Influence of weld-induced distortions on the stress magnification factor of a thin laser-hybrid welded ship deck panel

The limited knowledge about fatigue behavior and lack of analytical solutions for distorted thin plates are predominantly limiting their application today. This paper focuses on finding the most influential distortion parameter that dictates the fatigue strength at the butt weld of a laser-hybrid welded 4 mm thin ship deck panel. A FEA based sensitivity analysis method is employed to identify the influence of the distortion parameters. The results from the experimental validation showed that the distortions of the distorted deck plate on either side of the butt weld could be simplified with 4-point and 3-point splines on longitudinal and transversal direction, respectively. The most important distortion parameters are local angular misalignment, the distortion magnitude and location of local maximum distortion close to the butt weld. The distortion parameters further away from the weld has a minor influence on the structural stress at the butt weld. Furthermore, the results showed that the local angular misalignment can independently provide a better estimate of stress magnification factor k_m compared to any other distortion parameters.