Effects of compression on the sound absorption of fibrous materials

Castagnède, Bernard; Aknine, Achour; Brouard, Bruno; Tarnow, Viggo

doi:10.1016/s0003-682x(00)00003-7

Cited by 87 publications

(52 citation statements)

References 9 publications

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“…These systems usually exhibit interesting sound absorbing properties and are, in some respects, widely used in the transportation and building industries. While several studies have devoted considerable attention to the description of the acoustical characteristics of fibrous absorbents, [1][2][3][4] our understanding of the basic relationships between the structure and the acoustical properties of these fibrous webs is still to benefit from a better understanding. It would be particularly valuable to have a manageable set of geometrical parameters of the three-dimensional (3D) fiber web morphology, in terms of which the transport (e.g., static viscous k 0 and thermal k 0 0 permeabilities, viscous characteristic length K, high frequency tortuosity a 1 ) and acoustical properties of non-woven fibrous media could be described.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Luu

Perrot

Monchiet

et al. 2017

The Journal of the Acoustical Society of America

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The main purpose of this article is to present, within a unified framework, a technique based on numerical homogenization, to model the acoustical properties of real fibrous media from their geometrical characteristics and to compare numerical results with experimental data. The authors introduce a reconstruction procedure for a random fibrous medium and use it as a basis for the computation of its geometrical, transport, and sound absorbing properties. The previously ad hoc “fiber anisotropies” and “volume weighted average radii,” used to describe the experimental data on microstructure, are here measured using scanning electron microscopy. The authors show that these parameters, in conjunction with the bulk porosity, contribute to a precise description of the acoustical characteristics of fibrous absorbents. They also lead to an accurate prediction of transport parameters which can be used to predict acoustical properties. The computed values of the permeability and frequency-dependent sound absorption coefficient are successfully compared with permeability and impedance-tube measurements. The authors' results indicate the important effect of fiber orientation on flow properties associated with the different physical properties of fibrous materials. A direct link is provided between three-dimensional microstructure and the sound absorbing properties of non-woven fibrous materials, without the need for any empirical formulae or fitting parameters.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Luu

Perrot

Monchiet

et al. 2017

The Journal of the Acoustical Society of America

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“…5(a). Indeed, it is well known that frame compression results in an increase of airflow resistivity and tortuosity since the various struts and remaining membranes are brought nearer from each other [24,25]. These results show that the proposed reticulation method can be used to tune the resistive behavior of closed-cell foams depending on the final application of the foam material.…”

Section: Influence Of Shock Strengthmentioning

confidence: 71%

Using shock waves to improve the sound absorbing efficiency of closed-cell foams

Doutres¹,

Atalla²,

Brouillette³

et al. 2014

Applied Acoustics

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Producing closed-cell foams is generally cheaper and simpler than open-cell foams.However, the acoustic and filtration efficiency of closed-cell foam materials is generally poor because it is very difficult for fluid or acoustic waves to penetrate into the material. A new method using shock waves to remove the membranes closing the cell pores (known as reticulation) and thus to improve the acoustic and filtration behavior of closed-cell foam material is presented. Various shock treatments have been carried out on polyurethane and polyimide foams and the following conclusions were drawn: (1) reticulation efficiency increased and thus the airflow resistivity and tortuosity decreased when increasing the amplitude of the shock treatment; (2) the rigidity of the foam is decreased; (3) the process is reliable and repeatable and (4) obtained acoustic performance is comparable to classical thermal reticulation.

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“…One can see that the resistivity for a given density is highest in the X direction and the resistivities in the Y and Z directions are equal within the scatter of the data. In the paper by Castagnede et al, 9 it was assumed that the resistivity is proportional to the mass density, but the direct measurement in Fig. 2 shows this is not the case.…”

Section: Results Of Measurementsmentioning

confidence: 99%

Measured anisotropic air flow resistivity and sound attenuation of glass wool

Tarnow

2002

The Journal of the Acoustical Society of America

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The air flow resistivity of glass wool has been measured in different directions. The glass wool was delivered from the manufacturer as slabs measuring 100ϫ600ϫ900 mm 3 , where the surface 600ϫ900 mm 2 was parallel with the conveyor belt used in the manufacturing. Directions in the glass wool are described by a coordinate system with the X axis perpendicular to the conveyor belt, the Z axis in the direction the conveyor belt moves, and the Y axis perpendicular to the two other axes. It was found that the resistivities in the Y and Z directions were equal in all cases. For density 14 kg/m 3 the mean resistivity in the X direction was 5.88 kPa s m Ϫ2 and in the Y direction 2.94 kPa s m Ϫ2. For density 30 kg/m 3 the mean resistivity in the X direction was 15.5 kPa s m Ϫ2 and in the Y direction 7.75 kPa s m Ϫ2. A formula for prediction of resistivity for other densities is given. By comparing measured values of sound attenuation with results calculated from resistivity data, it is demonstrated that the measured attenuation can be predicted in a simple manner.

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Effects of compression on the sound absorption of fibrous materials

Cited by 87 publications

References 9 publications

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Three-dimensional reconstruction of a random fibrous medium: Geometry, transport, and sound absorbing properties

Using shock waves to improve the sound absorbing efficiency of closed-cell foams

Measured anisotropic air flow resistivity and sound attenuation of glass wool

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