Normalized inverse characterization of sound absorbing rigid porous media.

On representativeness of the representative cells for the microstructure-based predictions of sound absorption in fibrous and porous media

Realistic microstructure-based calculations have recently become an important tool for a performance prediction of sound absorbing porous media, seemingly suitable also for a design and optimization of novel acoustic materials. However, the accuracy of such calculations strongly depends on a correct choice of the representative microstructural geometry of porous media, and that choice is constr...

Derivation of a Frequency Independent Criterion to Determine the Limp Model Validity for Highly Porous Sound Absorbing Materials Frequency Independent Limp Model Criterion 1

A frequency independent criterion to determine the limp model validity for highly porous sound absorbing materials is investigated. Although limp model is derived from the Biot theory assuming that the porous frame has no bulk stiffness, it is shown that this model can be used for highly porous materials since the criterion is respected. Abacus giving the criterion limit as function of the poro...

Inverse methods of determining the acoustical parameters of porous sound absorbing metallic materials

Porous metallic material has become a kind of typical multifunctional material with the quick development of advanced manufacturing and forming process technologies in past years. At present, it has also been a structural function material with the characteristics of ultra-light weight, high specific strength and rigidity. As a sound absorbing material in noise control engineering, the acoustic...

Multiple scattering of acoustic waves and porous absorbing media.

Porous media like air-saturated polymer foams with open cells, have a nontrivial frequency-dependent absorption that arises due to viscous and thermal effects at the scale of the rigid frame microstructure. In order to produce multiple scattering at ultrasonic frequencies, mesoscale scatterers are introduced in the porous medium host. The effective wave number of such a multiscale medium should...

Sound Propagation in Rigid Porous Media: Non-local Macroscopic Effects Versus Pores Scale Regime