Objective This paper investigates the vibro-acoustic characteristics of a floating raft-hull coupling system based on the generalized variational principle, aiming to improve the acoustic performance of floating raft vibration isolation systems.

Methods The floating raft-hull coupling system was simplified into a coupled dynamic model consisting of a reinforced cylindrical shell, double-layer plates, springs, and the external acoustic field. The vibration energy equations for the structural domain were derived using the generalized variational method, and the boundary element equations for the acoustic field domain were discretized based on the Helmholtz integral equation. The governing equations of the coupling system were established by expanding the structural displacement and acoustic pressures using Fourier series and orthogonal polynomials. The accuracy of the proposed semi-analytical model was validated through finite element method (FEM) simulations. Furthermore, this study systematically explored the effects of various design parameters and optimization strategies, including the isolator stiffness, elastic modes of the raft, raft-to-equipment mass ratio, and hull structural parameters, on the vibro-acoustic performance of the coupling system.

Results The results showed that the proposed model agreed well with FEM analysis, verifying the accuracy of the dynamic analysis method and providing high computational efficiency and clear physical insights.

Conclusions The study concludes that reducing the isolator stiffness, increasing the stiffness of the raft structure, increasing the raft-to-equipment mass ratio, and increasing the height of the hull's ring stiffeners can significantly improve the system's acoustic performance. These findings offer theoretical guidance for the dynamic design, analysis, and optimization of floating raft vibration isolation systems and are valuable for practical engineering applications.