ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

4pPAb11. Structural and acoustic responses of mass-spring loaded elastic cylindrical shells: Spectral formulation and ray synthesis.

Jin-Meng Ho

SFA, Inc., 1401 McCormick Dr., Landover, MD 20785

Naval Res. Lab., Washington, DC 20375

This paper applies the spectral theory to the formulation of both the pressure field and the displacements of a source-excited cylindrical shell with the internal attachment of a mass-spring substructure at two arbitrary locations. Respective alternative representations in the series and integral forms, with a distinct correspondence between each other, may be readily written down. The series form generalizes Guo's solution which is limited to the diametrical attachment of the spring to the shell [Y. P. Guo, J. Acoust. Soc. Am. 91, 926--938 (1992)], while the integral form is suitable for further ray acoustic reductions which are also affected here. Furthermore, the internal loading is equivalent to the spring-shell interaction forces acting at the attachment locations. The radiation from the induced forces superimposed with the contribution due to the empty shell then gives rise to the total structural and acoustic responses of the internal-shell-fluid system. The equivalent forces, which in general have both normal and tangential components, are functions of the shell displacements at the attachments; the latter may be in turn determined from their continuity conditions and evaluated either by normal-mode series or the geometrical acoustics fields and shell guided modes. [Work supported by ONR.]