چكيده به لاتين
in this thesis, "Acoustic Modeling and Performance Analysis of Porous Media in Noise Reduction of Passenger Wagons" is provided. first, Porous media and its acoustical and physical characteristics are introduced. then theories of Sound propagation in these materials are expressed. theories divide into two parts: the theory of sound propagation in rigid and the theory of sound propagation in elastic porous materials. Finite Element Modeling (FEM) Methods and the noise sources of trains are described, then a sample porous Foam that is using in wagons and also a multilayer one, are modeled in COMSOL. the modeling uses the Biot-Allard as the comprehensive method. next, the results of the modeling are compared with the existing results in the references. Acoustic behaviors of these foams are investigated with changes in physical characteristics. as a result, effective variables are identified for the next step that is optimization. Nelder-Mead algorithm for optimization in critical frequencies is used, so the best combination of multilayer porous foam for noise reduction is introduced.
Keywords: Acoustics, Porous Media, Noise reduction, Biot-Allard theory, FEM, Optimization
