reported in the literature [15]. However, more test data are needed in order to both validate the findings given by Nie and Dong [15] and develop correction schemes for using Eq.…”

“…1a), which can be attributed to typically lower shear strengths in longitudinal shear specimens compared with those in transverse shear specimens, as reported in the literature [15]. However, more test data are needed in order to both validate the findings given by Nie and Dong [15] and develop correction schemes for using Eq. (1) for fillet weld strength characterization.…”

“…Encouraged by an earlier investigation by Nie and Dong [15], this study further extends the traction stress method for investigating its ability for correlating a large amount of fillet weld shear strength test data recently completed in a companion experimental testing program outlined in Ref. [8].…”

“…The former was repeatedly confirmed experimentally on transverse shear specimens by various researchers ( [2,9e14]). The latter has recently been illustrated by using a finite element based traction stress method by Nie and Dong [15] in their re-evaluation of some existing test data reported in literature. Their results showed that significant shear stress concentration exists at weld ends (at "machined slot" positions in longitudinal shear specimens as shown in Fig.…”

“…In this paper, we first outline the traction stress approach for shear strength analysis proposed by Nie and Dong [15] with a focus upon its specific implementation in analyzing specimens of interest in this study. After demonstrating its finite element mesh-insensitivity, the traction stress method is used to compute peak shear stresses on specimens under longitudinal and transverse shear conditions involved in a companion strength test program as outlined in Ref.…”