HIGH-FREQUENCY VIBRATION AND ACOUSTIC RADIATION OF FLUID-LOADED PLATES

To investigate the high-frequency vibration and acoustic radiation of fluid-loaded structures, the model problem of a simply-supported plate excited by a random pressure field is considered. The analysis is sta ndard and yields a set of modal equations coupled by acoustic interact ion terms. These terms not only complicate the equations, but also app ear in a form that is difficult to evaluate numerically at high freque ncies and mode numbers. The latter problem is resolved by deriving asy mptotic expressions for the acoustic coefficients, and computational s olution of the full, coupled modal equations then becomes feasible. By comparing the results with the 'diagonal approximation' (the solution when coupling is ignored), an improved characterization of the physic al nature of the acoustic coupling is obtained, and new conditions for its neglect are specified. The conditions are not stringent, implying that the diagonal approximation will often be valid, and raising the possibility of applying statistical energy analysis (SEA) to significa ntly fluid-loaded structures. Modified sea results are derived, and fo und to compare well with the modal solutions.