Tuning sound with soft dielectrics

Bortot, Eliana; Gal, Shmuel

doi:10.1088/1361-665x/aa6387

Cited by 36 publications

(19 citation statements)

References 56 publications

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“…On the other hand, auxetic materials present very interesting features 17 – 21 originating from negative Poisson’s ratio, such as increased shear modulus, indentation resistance, fracture toughness, energy absorption, porosity/permeability variation with strain and synclastic curvature, which also depend on the topology of the unit cell. It is therefore very interesting to study the combination of such properties 22 – 25 to obtain a metamaterial endowed with controllable phononic bandgaps 26 , 27 to be tailored, degraded or enhanced during its functioning. Several tunable PnCs, 28 , 29 which take advantage of different materials or properties combined together, are available.…”

Section: Introductionmentioning

confidence: 99%

3D auxetic single material periodic structure with ultra-wide tunable bandgap

Dalessandro

Zega

Ardito

et al. 2018

Sci Rep

118

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The design and the combination of innovative metamaterials are attracting increasing interest in the scientific community because of their unique properties that go beyond the ones of natural materials. In particular, auxetic materials and phononic crystals are widely studied for their negative Poisson’s ratio and their bandgap opening properties, respectively. In this work, auxeticity and phononic crystals bandgap properties are properly combined to obtain a single phase periodic structure with a tridimensional wide tunable bandgap. When an external tensile load is applied to the structure, the auxetic unit cells change their configurations by exploiting the negative Poisson’s ratio and this results in the tuning, either hardening or softening, of the frequencies of the modes limiting the 3D bandgap. Moreover, the expansion of the unit cell in all the directions, due to the auxeticity property, guarantees a fully 3D bandgap tunability of the proposed structure. Numerical simulations and analytical models are proposed to prove the claimed properties. The first experimental evidence of the tunability of a wide 3D bandgap is then shown thanks to the fabrication of a prototype by means of additive manufacturing.

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Section: Introductionmentioning

confidence: 99%

3D auxetic single material periodic structure with ultra-wide tunable bandgap

Dalessandro

Zega

Ardito

et al. 2018

Sci Rep

118

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“…where Most of the existing researches on soft DE PCs take no account of material compressibility [29][30][31][32][33][34].…”

Section: Nonlinear Deformation Of a Homogeneous De Cylindermentioning

confidence: 99%

“…Shmuel and Pernas-Salomón [31] proposed an effective way to realize mode localization in DE films via electrostatically controlled aperiodicity. Noticing that the analysis in Yang and Chen [24] is not fully nonlinear, Bortot and Shmuel [32] performed a re-examination and found that the snap-through instability resulting from geometrical and material nonlinearities can be harnessed to achieve sharp transitions in the acoustic BG. Galich and Rudykh [33] re-examined the problem that was studied by Shmuel and deBotton [30] and arrived at a different conclusion that shear waves propagating perpendicular to the layers in ideal neo-Hookean DE laminates are not affected by the electric field directly.…”

Section: Introductionmentioning

confidence: 99%

Tuning Elastic Waves in Soft Phononic Crystal Cylinders Via Large Deformation and Electromechanical Coupling

Zhou

Bao

et al. 2018

Journal of Applied Mechanics

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Soft electroactive materials can undergo large deformation subjected to either mechanical or electrical stimulus, and hence, they can be excellent candidates for designing extremely flexible and adaptive structures and devices. This paper proposes a simple one-dimensional soft phononic crystal (PC) cylinder made of dielectric elastomer (DE) to show how large deformation and electric field can be used jointly to tune the longitudinal waves propagating in the PC. A series of soft electrodes, which are mechanically negligible, are placed periodically along the DE cylinder, and hence, the material can be regarded as uniform in the undeformed state. This is also the case for the uniformly prestretched state induced by a static axial force only. The effective periodicity of the structure is then achieved through two loading paths, i.e., by maintaining the longitudinal stretch and applying an electric voltage over any two neighboring electrodes or by holding the axial force and applying the voltage. All physical field variables for both configurations can be determined exactly based on the nonlinear theory of electroelasticity. An infinitesimal wave motion is further superimposed on the predeformed configurations, and the corresponding dispersion equations are derived analytically by invoking the linearized theory for incremental motions. Numerical examples are finally considered to show the tunability of wave propagation behavior in the soft PC cylinder. The outstanding performance regarding the band gap (BG) property of the proposed soft dielectric PC is clearly demonstrated by comparing with the conventional design adopting the hard piezoelectric material. One particular point that should be emphasized is that soft dielectric PCs are susceptible to various kinds of failure (buckling, electromechanical instability (EMI), electric breakdown (EB), etc.), imposing corresponding limits on the external stimuli. This has been carefully examined for the present soft PC cylinder such that the applied electric voltage is always assumed to be less than the critical voltage except for one case, in which we illustrate that the snap-through instability of the axially free PC cylinder made of a generalized Gent material may be used to efficiently trigger a sharp transition in the BGs.

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“…The snap-through instability of SEA balloons was used by Rudykh et al (2012) to design electrostatically controllable actuators and micropumps. Recently, the snap-through instability of phononic crystals made of SEA cylindrical structures was also utilized to realize sharp transitions in the bandgap width and position (Bortot and Shmuel, 2017;Wu et al, 2018c). As a result, another goal of this paper is focused on how the resonant frequency of a SEA spherical balloon is influenced by the phenonenon of snap-through instability.…”

Section: Introductionmentioning

confidence: 99%

Electrostatically tunable small-amplitude free vibrations of pressurized electro-active spherical balloons

Mao

Carrera

et al. 2019

International Journal of Non-Linear Mechanics

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Designing tunable resonators is of practical importance in active/adaptive sound generation, noise control, vibration isolation and damping. In this paper, we propose to exploit the biasing fields (induced by internal pressure and radial electric voltage) to tune the threedimensional and small-amplitude free vibration of a thick-walled soft electro-active (SEA) spherical balloon. The incompressible isotropic SEA balloon is characterized by both neo-Hookean and Gent ideal dielectric models. The equations governing small-amplitude vibrations under inhomogeneous biasing fields can be linearized and solved in spherical coordinates using the state-space formalism, which establishes two separate transfer relations correlating the state vectors at the inner surface with those at the outer surface of the SEA balloon. By imposing the mechanical and electric boundary conditions, two separate analytical frequency equations are derived, which characterize two independent classes of vibration for torsional and spheroidal modes, respectively. Numerical examples are finally conducted to validate the theoretical derivation as well as to investigate the effects of both radial electric voltage and internal pressure on the resonant frequency of the SEA balloon. The reported analytical solution is truly and fully three-dimensional, covering from the purely radial breathing mode to torsional mode to any general spheroidal mode, and hence provides a more accurate prediction of the vibration characteristics of tunable resonant devices that incorporate the SEA spherical balloon as the tuning element.

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Tuning sound with soft dielectrics

Cited by 36 publications

References 56 publications

3D auxetic single material periodic structure with ultra-wide tunable bandgap

3D auxetic single material periodic structure with ultra-wide tunable bandgap

Tuning Elastic Waves in Soft Phononic Crystal Cylinders Via Large Deformation and Electromechanical Coupling

Electrostatically tunable small-amplitude free vibrations of pressurized electro-active spherical balloons

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