Double-panel partition structures have increasingly found applications in modem buildings, vehicles, aerospace and aeronautical structures etc., due to their superior sound insulation properties over single-panel configurations. In order to gain a fundamental insight into the sound isolation mechanism of these structures, an analytical approach is developed to investigate the vibro-acoustic performance (including dynamic responses and sound radiation) of a clamp-mounted rectangular double-panel partition subjected to a uniform plane sound wave. The clamped boundary constraint is considered by applying a relevant modal function. A double Fourier series solution reflecting the dynamic responses of the structure is first obtained by employing the weighted residual (Galerkin) method. The radiating acoustic pressure is then analyzed by a Helmholtz integral for the far radiating field. To better understand the sound insulation mechanism, the dynamic responses of the two panels and the spatial distributions of the radiating acoustic pressure are visualized. Obtained numerical results clearly demonstrate the different mass-air-mass resonance effects for different incidence angles. It is shown that the presence of the mass-air-mass effect exerts a significant influence on the radiation efficiency and sound insulation capability of the double-panel structure. The emergence of increasingly complicated panel modal shapes suggest the presence of higher-order vibration modes when the incidence frequency increases.
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