The effects of dynamic absorbers on the forced vibration of a cylindrical shell and its coupled interior sound field

The vibration and the coupled interior sound field of a closed, elastic cylindrical shell, due to both external point forces and distributed forces, are separately studied in this paper. Multiple dynamic absorbers are then attached to the shell to reduce the vibration and the consequent interior acoustic sound pressure. The dynamic response of the shell and the sound pressure in the interior acoustic cavity, under the influence of absorbers, are obtained using the techniques of substructure synthesis and modal expansion. Analytic solutions are derived. Numerical examples are then studied and discussed. The results show that the addition of dynamic absorbers, if correctly positioned, can successfully reduce the vibration of the shell and the interior acoustic pressure of the sound field enclosed by the shell. Further, the best absorber arrangement is found to be strongly dependent on the type of external forces present. Some general guidelines on absorber design for the reduction of the shell vibration and its interior noise are offered in conclusion. The effects of varying the parameters of the absorbers such as mass, stiffness, and the location of the absorber are also investigated for the two types of external forces. (C) 1997 Academic Press Limited.