Shape characterization and impact on the structural behavior of initially distorted, 4-mm thick ship-deck stiffened panels

The shipbuilding industry aims at innovative design solutions for high-performing, lightweight structures. In cruise ship superstructures this translates, for example, into the design of thin-walled decks. Due to welding-induced, curved distortions, the fatigue life assessment of these structures cannot be based on the current fatigue design recommendations, which assume flat distortions. In this regard, this study investigates the panel plate field distortion shape and the stress concentration in the proximity of the weld by experiments and Geometrically Nonlinear Finite Element Analysis (GNL-FEA). Distortions are measured on 4-mm thick ship-deck panels, which are exposed to monotonic tensile test. The shape characterization considers the effect of structural continuity and boundary conditions, i.e., the cutting from the ship block and clamping of the panels in the test set-up. The numerical analysis highlights significant nonlinear secondary bending caused by curved distortions, despite acceptable misalignment amplitudes as defined in the current shipbuilding design standards.