SOUND RADIATION BY FINITE CYLINDRICAL RING STIFFENED SHELLS

An analytical study of radiation by a finite, stiffened cylindrical shell is presented. The model of stiffener used allows one to treat hollow cross-section cases encountered in industry. The driving force is applied on the stiffener or directly on the shell and can be radial, tangential or longitudinal. Fluid and structure equations are solved with modal analysis and use of the in vacuo non-stiffened basis. This leads to the calculation of radiation impedances and generalized mass and stiffness terms of stiffeners. Theoretical results are presented in radiated power, radial quadratic velocity and radiation coefficient (in both air and water); they show the influence of stiffeners on the vibro-acoustic shell behaviour in both fluids. Parameters such as shell and stiffener structural damping, relative location of force and stiffeners, and force direction are investigated. This gives some guidelines for noise reduction. © 1990.