Propulsive performance and structural response of sandwich composite marine cycloidal propeller

This study proposes a composite sandwich model (CSM) for a Marine Cycloidal Propeller (MCP) unit, developed to achieve significant weight reduction and improve propulsion efficiency. A coupled boundary element method and finite element method (BEM–FEM) framework is used to evaluate the propulsive characteristics and structural response of the MCP blade. The hydrodynamic performance is validated with existing open-water experimental data while the structural behavior of the sandwich configuration is verified through three-point bending test results. A comparative assessment is conducted between a conventional metal model (CMM), a laminated composite model (LCM), and the proposed CSM blades. Parametric studies examine the influence of the core material, core thickness, and skin fiber orientation on the structural response. The findings indicate that the CSM achieves greater weight savings than both the CMM and LCM designs, with enhanced propulsive characteristics at lower advance coefficients. The CSM blade with a 50% core percentage achieves approximately 89% weight reduction compared to CMM, outperforming even the LCM which achieves 80% reduction. The ROHACELL 200 WF core material offers the best mechanical performance with minimal deformation, while lower modulus foams induce greater structural deflection. Reducing the core percentage improves bending stiffness and decreases tip displacement and twist angle, with a core percentage of 50% identified as the optimum value. Regarding fiber orientation, with an angle-ply sequence of +15°/−15° identified as optimal for controlled deformation with minimum displacement and twist angle. This study provides insights into the structural behavior of sandwich composite cycloidal propellers and supports the development of lighter, more efficient marine propulsion systems.