Prediction of weld toe magnification factors for semi-elliptical cracks in T–butt joints

This paper reports the background development of a set of equations for estimating weld toe magnification factors (Mk) for semi-elliptical cracks in T–butt joints. This set of equations has been included in the new British Standard BS 7910. The extensive finite element parametric study from which the database of Mk factors was generated is first reported. The parameters studied — crack depth and aspect ratios, attachment footprint, weld angle and weld toe radius — and the ranges covered are those likely to be found in real structures. The procedures for numerical modelling, analysis and stress intensity factor evaluation are described, and the effects of the various influencing parameters on the Mk factors are discussed. Estimation equations that were developed from multiple regression analyses of the database of Mk factors are detailed. The equations are shown, through statistical analyses, to be a very good fit to the database from which they were derived.