Assessment of welded joints by SED approach accounting for misalignments and geometrical imperfections

Among recently introduced fatigue assessment approaches, the ones based on the notch stress intensity factor (N-SIF) concept appear to be very promising, both because of their theoretically soundness and because of the possibility of straightforward computation of parameters believed to govern the fatigue process. Actually, while such approaches can be considered in between stress-based approaches and crack propagation ones, quantities like N-SIF and strain energy density in a control volume can be evaluated by finite element analysis according to nowadays well-established procedures, mostly already implemented in commercial FEM software. The present study moves from a former one, dealing with butt joints between typical shipbuilding shell plates, and aims at assessing how the misalignment influences the fatigue strength estimation when applying the strain energy density approach. Eventually, the capabilities of such approach in accounting for misalignments is demonstrated and results are found in agreement with magnification factors currently recommended by guidelines and rules when applying other, stress based, fatigue assessment approaches.