Article

# Focusing ultrasound with an acoustic metamaterial network.

Department of Mechanical Science and Engineering and Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

Physical Review Letters (Impact Factor: 7.73). 06/2009; 102(19):194301. DOI: 10.1103/PhysRevLett.102.194301 Source: PubMed

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**ABSTRACT:**Two dimensional multi-atom Archimedean-like phononic crystals (MAPCs) can be obtained by adding "atoms" at suitable positions in primitive cells of traditional simple lattices. Band structures of solid-solid and solid-air MAPCs are computed by the finite element method in conjunction with the Bloch theory. For the solid-solid system, our results show that the MAPCs can be suitably designed to split and shift band gaps of the corresponding traditional simple phononic crystal (i.e., with only one scatterer inside a primitive cell). For the solid-air system, the MAPCs have more and wider band gaps than the corresponding traditional simple phononic crystal. Numerical calculations for both solid-solid and solid-air MAPCs show that the band gap of traditional simple phononic crystal can be tuned by appropriately adding "atoms" into its primitive cell.International Journal of Computational Materials ScieInternational Journal of Computational Materials Science and Engineeringnce and Engineering 10/2012; 01(02). - [Show abstract] [Hide abstract]

**ABSTRACT:**The wave propagation characteristics of an acoustic metamaterial composed of periodically repeated one-dimensional Helmholtz resonator array was investigated considering the effects of dimensional changes of the resonator geometry on the transmission coefficient and band gap. The effective impedance and transmission coefficient of the acoustic metamaterials are obtained based on the acoustic transmission line method. The designed acoustic metamaterials exhibit band gaps and negative bulk modulus that are non-existent properties in the nature. The band gap of the acoustic metamaterial is strongly dependent on the geometry parameters of Helmholtz resonators and lattice spacing. Also, a new type of metamaterial that is periodically constructed with two different resonators was designed to open the local resonance band gap without change of Bragg scattering.Transactions of the Korean Society for Noise and Vibration Engineering. 01/2013; 23(2). -
##### Article: Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial

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**ABSTRACT:**Supplementary information available for this article at http://www.nature.com/ncomms/2014/141124/ncomms6510/suppinfo/ncomms6510_S1.htmlNat Commun. 11/2014; 5.

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