Article

Hybrid elastic solids.

Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Nature Material (Impact Factor: 36.43). 06/2011; 10(8):620-4. DOI: 10.1038/nmat3043
Source: PubMed

ABSTRACT Metamaterials can exhibit electromagnetic and elastic characteristics beyond those found in nature. In this work, we present a design of elastic metamaterial that exhibits multiple resonances in its building blocks. Band structure calculations show two negative dispersion bands, of which one supports only compressional waves and thereby blurs the distinction between a fluid and a solid over a finite frequency regime, whereas the other displays 'super anisotropy' in which compressional waves and shear waves can propagate only along different directions. Such unusual characteristics, well explained by the effective medium theory, have no comparable analogue in conventional solids and may lead to novel applications.

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Available from: Pai Peng, Jun 12, 2014
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    04/2015; 6(1):1-12. DOI:10.1080/19475411.2015.1029604
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    ABSTRACT: Elastic metamaterials have been extensively investigated due to their significant effects on controlling propagation of elastic waves. One of the most interesting properties is the generation of band gaps, in which subwavelength elastic waves cannot propagate through. In the study, a new class of active elastic metamaterials with negative capacitance piezoelectric shunting is presented. We first investigated dispersion curves and band gap control of an active mass-in-mass lattice system. The unit cell of the mass-in-mass lattice system consists of the inner masses connected by active linear springs to represent negative capacitance piezoelectric shunting. It was demonstrated that the band gaps can be actively controlled and tuned by varying effective stiffness constant of the linear spring through appropriately selecting the value of negative capacitance. The promising application was then demonstrated in the active elastic metamaterial plate integrated with the negative capacitance shunted piezoelectric patches for band gap control of both the longitudinal and bending waves. It can be found that the location and the extent of the induced band gap of the elastic metamaterial can be effectively tuned by using shunted piezoelectric patch with different values of negative capacitance, especially for extremely low-frequency cases.
    Journal of Vibration and Acoustics 12/2014; 136(6):061008. DOI:10.1115/1.4028378 · 0.71 Impact Factor
  • Applied Mechanics Reviews 07/2014; 66(4):040802. DOI:10.1115/1.4026911 · 2.00 Impact Factor
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    ABSTRACT: A metamaterial model that possesses simultaneously negative effective mass density and negative effective Young’s modulus is proposed in this study. Dispersion curves and dynamic responses of the model are investigated. In the double negative frequency region, it is demonstrated that the phase velocity is negative. In addition, it was found that the band gap region of the metamaterial can be predicted accurately by taking parts of single-unit cell to analyze the steady-state response. The design is also fabricated by a 3D printer.
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    04/2015; 6(1):1-12. DOI:10.1080/19475411.2015.1029604