An Experimental and Analytical Study of the Fatigue Life of Weldments with Longitudinal Attachments 2001-01-0085
Both the experimental results and the analytical predictions of this study confirm that the poor fatigue performance of weldments with longitudinal attachments is due to poor weld quality which in turn leads to either a cold-lap or a very small weld toe radius. as well as to the combination of a very high 3-D stress concentration, and very high tensile residual stresses. Consequently, a specially designed stress-concentration-reducing part termed “stress diffuser” incorporated in the wrap-around welds at the ends of the longitudinal attachments increased the fatigue strength of longitudinal attachments to equal that of transverse attachments but only when cold-laps were eliminated.
The fatigue life predictions made using the a two-stage Initiation-Propagation (IP) Model were in good agreement with the experimental results. Procedures for correcting for the curved shape of the crack path are investigated. Cold-lap defects were predicted to eliminate the fatigue crack initiation life but to affect very little the fatigue crack propagation life.