Waterborne Sound Transmission Loss in Finite Double-Plate Sandwich Structures with Poroelastic Cores

This research investigates the sound transmission loss (STL) characteristics of finite double-plate sandwich structures featuring poroelastic cores and air gaps under external water flow conditions. A theoretical framework, based on Biot’s theory and modal decomposition, is developed to analyze fluid-structure interactions, convective flow effects, and various boundary conditions. The study highlights the influence of air gap resonances, the added-mass effect from hydrodynamic loading, and asymmetric plate thickness distributions on STL performance. Results indicate that optimized plate asymmetry enhances STL by leveraging mass-stiffness imbalances, while the directional dependence of incident acoustic waves significantly affects transmission outcomes. These insights offer practical design strategies for developing lightweight, broadband underwater acoustic insulation systems tailored for dynamic marine environments.