Soft silicone rubber in phononic structures: Correct elastic moduli

Still, Tim; Oudich, Mourad; Auernhammer, Günter K.; Vlassopoulos, D.; Djafari‐Rouhani, Bahram; Fytas, George; Sheng, Ping

doi:10.1103/physrevb.88.094102

Cited by 44 publications

(37 citation statements)

References 14 publications

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“…In the light of their highly porous structure, polymer foams are other possible candidates 10 . Soft polymers as silicone rubbers 11 can be made porous by using the polyHipes (for polymerizable High Internal Phase Emulsions) approach that consists in templating holes in the material using inverted water-in-oil emulsions [12][13][14] . In this paper, we show that such silicone polymers can indeed be made porous using this approach.…”

Section: Introductionmentioning

confidence: 99%

Soft Porous Silicone Rubbers as Key Elements for the Realization of Acoustic Metamaterials

Zimny

Merlin

et al. 2015

Langmuir

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In this work, macroporous materials made of polydimethylsiloxane, a soft silicone rubber, are prepared using UV polymerization with an emulsion-templating procedure. The porosity of the final materials can be precisely controlled by adjusting the volume of the dispersed phase. We show that the porous structure of the materials is the template of the droplets of the initial emulsions. Mechanical tests show that the materials Young's moduli decrease with the porosity of the materials. Acoustic measurements indicate that, in such a porous elastomeric matrix, the sound speed also decreases dramatically as soon as the porosity increases to attain values of as low as 80 m/s. The results are compared to earlier ones on silica aerogels and are interpreted within the framework of a simple theoretical approach. We show that the very low sound speed value is a consequence of the low value of the polymer shear modulus. This explains why such porous soft silicone rubbers are so efficient at playing the role of slow-soft resonators in acoustic metamaterials. Moreover, the fast rate of polymerization of such UV-curable fluid allows for a facile shaping of the final material as beads or rods in microfluidic devices.1.

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Section: Introductionmentioning

confidence: 99%

Soft Porous Silicone Rubbers as Key Elements for the Realization of Acoustic Metamaterials

Zimny

Merlin

et al. 2015

Langmuir

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“…The material parameters of the rubber membrane can be found in Ref. [49]. The unit cells are isolated from each other by the much higher rigidity of the aluminum grids as compared to the membranes.…”

Section: Decorated-membrane Systemmentioning

confidence: 99%

Homogenization scheme for acoustic metamaterials

Yang

et al. 2014

Phys. Rev. B

117

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We present a homogenization scheme for acoustic metamaterials that is based on reproducing the lowest orders of scattering amplitudes from a finite volume of metamaterials. This approach is noted to differ significantly from that of coherent potential approximation, which is based on adjusting the effective-medium parameters to minimize scatterings in the long-wavelength limit. With the aid of metamaterials' eigenstates, the effective parameters, such as mass density and elastic modulus can be obtained by matching the surface responses of a metamaterial's structural unit cell with a piece of homogenized material. From the Green's theorem applied to the exterior domain problem, matching the surface responses is noted to be the same as reproducing the scattering amplitudes. We verify our scheme by applying it to three different examples: a layered lattice, a two-dimensional hexagonal lattice, and a decorated-membrane system. It is shown that the predicted characteristics and wave fields agree almost exactly with numerical simulations and experiments and the scheme's validity is constrained by the number of dominant surface multipoles instead of the usual long-wavelength assumption. In particular, the validity extends to the full band in one dimension and to regimes near the boundaries of the Brillouin zone in two dimensions.

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“…The density and elastic constants of the two materials are reported in Table 2.3. In contrast to [34,17] where the velocities of sound in the polymer were assumed very low and especially unrealistic as concerns the longitudinal velocity, here we chose realistic values of longitudinal (1,000 m/s) and low transverse (20 m/s) velocities as reported in [50]. However, the physical conclusions which are much dependent upon the transverse velocity of the polymer will remain very similar to those presented in [34].…”

Section: Fluid-fluid Phononic Crystalmentioning

confidence: 87%

Fundamental Properties of Phononic Crystal

Pennec

Djafari‐Rouhani

2016

Phononic Crystals

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The control and manipulation of acoustic/elastic waves is a fundamental problem with many potential applications, especially in the field of information and communication technologies. For instance, confinement, guiding, and filtering phenomena at the scale of the wavelength are useful for signal processing, advanced nanoscale sensors, and acousto-optic on-chip devices; acoustic metamaterials, working in particular in the sub-wavelength regime can be used for efficient and broadband sound isolation as well as for imaging and super-resolution.Phononic crystals, which are artificial materials constituted by a periodic repetition of inclusions in a matrix, are proposed to achieve these objectives via the possibility of engineering their band structures. The elastic properties, shape, and arrangement of the scatterers modify strongly the propagation of the acoustic/elastic waves in the structure. The phononic band structure and dispersion curves can then be tailored with appropriate choices of materials, crystal lattices, and topology of inclusions.Similarly to any periodic structure, the propagation of acoustic waves in a phononic crystal is governed by the Bloch [1] or Floquet theorem from which one can derive the band structure in the corresponding Brillouin zone. The periodicity of the structures, that defines the Brillouin zone, may be in one (1D), two (2D), or three dimensions (3D). The propagation of acoustic waves in layered periodic materials or superlattices which are now being considered as 1D phononic crystals has been extensively studied [2] since the early paper of Rytov [3]. However, the

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Soft silicone rubber in phononic structures: Correct elastic moduli

Cited by 44 publications

References 14 publications

Soft Porous Silicone Rubbers as Key Elements for the Realization of Acoustic Metamaterials

Soft Porous Silicone Rubbers as Key Elements for the Realization of Acoustic Metamaterials

Homogenization scheme for acoustic metamaterials

Fundamental Properties of Phononic Crystal

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