Deeply subwavelength giant monopole elastodynamic metacluster resonators

Cotterill, Philip A.; Nigro, David; Parnell, William J.

doi:10.1098/rspa.2022.0026

Cited by 4 publications

(3 citation statements)

References 33 publications

(49 reference statements)

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“…We hypothesize that any material filled with monopole scatterers would, on average, respond like a homogeneous material. Monopole scatterers are a good approximation for many types of resonant particles [31]. Figure 9 compares the results for the monopole scattering approximation with MC results for sound-soft particles, which does not assume the particles scatter like monopoles.…”

Section: Discussionmentioning

confidence: 99%

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Effective T-matrix of a cylinder filled with a random two-dimensional particulate

Napal,

Piva,

Gower

2024

Proc. R. Soc. A.

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When a wave, such as sound or light, scatters within a densely packed particulate, it can be rescattered many times between the particles, which is called multiple scattering. Multiple scattering can be unavoidable when trying to use sound waves to measure a dense particulate, such as a composite with reinforcing fibres. Here, we solve from first principles multiple scattering of scalar waves, including acoustic, for any frequency from a set of two-dimensional particles confined in a circular area. This case has not been solved yet, and its solution is important to perform numerical validation, as particles within a cylinder require only a finite number of particles to perform direct numerical simulations. The method we use involves ensemble averaging over particle configurations, which leads us to deduce an effective T-matrix for the whole cylinder, which can be used to easily describe the scattering from any incident wave. In the specific case when the particles are monopole scatterers, the expression of this effective T-matrix simplifies and reduces to the T-matrix of a homogeneous cylinder with an effective wavenumber k ⋆ . To validate our theoretical predictions, we develop an efficient Monte Carlo method and conclude that our theoretical predictions are highly accurate for a broad range of frequencies.

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Section: Discussionmentioning

confidence: 99%

“…For example, in acoustics void-like, particles are approximately monopoles for a broad frequency range, see the Dirichlet case in figure 2. In elasticity, particles become approximately monopole when the bulk modulus is much greater than the shear modulus [31]. Other cases include resonators such as a split ring resonator [32].…”

Section: (E) Effective Propertiesmentioning

confidence: 99%

Effective T-matrix of a cylinder filled with a random two-dimensional particulate

Napal,

Piva,

Gower

2024

Proc. R. Soc. A.

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“…Mechanical metamaterials are artificial composite structures with exotic properties which cannot be found from traditional systems. According to the special units, people can design the structures with extraordinary elastic wave properties [1][2][3][4]. The mechanical metamaterials can show their extensive engineering applications, e.g.…”

Section: Introductionmentioning

confidence: 99%

Non-Abelian mechanics of elastic waves in Kagome metamaterials with internal microstructures

Yang

Wang

2023

Proc. R. Soc. A.

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In this work, the duality of mechanical Kagome lattices with internal microstructures is studied and its non-Abelian characteristics of wave packet evolution are discussed. Based on Bloch's theorem, the dynamical and duality matrices are obtained during elastic wave propagation. By regulating the twisting angles of the Kagome lattices and internal microstructures, global twofold degeneracy and unequal Berry phase can be obtained. A fourfold degeneracy appears at Γ point when the mechanical metamaterial is subjected to a special twisting state. Numerical calculations of non-Abelian mechanics and duality are performed, in which band structures with special twisting angles are the same. In addition, the solution of the Wilson operator is derived by the elastic wave equation and gauge transformation, which has non-exchangeable product and leads to the non-Abelian Berry curvature. If the time-reversal symmetry is broken, non-commutative elastic wave responses can be generated. The generalized polarization and wave propagation become different when the acting sequences of external forces are exchanged.

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Enhanced elastodynamic resonance via co-dipole metaclusters

Touboul

Cotterill

Nigro

et al. 2022

Applied Physics Letters

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Metamaterials exploit sub-wavelength microstructures to yield novel macroscopic material properties. Recently, the notion of a metacluster has emerged, which is a collection of resonators that interact in order to modify and possibly enhance the resonance. They can also be employed to modify and tune the far-field scattered response. This is particularly important with regard to metamaterial design. In the context of elastodynamics, Cotterill et al. [Proc. R. Soc. A 478(2263), 20220026 (2022)] considered the case of void metaclusters, thus permitting the modification of the so-called giant monopole resonance in elastodynamics. Here, we consider one of the original resonant configurations of metamaterial science in Liu et al. [Science 289, 1734 (2000)]; this structure consists of coated cylinders of circular cross section and gives rise to a strong dipole resonance for sufficiently soft coatings. We consider the nature of the interaction of two such identical resonators in close proximity, which we term the co-dipole metacluster. We show that, contrary to the giant monopole case, the frequency at which the resonance occurs is unchanged as compared to a single resonator. The amplitude of the resonance itself is enhanced significantly, however, by up to 5.7 times the enhancement observed when considering two non-interacting resonators. Furthermore, although the nature of the resonance remains dominated by a dipole response, both the enhancement and the far-field scattered response are now significantly affected by the incidence angle, in contrast to the single resonator.

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Deeply subwavelength giant monopole elastodynamic metacluster resonators

Cited by 4 publications

References 33 publications

Effective T-matrix of a cylinder filled with a random two-dimensional particulate

Effective T-matrix of a cylinder filled with a random two-dimensional particulate

Non-Abelian mechanics of elastic waves in Kagome metamaterials with internal microstructures

Enhanced elastodynamic resonance via co-dipole metaclusters

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