Acoustical properties of macroscopically inhomogeneous porous medium
Résumé
A 140mm thick material sample with a distinctive pore size stratification was produced in the laboratory from polyurethane binder mixed with recycled particulates. This material exhibits a high acoustic absorption across a relatively broad range of frequencies. It was shown that the observed absorption coefficient spectra depend clearly on the sample orientation. The state vector formalism and Peano series expansion were adopted to explain the observed acoustic absorption behaviour of the developed material sample. A Biot-type model was used to link the acoustic pressure gradient with particle velocity in the oscillitary flow in the material pores. The complex dynamic density and bulk modulus of the equivalent fluid in the material pores were predicted using a computationally efficient model based on the Pade approximation. A good agreement between the proposed theory and the obtained experimental data for the acoustic absorption coefficient was observed.
Domaines
Acoustique [physics.class-ph]
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