Sound waves in foams

Kann, K. B.

doi:10.1016/j.colsurfa.2005.04.010

Cited by 27 publications

(32 citation statements)

References 3 publications

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“…A related subject is the propagation of acoustic waves through foams, which has been surprisingly considered only rather recently (Moxon, Torrance & Richardson, 1988, Mujica & Fauve, 2002, Kann, 2005, Pierre et al, 2013, Pierre, Dollet & Leroy, 2014. Most experimental studies (Mujica & Fauve, 2002, Pierre et al, 2013 report low values of the speed of sound (of the order of 50 m/s), in agreement with mean field models that predict the speed of sound from the average density and compressibility of the foam (Wood, 1944).…”

Section: Introductionsupporting

confidence: 50%

“…Most experimental studies (Mujica & Fauve, 2002, Pierre et al, 2013 report low values of the speed of sound (of the order of 50 m/s), in agreement with mean field models that predict the speed of sound from the average density and compressibility of the foam (Wood, 1944). However, much higher sound velocities (of the order of 200 m/s) have also been measured (Moxon, Torrance & Richardson, 1988), and dedicated models (Kann, 2005) have been proposed, describing the sound propagation as occurring in the gas phase only, except for Figure 1. (a): Experimental setup (not to scale).…”

Section: Introductionmentioning

confidence: 99%

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Coupled vibrations of a meniscus and liquid films

2015

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We investigate the vibration properties of a circular horizontal film that is bounded by a meniscus (or Plateau border) and suspended between two catenary films. The suspending films act as capillary springs, and the system is thus free to oscillate around its equilibrium position. We study its free and forced oscillations. In our experiments, we track simultaneously the positions of the Plateau border and the film. The model that we present predicts the eigenfrequency of the system and its resonance characteristics (in forced oscillations). In particular, we show that the dynamics of both the Plateau border and the film have to be taken into account in order to provide an accurate prediction of the oscillation frequency.

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Section: Introductionsupporting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Coupled vibrations of a meniscus and liquid films

2015

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“…/ 0°° a'2n(a')dar (11) In this definition, n{a') is the distribution function of the film radii a', assumed to follow a log-normal distribution like the bubble radii, with a polydispersity ef , and U is defined as…”

Section: T(qa) A'2n(a')h{qa')da'mentioning

confidence: 99%

“…The key point is to understand how a soft liquid skeleton vibrates and eventually how such vibrations modify the propagation of sound from the one in a pure gas. Implementing earlier works [9][10][11], significant experimental and theoretical progress have recently been reported on foam acoustics [12][13][14][15][16][17][18]. Some of these were obtained with experimental setup based on ultrasonic transducers [ 14,15,18], Other experiments with impedance tube allowed to broaden the range of investigated frequencies [12,16].…”

Section: Introductionmentioning

confidence: 96%

Sound propagation in liquid foams: Unraveling the balance between physical and chemical parameters

et al. 2015

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We present experimental results on the propagation of an ultrasonic wave (40 kHz) in liquid foams, as a function of the foam physical and chemical parameters. We have first implemented an original setup, using transducers in a transmission configuration. The foam coarsening was used to vary the bubble size (remaining in the submillimeter range), and we have made foams with various chemical formulations, to investigate the role of the chemicals at the bubble interfaces or in bulk. The results are compared with recently published theoretical works, and good agreements are found. In particular, for all the foams, we have evidenced two asymptotic limits, at small and large bubble size, connected by a nontrivial resonant behavior, associated to an effective negative density. These qualitative features are robust whatever the chemical formulation; we discuss the observed differences between the samples, in relation to the interfacial and bulk viscoelasticity. These results demonstrate the rich and complex acoustic behavior of foams. While the bubble size remain here always smaller than the sound wavelength, it turns out that one must go well beyond mean-field modeling to describe the foam acoustic properties.

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“…Although these types of models are generally thought to adequately describe the mechanical properties of porous materials at a macro-scale, they do not address the micro-scale level, which is important in material design for energy absorption, wave propagation considerations, and to understand the effect of different morphologies on material response [6]. Several researchers have identified unique properties in porous materials such as a reduced wave speed [7][8][9] and attenuation of stress waves [10][11][12][13] when analyzing the deformation mechanics of both metallic and polymeric foams and at the pore level, where the current study considered a closed-cell polymeric foam.…”

Section: Introductionmentioning

confidence: 99%

Deformation Mechanics of a Non-Linear Hyper-Viscoelastic Porous Material, Part II: Porous Material Micro-Scale Model

Salisbury

Cronin

Lien

2015

J. dynamic behavior mater.

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Foam materials are widely used for energy absorbing applications, and are often addressed in a modeling environment at a macroscopic or continuum level by measuring the mechanical properties, which may be size dependent, and implementing the properties in a continuum-level constitutive model. However, foams are known to exhibit a characteristically low wave speed and an understanding of the deformation mechanics of foams at the micro-scale and dependence on morphology are essential to understand the performance of foam material in impact scenarios. In this study, experimental testing and finite element modeling were used to investigate a viscoelastic polychloroprene closed-cell foam at the cell level, subject to large deformation and high deformation rates. A numerical model was created with solid hexahedral elements and a repeated tetrakaidecahedron cell structure using measured foam cell size and wall thickness, and mechanical properties measured from non-porous polychloroprene. The finite element model predictions were evaluated using experimental compression tests on the foam material at high deformation rates. The enclosed nitrogen in the closed cell foam was modeled using an Arbitrary Lagrange-Eulerian method so that this contribution could be included or removed, and demonstrated the significant effect of the enclosed gas on the mechanical response of the foam. The foam cell dimensions were varied to investigate morphological factors including cell size, cell aspect ratio and cell wall thickness.Increasing wall thickness, decreasing cell size and decreasing the cell aspect ratio resulted in increased material stiffness, with wall thickness having the most significant effect. Investigation of the wave transmission speed demonstrated a low value compared to the constituent materials, which was explained by the path of the stress wave through the foam structure and wave reflections within the cells, attenuating the stress wave. The consequence of this low wave speed was non-uniform deformation of the foam sample demonstrating that the measured mechanical properties of porous foams depend on the sample thickness, an important consideration for foam material testing and characterization.

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Sound waves in foams

Cited by 27 publications

References 3 publications

Coupled vibrations of a meniscus and liquid films

Coupled vibrations of a meniscus and liquid films

Sound propagation in liquid foams: Unraveling the balance between physical and chemical parameters

Deformation Mechanics of a Non-Linear Hyper-Viscoelastic Porous Material, Part II: Porous Material Micro-Scale Model

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