Abstract:

In general, an acoustic coating is applied uniformly on the surface of a fluid-loaded structure to minimize acoustic radiation and scattering. There are, however, some inherent advantages to optimize the distribution of the coating around areas from which the acoustic radiation appears to emanate. This would be analogous to the application of damping treatment in areas of a vibrating structure which have high vibration levels. In the case of the acoustic radiation the problem is more complex because of the coupling between the acoustic fluid and the structure. In this paper, the acoustic radiation from a partially coated fluid-loaded structure, of infinite extent and excited by a point or line force, is examined by developing an analytic/numeric solution. The solution follows along some of the procedures that the authors developed in previous work related to the scattering from fluid-loaded plates and shells. The coating is assumed to provide mainly a decoupling layer between the acoustic medium and the structure; that is, it does not add mass or stiffness to the base structure. The influence of added mass or stiffness of the coating can be included as an added inhomogeneity and treated separately in the solution. [Work sponsored by NSWC-CD.]