Numerical investigation on the buckling response of stiffened panel subjected to biaxial compression with non-linear equivalent single layer approach

A ship experiences different loading conditions during service under which a structure composed of stiffened plates can buckle. Panel buckling can lead to an overall collapse of the ship hull girder that determines the hull girder ultimate strength. In the context of ultimate strength assessment, it is imperative to minimize the computational cost required for the analysis. Therefore, replacing the three-dimensional FEM stiffened panel model with a two-dimensional equivalent single layer (ESL) plate is a cost-efficient and attractive alternative. However, the premise in this switch from 3D to 2D is ESL accuracy in representing a stiffened panel's various buckling modes, which depend on the panel topology and the boundary condition. Therefore, we investigate the response of an equivalent single layer (ESL) plate representing a stiffened panel under different buckling modes. Because ESL is an asymmetric membrane, the modification of the geometry of the stiffened panel will change the buckling modes. The concern of buckling modes in this paper is (i) local buckling of the plate and web stiffener and (ii) local lateral torsional buckling of the stiffener. Results show that ESL can predict accurately the effect of local buckling for biaxial compression.