Guiding of elastic waves in a two-dimensional graded phononic crystal plate

Guo, Yuning; Hettich, Mike; Dekorsy, Thomas

doi:10.1088/1367-2630/aa5703

Cited by 12 publications

(5 citation statements)

References 28 publications

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“…Gradually varying the height of the pillars, resonant gradient index metalenses for flexural waves [142] and metasurfaces for converting surface Rayleigh waves to bulk shear waves [143] were proposed. The guiding of elastic waves with a graded radius of pillars in a phononic crystal plate has also been investigated [144]. (V) Phononic Graphene.…”

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confidence: 99%

Physics of surface vibrational resonances: pillared phononic crystals, metamaterials, and metasurfaces

et al. 2021

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The introduction of engineered resonance phenomena on surfaces has opened a new frontier in surface science and technology. Pillared phononic crystals, metamaterials, and metasurfaces are an emerging class of artificial structured materials, featuring surfaces, that consist of pillars-or branching substructures-standing on a substrate or a plate. A pillared phononic crystal exhibits Bragg band gaps while a pillared metamaterial may feature both Bragg gaps and local-resonance hybridization gaps. These two band-gap phenomena, along with other unique wave dispersion characteristics, have been exploited for a variety of applications spanning a range of length scales and covering multipe disciplines in applied physics and engineering. The placement of pillars on a semi-infinite surface has similarly provided new avenues for the control and manipulation of wave propagation, including Rayleigh and Love waves along the surface of substrates, as well as Lamb waves in plates-for frequencies ranging from Hz to several GHz. Even a finite placement of pillars along specific directions on a surface has been shown to offer unique functionality, such as steering a wavefront in the subwavelength regime. At the nanoscale, pillared membranes have been investigated and it was shown that atomic-scale resonances-stemming from the nanopillars-alter the fundamental nature of conductive thermal transport by reducing the group velocities and generating mode localization across the entire spectrum well into the THz regime. In this article, we first overview the history and development of pillared materials, then provide a detailed synopsis of a selection of key research topics that involve the utilization of pillars in different contexts. The following sections present a review of different configurations, properties, and 2 characteristics, namely: (i) fundamental vibrational and propagation properties of pillared plates; (ii) metamaterial phenomena in pillared plates including the opening of low and wide hybridization band gaps as well as super-resolution focusing; (iii) pillared metasurfaces and their wave steering functions;(iv) topologically protected phononic edge states in pillared plates; and (v) nanophononic metamaterials in the form of pillared membranes exhibiting exceptionally low in-plane thermal conductivity. Finally, we conclude by providing a short summary on the salient properties of pillared materials and structures and outlining some perspectives on the state of the field and its promise for further future development.

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confidence: 99%

Physics of surface vibrational resonances: pillared phononic crystals, metamaterials, and metasurfaces

et al. 2021

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“…For example, subwavelength waveguiding has been achieved by frequency upshifting of selected resonators located along a desired waveguide path 4,[7][8][9] , and topological effects have been observed in mechanical systems comprising hexagonal arrangements of different resonator types 10,11 . Similarly, rainbow trapping requires graded arrays of resonators with different characteristics, where each type of resonator distills a selected frequency from a broadband input signal [12][13][14][15][16][17][18][19] . Working with heterogeneous assemblies of resonators introduces an additional degree of freedom available for the metamaterial's design that results from the spatial arrangement of the different subsets of resonating units.…”

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Bandgap widening by disorder in rainbow metamaterials

Celli

Yousefzadeh

Daraio

et al. 2019

Applied Physics Letters

118

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Stubbed plates, i.e., thin elastic sheets endowed with pillar-like scatterers, display subwavelength, locallyresonant bandgaps that are controlled by both the intrinsic resonance properties of the pillars and by the relative stiffness of the pillars to the baseplate. In this work, we focus on the response of a thin and compliant plate featuring heterogeneous families of pillars. We demonstrate experimentally that both the spatial arrangement and the resonant frequencies of the pillars greatly influence the filtering characteristics of the system. We highlight that both spatially graded as well as random (disordered) arrangements of pillars result in macroscopic bandgap widening. We further report that the spectral range over which wave attenuation achieved with random arrangements is on average wider than the one observed while working with graded configurations. We explore the robustness of these findings against small changes in the structural and material properties of the plate and pillars.

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“…The ability to control the propagation of elastic waves through the utilization of metasurfaces (i.e., twodimensional plates) is important for wave guiding or vibration insulation of sensitive equipment 25,26 and the potential realization of meta-devices 14,27,28 . Metasurfaces decorated with arrays of pillars 29,30 have been utilized in many studies due to their simple geometry 19,[31][32][33][34][35][36][37][38][39][40][41][42] with applicability across multiple scales 27,43 . However, similar to most locally-resonant metamaterials, the resonance frequency of pillared-metasurfaces correlate strongly with the mass and volume of the pillar resonators.…”

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confidence: 99%

Enhancement of Deep-Subwavelength Band Gaps in Flat Spiral-Based Phononic Metamaterials Using the Trampoline Phenomena

Bilal

Foehr

Daraio

2020

Journal of Applied Mechanics

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Elastic and acoustic metamaterials can sculpt dispersion of waves through resonances. In turn, resonances can give rise to negative effective properties, usually localized around the resonance frequencies, which support band gaps at subwavelength frequencies (i.e., below the Bragg-scattering limit). However, the band gaps width correlates strongly with the resonators' mass and volume, which limits their functionality in applications. Trampoline phenomena have been numerically and experimentally shown to broaden the operational frequency ranges of two-dimensional, pillar-based metamaterials through perforation. In this work, we demonstrate trampoline phenomena in lightweight and planar lattices consisting of arrays of Archimedean spirals in unit cells. Spiral-based metamaterials have been shown to support different band gap opening mechanisms, namely, Bragg-scattering, local resonances and inertia amplification. Here, we numerically analyze and experimentally realize trampoline phenomena in planar metasurfaces for different lattice tessellations. Finally, we carry out a comparative study between trampoline pillars and spirals and show that trampoline spirals outperform the pillars in lightweight, compactness and operational bandwidth.

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Guiding of elastic waves in a two-dimensional graded phononic crystal plate

Cited by 12 publications

References 28 publications

Physics of surface vibrational resonances: pillared phononic crystals, metamaterials, and metasurfaces

Physics of surface vibrational resonances: pillared phononic crystals, metamaterials, and metasurfaces

Bandgap widening by disorder in rainbow metamaterials

Enhancement of Deep-Subwavelength Band Gaps in Flat Spiral-Based Phononic Metamaterials Using the Trampoline Phenomena

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