Objectives The inter-ship structure between double-layer shells is an important bridge for the transmission of acoustic vibration from pressure shell to light shell. To reduce the impact on the acoustic vibration radiation level of ships, a double-layer acoustic bridge inter-ship structure is proposed and its acoustic vibration transmission characteristics studied.

Methods The finite element method is used to establish a finite-length double-layer cylindrical shell acoustic vibration radiation model of an inter-board double-layer acoustic bridge. The differences between the sound and vibration transmission of the double-layer acoustic bridge and those of a traditional single-layer acoustic bridge structure are compared and analyzed. Finally, the influence of the double-layer acoustic bridge's structure, structural parameters and axial distribution spacing on its acoustic radiation and vibration transmission characteristics is revealed.

Results The results show that the double-layer acoustic bridge connection structure between double cylindrical shells has a better noise reduction effect than the traditional single-layer acoustic bridge structure. The effect of the "2-1" double-layer acoustic bridge structure model on reducing vibration transmission between double cylindrical shells is better than that of "1-2" and "2-2" double-layer acoustic bridge structures. Three different "1-1" double-layer acoustic bridge connection structures show similar vibration transmission reduction effects. The spacing of the bottom acoustic bridge ribs and the width of the transverse plate have a great influence on the vibration transmission reduction effect of the double-layer shell structure, while the height of the acoustic bridge has little effect. The closer the axial distribution of double-layer acoustic bridges between double cylindrical shells, the worse the vibration transmission reduction effect.

Conclusions The results of this study can provide references for the shock absorption and noise reduction design of the inter-board structures of ships.