Forced Harmonic and Random Vibrations of Concentric Cylindrical Shells Immersed in Acoustic Fluids

Abstract

The forced harmonic and random vibrations of an elastic cylindrical shell surrounded by an inviscid fluid and concentrically contained by another thin elastic shell which itself is immersed in another inviscid fluid of infinite extent is considered. The motion of the shells and fluids is assumed independent of the axial coordinate. The motion of the shells is described by a theory which accounts for transverse shear and rotatory inertia. The motion of the fluids is described by the classical wave equation. Expressions for the acoustic pressure at the outer surface of the inner shell and the inner and outer surfaces of the outer shell are obtained along with the displacements (velocity) at these surfaces. Numerical results for the near- and farfield acoustic pressure are given for the case wherein the interior of the cylinder is subjected to diametrically opposed point forces which vary either harmonically or randomly with time. The random excitation is assumed to be spatially uncorrelated, broad-band white noise.