Fatigue strength assessment of three-dimensional welded joints with the JV parameter

In this paper, the use of the J-integral (namely JV) is extended to three-dimensional sharp V-notches to evaluate the fatigue life of welded joints under complex loading. In order to simplify the procedure, JV is evaluated as a line integral on the free surface of the V-notch without defining a path contour inside the material. The length of the integration path depends on the critical characteristic length ρ* equal to one millimetre for welded joints made of steel. The JV is evaluated along the weld profile and the position of maximum JV is numerically calculated by means of the FE method. A relationship between the J integral and the JV is found in the case of mode III loadings. Finally, welded joints obtained with an RHS profile made of steel and subjected to tensile loading, bending and torque have been analysed.