Inversion Problems for Determining Physical Parameters of Porous Materials: Overview and Comparison Between Different Methods

Bonfiglio, Paolo; Pompoli, Francesco

doi:10.3813/aaa.918616

Cited by 64 publications

(50 citation statements)

References 15 publications

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“…Therefore, it becomes more common to use inverse methodologies to retrieve the desired characteristic parameters [9]. The work presented in this paper is based on the inversion of the flow resistivity alone from the acoustic absorption coefficient data obtained from a 2-microphone impedance tube experiment.…”

Section: Experimental Methodologymentioning

confidence: 99%

An application of Kozeny–Carman flow resistivity model to predict the acoustical properties of polyester fibre

2016

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a b s t r a c tModelling of the acoustical properties of polyester fibre materials is usually based on variations of the Bies and Hansen empirical model [1], which allows the calculation of the air flow resistivity of a porous material. The flow resistivity is the key non-acoustical parameter which determines the ability of this kind of materials to absorb sound. The main scope of this work is to illustrate that an alternative theoretical model based on the Kozeny-Carman equation can be used to predict more accurately the flow resistivity from the fibre diameter and bulk material density data. In this paper the flow resistivity is retrieved from the acoustic absorption coefficient data for polyester fibre samples of different densities and fibre diameters. These data agree closely with the flow resistivity predicted with the proposed Kozeny-Carman model.

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Section: Experimental Methodologymentioning

confidence: 99%

An application of Kozeny–Carman flow resistivity model to predict the acoustical properties of polyester fibre

2016

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“…Regarding the fluid phase experimental measurements of airflow resistivity, open porosity, and tortuosity have been carried out. Viscous and thermal characteristic lengths have been determined by using an inverse procedure starting from minimization of surface impedance with respect to the Johnson-Champoux-Allard's model [11].…”

Section: Prediction Of Transmission Loss Performancementioning

confidence: 99%

Dynamic mechanical response of foams for noise control

Briatico‐Vangosa¹,

Benanti²,

Andena³

et al. 2016

AIP Conference Proceedings

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Abstract. In this work, the viscoelastic behavior of open cell polyurethane foams used in noise control applications is investigated through dynamic mechanical analysis in compression. Several levels of static strains superimposed on a small dynamic one were considered in order to assess the effect of material non-linearity on the mechanical response.Further, a wide range of frequencies and temperatures was explored. For each static strain a different master curve for conservative component of complex modulus, E', could be determined. Interestingly, the loss factor was the same at all static strains, indicating that the relative contribution of energy dissipation and conservation is unaffected by the static strain. Moreover, shift factors (and thus the bulk material relaxation times) turned out to be independent on static strain level. These results suggest that the non-linearity of the foam is linked to the change in foam structure with strain rather than to a non-linear behavior of the viscoelastic constituent material. The acoustic performance of the considered materials was modelled for a case study with two approaches: i) standard simulations performed taking a single valued complex modulus, measured at 50Hz and room temperature or ii) simulations taking into account the complex modulus frequency dependence obtained from the master curves. The transmission loss prediction obtained in the second case is in better agreement with experiments, especially at high frequencies.

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“…These acoustical parameters may be deduced by inverting the acoustic measurement data. These data can be obtained by measuring the sound fields reflected by rigid porous materials, either in a standing wave tube 9,10 or in a near-grazing propagation condition. [11][12][13] Allard and his co-workers [11][12][13][14][15] conducted a series of studies exploring the propagation of sound above a hardbacked porous layer.…”

Section: Introductionmentioning

confidence: 99%

Sound penetration into a hard-backed rigid porous layer: Theory and experiments

Tao¹,

Tong²,

Li³

2014

The Journal of the Acoustical Society of America

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This study examines the sound field within a hard-backed rigid porous medium due to an airborne source. The total sound field can be approximated by two terms: A transmitted wave component arriving at the receiver directly through the porous interface, and a second transmitted wave component reflected from the rigid backing plane before reaching the receiver. These two components can be expressed in an integral form that is amenable to further analyses. A standard saddle path method is applied to evaluate the integral analytically, leading to a uniform asymptotic solution that allows the prediction of the sound field within the rigid porous medium. The validity of the asymptotic formula is verified by comparison with the numerical results computed by a more accurate wave-based numerical scheme. The asymptotic solution is shown to provide a convenient means of rapid and accurate computations of sound field within the rigid porous medium. The accuracy of the numerical solutions is further confirmed by comparison with indoor experimental results. The measurement data and theoretical predictions suggest that when the receiver is located near the bottom of the hard-backed layer, the reflection of the refracted wave gives rise to a significant contribution to the total sound field.

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Inversion Problems for Determining Physical Parameters of Porous Materials: Overview and Comparison Between Different Methods

Cited by 64 publications

References 15 publications

An application of Kozeny–Carman flow resistivity model to predict the acoustical properties of polyester fibre

An application of Kozeny–Carman flow resistivity model to predict the acoustical properties of polyester fibre

Dynamic mechanical response of foams for noise control

Sound penetration into a hard-backed rigid porous layer: Theory and experiments

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