An energy-based formulation for vibro-acoustic analysis of submerged submarine hull structures

An energy-based formulation is developed to investigate the vibro-acoustic behaviors of the submarine hull immersed in heavy fluid in the present paper. The conical-cylindrical-hemispherical coupled shell with bulkheads and ring stiffeners is considered as the theoretical model of the hull structure, which is discretized into a number of spectral elements according to the structure type. Displacement components of each spectral element are invariably expressed by a set of modified Fourier series. The external acoustic field is described by one-dimensional Helmholtz integral formulation that can be solved by the means of discretization along the generator line of the hull structure. Subsequently, the full vibro-acoustic model for the submerged hull is established by taking into account the energy of the acoustic field acting on the hull surface. The reliability and accuracy of the present method is validated by comparison of vibration and acoustic responses with those from the commercial softwares. Several examples are conducted to understand the effects of bulkheads, ring stiffeners and coupling stiffnesses on the vibro-acoustic behavior of the submerged hull, which provides some helpful information in the design of underwater hull structures.