Flow resistance information for acoustical design

Bies, David A.; Hansen, Colin H.

doi:10.1016/0003-682x(80)90002-x

Cited by 212 publications

(99 citation statements)

References 4 publications

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“…The vector x here is the design variable vector which is composed of the parameters with unknown values and need to be determined with the help of minimisation procedure Eq. (24). The sum in Eq.…”

Section: Optimisation Methods For Parameter Inversionmentioning

confidence: 99%

“…There are several models that can be used to link the fibre diameter d f , and material density ρ f , with the flow resistivity, σ. 24,25 However, a better model to enable this link is the Carman-Kozeny model for the permeability of porous media, 26 which was introduced in the 1930s. Unlike some other empirical models, which can be used to predict the flow resistivity of fibre, the Carman-Kozen model is derived from Poiseuille's equation for laminar flow and presents a theoretical links between the flow resistivity, fibre diameter, and bulk material density.…”

Section: Reticulated Foams and Fibrous Materialsmentioning

confidence: 99%

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A Review of Acoustical Methods for Porous Material Characterisation

Horoshenkov¹

2017

IJAV

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The purpose of this paper is to present and discuss a range of in-situ and laboratory methods can be used to measure the morphological characteristics of porous materials. In the case of foams and granular media used for noise control applications, the most common of these characteristics are pore size and its distribution, porosity, and pore connectivity. In the case of fibrous media, the most useful non-acoustical characteristics are the fibre size and packing density. In the case of outdoor surfaces such as gravel, sandy soils, and agricultural land, which can be partly saturated with water, it is of direct interest to measure the degree of water saturation hydraulic permeability and pore size gradient. In the case of materials with good physiochemical properties, it is of interest to determine their internal pore surface area, porosity, and pore size scales. In this paper, the existing and newly emerging acoustic characterisation methods are discussed in terms of their complexity, accuracy, and sample requirements. The application of these methods relate to traditional needs to measure and predict the in-situ performance of noise control elements and outdoor surfaces, to ensure the quality control during material manufacturing process and to be able to measure non-invasively the micro-and nano-structure of porous media which is used in catalytic filters, electric capacitors and for gas storage. Parts of this paper were presented at the 22nd International Congress on Sound and Vibration in Florence.

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Section: Optimisation Methods For Parameter Inversionmentioning

confidence: 99%

Section: Reticulated Foams and Fibrous Materialsmentioning

confidence: 99%

A Review of Acoustical Methods for Porous Material Characterisation

Horoshenkov¹

2017

IJAV

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“…First, empirical methods have been developed from the analysis of the exact nature of the microstructure and the measurement of the acoustic performance. [2][3][4][5][6] These models, mainly developed for fibers, give an estimation of the airflow resistivity r from the bulk density of the fibrous material q 1 and the fiber diameter d. It is found that the relation between these three parameters depends on the type of material (glass wool, polyester fibers…) under investigation; which is characteristic of empirical approaches, but can nevertheless be used to optimize the fabrication process of the considered porous material.…”

Section: Introductionmentioning

confidence: 99%

Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams

Doutres¹,

Atalla²,

Dong³

2011

Journal of Applied Physics

133

134

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The present paper proposes to investigate the links between the microstructure of polyurethane foams and their sound absorbing efficiency, and more specifically the effect of membranes closing the cells. This study is based on the complete characterization of 15 polyurethane foam with various cell sizes and reticulation rates (i.e., open pore content): (i) characterization of the microstructure properties (cell size C s , strut thickness t, reticulation rate R w …) from SEM pictures, (ii) characterization of nonacoustic parameters (porosity U, airflow resistivity r, tortuosity a 1 …) from direct and indirect methods. Existing analytical links between microstructure properties and nonacoustic parameters are first applied to fully reticulated materials. Then, they are improved empirically to account for the presence of the closed pore content. The proposed expressions associated to the Johnson-Champoux-Allard porous model allow a good estimation of the sound absorbing behavior of all polyurethane foams, fully reticulated or not. This paper also demonstrates the important effect of the presence of cell membranes: increase of the airflow resistivity, tortuosity, and the ratio between the thermal and viscous characteristic lengths while decreasing these two characteristic lengths. Thus, the sound absorption efficiency at low frequencies is improved but can be worsened in some higher frequency bands.

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“…The empirical model is a good and fast approximation to the theoretical calculations because the model needs only one input parameter, the airflow resistivity. Bies and Hansen (1980) extended the lower and upper frequency ranges of validity of this model. Further updates and improvements were recommended by Miki (1990a, b).…”

Section: Empirical Modelsmentioning

confidence: 88%

Recent Advances in the Sound Insulation Properties of Bio-based Materials

Zhu¹,

Kim²,

Wang³

et al. 2013

BioResources

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Many bio-based materials, which have lower environmental impact than traditional synthetic materials, show good sound absorbing and sound insulation performances. This review highlights progress in sound transmission properties of bio-based materials and provides a comprehensive account of various multiporous bio-based materials and multilayered structures used in sound absorption and insulation products. Furthermore, principal models of sound transmission are discussed in order to aid in an understanding of sound transmission properties of bio-based materials. In addition, the review presents discussions on the composite structure optimization and future research in using co-extruded wood plastic composite for sound insulation control. This review contributes to the body of knowledge on the sound transmission properties of bio-based materials, provides a better understanding of the models of some multiporous bio-based materials and multilayered structures, and contributes to the wider adoption of bio-based materials as sound absorbers.

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Flow resistance information for acoustical design

Cited by 212 publications

References 4 publications

A Review of Acoustical Methods for Porous Material Characterisation

A Review of Acoustical Methods for Porous Material Characterisation

Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams

Recent Advances in the Sound Insulation Properties of Bio-based Materials

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