Modal coupling in the vibroacoustic responses of submerged spherical-cylindrical-spherical shells stiffened by ribs and plates

摘要

This article presents a modal decomposition method for the analysis of radiated sound power of coupled shell structures submerged in infinite heavy fluid. This method provides greater physical insight into the self-andmutual-modal radiations of the in-vacuo modes. The corresponding cross-modal radiation efficiency is defined and formulated to analyze the mechanism of the energy transfer among the structural modes. A fully coupled finite element/boundary element model is developed for a simplified submarine hull, which is composed of a coupled spherical-cylindrical-spherical shell and a series of ring stiffeners and bulkheads. The interactions of different circumferential modes of the hull are examined. Modal coupling among the n = 1 grouped modes (including rigid body modes) is carried out to reveal the cross-modal coupling characteristics of the modes in the axial direction. In addition to the cross-modal radiation efficiencies, modal sound directivity is employed to show the physical mechanism of the modal coupling. The effects of apparent relative mass on the modal coupling are also investigated. (C) 2018 Institute of Noise Control Engineering.