ANALYSIS OF WELD TOE RADIUS EFFECTS ON FATIGUE WELD TOE CRACKS

Stress analysis of as-welded and weld toe ground fillet welded joints was carried out for four different weld toe radii (0.5, 1.0, 2.5 and 5 .0 mm). This provided the stress distributions through the thickness o f the plate and the stress concentration factor was determined by extr apolation to the weld toe surface. Closed form stress distribution equ ations were curve-fitted to the finite element results. Stress intensi ty factor computations for weld toe cracks were carried out using a we ight function method and finite element techniques. Short weld toe cra cks with crack depth to plate thickness ratios between a/T = 0.001 and a/ T = 0. 1, were modelled and analysed for the weld toe radii of 0-5 , 1-0, 2.5 and 5.0 mm. For the finite element analysis a virtual crack extension method was employed in computing the linear elastic J-integ ral and the average value for three contours was used to calculate the stress intensity factor. The stress intensity factor is presented as a stress concentration magnification factor (Mk) multiplied by the bas ic crack geometry for a single edge cracked plate (SECP). This was emp loyed in a fatigue crack propagation analysis where the fatigue endura nce curves were evaluated.