A traction stress based shear strength definition for fillet welds

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.