Acoustic Characteristics of a Plate Silencer With a Flexible Back Cavity Under Arbitrary Boundary Conditions

The flexible back cavity (FBC) plate silencer is composed of an FBC and a flexible inner plate. Through the coupling of the sound field with the flexible inner and outer plates, the transmitted sound energy of the downstream is reduced, and it has a good broadband muffling effect at low frequencies. In order to obtain the transmission loss (TL) of the FBC plate silencer under arbitrary boundary conditions, this paper establishes the acoustic-vibration coupling model of the FBC plate silencer based on the energy principle. Translational restraints and rotational restraints are used to simulate the arbitrary boundary conditions of the flexible plate, and then the influence of the boundary conditions of the flexible plate on the TL is analyzed. The results show that the results of the proposed method are in good agreement with the finite element method (FEM) results. The structural boundary restraint has a significant influence on the acoustic characteristics of the system, and the rotational restraints suppress the muffling effect. By appropriately releasing the translational restraints, a better low-frequency broadband muffling effect can be achieved, with the minimum muffling frequency reduced by 44.8% and the muffling bandwidth broadened by 57.4%.