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Presentation
Modelling of the acoustic radiation of a structure covered by a porous layer
NOVEM (2005)
  • Olivier Doutres
  • Nicolas Dauchez
Abstract
In many applications, porous materials such as polymers foams are attached to a structure subjected to vibration. This allows to diminish vibration by increasing structural damping or to reduce noise level in cavities by sound absorption. The radiation efficiency of the coupled system is studied. An analytical model has been carried out, separating the acoustical and vibratory behaviors: - The vibratory analysis is based on a dynamic study of an equivalent plate of the coupled system. In this case the porous layer is considered as a viscoelastic layer. - In the acoustical analysis, a surface impedance is applied on this equivalent plate taking into account the fluid-structure coupling effects in the porous layer according to Biot theory. As expected, the porous layer decreases global acoustic radiation level except for some frequency ranges. At these frequencies, increased acoustic radiation is due to skeleton resonances in the thickness of the layer. These amplificated vibrations of the coupled structure obviously limit absorption and isolation efficiencies of the porous material. Experimental measurements are then performed using a clamped circular plate backed by a porous layer. The agreement between experimental measurements and theoretical predictions validates the model. This method could be used in further work to characterize the mechanical properties of a porous layer submitted to high dynamic motion.
Publication Date
April, 2005
Citation Information
Olivier Doutres and Nicolas Dauchez. "Modelling of the acoustic radiation of a structure covered by a porous layer" NOVEM (2005)
Available at: http://works.bepress.com/olivier_doutres/16/