Sustainable Marine Structures

This study investigates the ultimate strength and nonlinear structural response of metallic I-core sandwich pressure hulls as an alternative to conventional ring-stiffened submarine pressure-hull structures. A key comparative investigation is conducted between two I-core configurations that differ fundamentally in the orientation of their core webs, which are aligned either longitudinally or transversely relative to the longitudinal axis of the pressure hull. The proposed configurations are designed with approximately equivalent structural weights to the conventional ring-stiffened hull, providing a consistent basis for evaluating the influence of structural configuration and core-web orientation on the load-carrying performance. Nonlinear finite element analyses are performed using ANSYS Workbench under pure axial compression and combined axial compression with different levels of lateral pressure. The numerical modelling procedure incorporates material plasticity, large deformation effects, and initial geometric imperfections derived from linear eigenvalue buckling analysis. The ultimate strength of each pressure-hull configuration is determined from the peak axial load. The results demonstrate that core-web orientation significantly influences the nonlinear response and ultimate strength, with the longitudinal arrangement exhibiting the highest structural performance under the investigated loading conditions. This improvement is attributed to the alignment of the core webs with the axial loading direction, enhancing longitudinal load transfer, with ultimate capacities approximately 66.2% and 70.3% higher than the conventional hull at 0 and 2 MPa, respectively. These findings demonstrate the potential of metallic I-core sandwich construction as an efficient alternative for advanced pressure-hull applications.