In this paper, the acoustical treatment of double-panel structures lined with poroelatic materials is predicted using analytical method in order to study the effective usage of the various boundary conditions of porous layer and to identify the effective parameters on the transmission loss of the multilayer systems. Therefore, inertia and viscous coupling along with thermal and elastic coupling should be considered in transfer stress dynamic and stress-strain relationships for an elastic porous material based on Biot theory. Then, the governing equations of the wave propagation in an elastic porous material are briefly considered and the general forms for the stresses and displacements within the porous material are given. Applying various boundary conditions and solving these equations with Matlab code simultaneously, the transmission loss of these structures is calculated. The results from the analytical method are compared with the SEA madel and the experimental data with excellent agreement is observed. Finally, the influence of effective parameters of this structure with various boundary conditions on the transmission loss of the multilayer systems is studied. The results have been shown that the transmission loss of double-panel structures lined with a layer of porous material can depend critically on the method of mounting the porous layer to the facing panel. Manuscript profile

Automobile manufactures are persistently trying to develop comfort of passengers by improving different specification such as decrease of sound level in engine compartments. There is a main problem that the noise generated in air intake systems may be disgusting. Statistical energy analysis is a suitable method for acoustical- vibration analysis of structures in high frequency range. In this paper, the air intake system of an engine compartment is modeled using SEA. The transmission loss through the intake duct is calculated with importing CAD model and creating subsystems at high frequency range. In addition, comparing the results of fully modeled of intake systems with current experimental data, shows a good accuracy of results especially in high frequency range. Furthermore, the influence of inserting porous material is studied. Manuscript profile