A self-assembled metamaterial for Lamb waves

Khanolkar, Amey; Wallen, Samuel P.; Ghanem, Maroun Abi; Jenks, Jeremiah W.; Vogel, Nicolas; Boechler, Nicholas

doi:10.1063/1.4928564

Cited by 44 publications

(40 citation statements)

References 63 publications

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“…Variations in the contact resonance frequency have previously been observed and hypothesized to be caused to factors that stem from variations in the sample preparation procedure [33]. In addition, the formation of solid bridges near the contact due to impurities in the colloidal solution and capillary effects have also been suggested as a possible cause of stiffer contacts [34].…”

Section: Bead-side Imagingmentioning

confidence: 99%

Time-domain imaging of gigahertz surface waves on an acoustic metamaterial

et al. 2018

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We extend time-domain imaging in acoustic metamaterials to gigahertz frequencies. Using a sample consisting of a regular array of ∼1 μm diameter silica microspheres forming a two-dimensional triangular lattice on a substrate, we implement an ultrafast technique to probe surface acoustic wave propagation inside the metamaterial area and incident on the metamaterial from a region containing no microspheres, which reveals the acoustic metamaterial dispersion, the presence of band gaps and the acoustic transmission properties of the interface. A theoretical model of this locally resonant metamaterial based on normal and shear-rotational resonances of the spheres fits the data well. Using this model, we show analytically how the sphere elastic coupling parameters influence the gap widths.

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Section: Bead-side Imagingmentioning

confidence: 99%

Time-domain imaging of gigahertz surface waves on an acoustic metamaterial

et al. 2018

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“…A new frontier was opened by laser-based experiments on 2D selfassembled monolayers of micron-sized particles on a solid substrate [7][8][9][10][11]. These experiments revealed the crucial role of adhesion, which is negligible for large particles but becomes an important factor in determining the contact stiffness at the microscale.…”

Section: Introductionmentioning

confidence: 99%

Vibrational dynamics of a two-dimensional microgranular crystal

et al. 2017

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We study the dynamics of an ordered hexagonal monolayer of polystyrene microspheres adhered to a glass substrate coated with a thin aluminum layer. A laser-induced transient grating technique is employed to generate and detect three types of acoustic modes across the entire Brillouin zone in the −K direction: low-frequency contact-based modes of the granular monolayer, high-frequency modes originating from spheroidal vibrations of the microspheres, and surface Rayleigh waves. The dispersion relation of contact-based and spheroidal modes indicates that they are collective modes of the microgranular crystal controlled by particle-particle contacts. We observe a spheroidal resonance splitting caused by the symmetry breaking due to the substrate, as well as an avoided crossing between the Rayleigh and spheroidal modes. The measurements are found to be in agreement with our analytical model.

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“…The equivalent one-dimensional coupled oscillator system reduces to a chain of spheres of mass m connected to one another by springs of stiffness G e , and connected to the substrate by a spring of stiffness K N . The mass of the sphere is calculated using the density ρ = 1060 kg/m 3 of polystyrene [44] . Since our measurements are sensitive to the out-of-plane direction only and we excite primarily longitudinal plane waves, we neglect adhesive contact forces in the transverse direction between neighboring spheres within the same layer.…”

Section: Resultsmentioning

confidence: 99%

Longitudinal eigenvibration of multilayer colloidal crystals and the effect of nanoscale contact bridges

et al. 2019

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Longitudinal contact-based vibrations of colloidal crystals with a controlled layer thickness are studied. These crystals consist of 390 nm diameter polystyrene spheres arranged into close packed, ordered lattices with a thickness of one to twelve layers. Using laser ultrasonics, eigenmodes of the crystals that have out-of-plane motion are excited. The particle-substrate and effective interlayer contact stiffnesses in the colloidal crystals are extracted using a discrete, coupled oscillator model. Extracted stiffnesses are correlated with scanning electron microscope images of the contacts and atomic force microscope characterization of the substrate surface topography after removal of the spheres. Solid bridges of nanometric thickness 1 arXiv:1810.03771v1 [cond-mat.mes-hall] 9 Oct 2018 are found to drastically alter the stiffness of the contacts, and their presence is found to be dependent on the self-assembly process. Measurements of the eigenmode quality factors suggest that energy leakage into the substrate plays a role for low frequency modes but is overcome by disorder-or material-induced losses at higher frequencies. These findings help further the understanding of the contact mechanics, and the effects of disorder in threedimensional micro-and nano-particulate systems, and open new avenues to engineer new types of micro-and nanostructured materials with wave tailoring functionalities via control of the adhesive contact properties.

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A self-assembled metamaterial for Lamb waves

Cited by 44 publications

References 63 publications

Time-domain imaging of gigahertz surface waves on an acoustic metamaterial

Time-domain imaging of gigahertz surface waves on an acoustic metamaterial

Vibrational dynamics of a two-dimensional microgranular crystal

Longitudinal eigenvibration of multilayer colloidal crystals and the effect of nanoscale contact bridges

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