Vibro-acoustic analysis of double-walled cylindrical shells through a novel semi-analytic method

Abstract

A novel semi-analytic model is developed for vibro-acoustic analysis of immersed double-walled cylindrical shells coupled by annular plates and annular fluid between two shells. For structural model, it is firstly divided to inner shell, outer shell and annular plates, and the inner and outer shells are further divided to narrow shell segments. By utilizing Flügge shell theory and power series method, all shell segments and annular plates are uniformly analyzed as conical shells, and they are rapidly assembled to the overall structural model via boundary conditions and continuity conditions between segments. For acoustic model, interior annular fluid region and exterior infinite fluid region are separately analyzed via the Helmholtz surface integral equation. Two surface integrals are simplified to two line integrals after expanding surface sound pressure and velocity as Fourier series, so the pressure is further expressed as displacements of all segments. Through adding the pressure to the continuity conditions, the structural model is coupled with acoustic model. High efficiency and accuracy are demonstrated via comparing vibro-acoustic results of present method with ones in the literature or calculated by coupled finite element-boundary element method. Furthermore, effects of annular plates, annular fluid and excitation on vibro-acoustics of double-walled shells are discussed.