Etude théorique et numérique du comportement vibroacoustique de plaques inhomogènes couplées à une cavité

Abstract
Our work is concerned with acoustic transmission from the outside to the inside of high speed train moving in a fluid (such as two storey T.G.V.). The modelization of this problem leads us to consider a large structure, made of inhomogeneous plates putting together, and excited by an aerodynamic (harmonic) source. In order to take into account the principal phenomena wich govern our system, we study a simplified configuration : An inhomogeneous plate, backed by a closed rectangular cavity. The theory is based on modal analysis of both plate and cavity uncoupled. The vibrations of the plate is analyzed with a RAYLEIGH-RITZ approximation.The first numerical results provide some informations about the influence of the perturbation induced by heterogeneities : for instance, we can't neglect the contribution of heterogeneities on the internal acoustic pressure when the excitation is localised on it (in the studied frequency field).