SPATIALLY LOCALIZED RANDOM FORCING OF FLUID-LOADED ELASTIC PLATES

The response of a fluid-loaded, linearly elastic plate to a spatially localized, random forcing and the radiation of sound therefrom is form ulated in terms of two-point coherence functions. Emphasized is the us e of linear-phased arrays, of displacement meters on the surface of th e plate and of hydrophones located in planes removed from the plate, i n an envisioned model experiment. The formulation shows the total expe riment to be described via an ordered sequence of operators, termed pr opagator/filters. Analytic and numeric investigation of these operator s are accomplished for ''typical'' experimental scenarios. Of particul ar interest is the complicated manner in which the ''potential for int erference'' of widely separated, in physical or in spectral space, com ponents of an acoustic signal is accommodated in a coherence function formulation. This potential renders a Wigner function, a transformed c oherence function, description of a phase space, somewhat inconvenient for discussing the propagation and scattering of deterministic signal s. Randomness, which typically eliminates this potential for interfere nce, can make for a convenient Wigner function framework.