FATIGUE ANALYSIS OF T JOINTS IN PLATES

The results presented in this paper refer to a fatigue life study of plate T joints predominantly loaded in bending. Crack initiation life was taken into account in the analysis using recently developed models. The crack propagation model was based in the Mk factor computed with the Glinka weight function method. The influence of the ratio L/B (leg to leg distance over main thickness) on the Mk values was obtained. The Mk results were also obtained as a function of the radius of curvature at the weld tow which is the controlling parameter of the Mk results. Crack aspect ratio curves (a/c against a/B) were also derived and compared with experimental observations. The residual stress distribution was also analysed and an assessment was made of their values in the a/c against a/B curves. The fatigue crack propagation life was computed by integration of Paris law type. A semi-elliptical crack growth model was assumed with Mk the magnifying factor of the basic K equation. A comparative study is also presented of the crack initiation and crack propagation contributions for fatigue life. This could help the designer to define the most appropriate model for his fatigue life problem. Theoretical predictions of fatigue life (crack propagation plus crack initiation) were made and compared against experimental results in the literature. Results were obtained for different main plate thicknesses and good agreement was obtained.