Abstract:
A thin elastic rectangular plate, with clamped boundaries, extended by an infinite perfectly rigid plane baffle is considered. Both half-spaces are occupied by a gas. A sound source is located on one side of the plate. One is interested by the sound field transmitted through the plate. The boundary value problem governing the system is solved by two methods: A boundary element method, which gives a numerical solution of the exact equations; and a series representation of the solution in terms of the fluid-loaded plate resonance modes, an analytical approximation which is obtained by a perturbation technique (the ratio of the gas density to the surface mass of the plate being the small parameter). The discrepency between the two methods does exceed 1 dB or so: This shows that the perturbation method, which is much less time consuming than the BEM, is a very powerful prediction tool. The Laboratoire de Mecanique et d'Acoustique in Marseille has two anechoic rooms, which are connected by an aperture. A steel plate has been built inside the aperture. The measured acoustic pressure transfer function between points located on both sides of the plate is well predicted by the numerical methods. [This research has been partly sponsored by the Ministere de l'Environnement and by the Programme International de Cooperation Scientifique Vibro-Acoustique dans le Domaine des Transports initiated by the CNRS.]