Calculation of the scattering from a ribbed cylinder by means of finite-element methods

Abstract

The modeling of a large structure using finite elements, for the purposes of calculating radiation and scattering, is severely limited by the size of the matrices which must be inverted. In this paper, we investigate the application of the general theory of periodic structures [L. Brillouin, Wave Propagation in Periodic Structures (McGraw-Hill, New York, 1946), 2nd ed.] to the scattering of acoustic waves from a ribbed cylinder. This theory, when combined with finite-element methods, provides us with a powerful analysis technique. Results are presented on the backscattered pressure levels and structural displacements. The relationship between the normal modes of the structure and the displacements produced by an incident plane pressure wave are discussed. [Work supported by NOSC Internal Research Fund made available by the Director of Navy Laboratories.]