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Elastic Waves Scattering without Conversion in Metamaterials with Simultaneous Zero Indices for Longitudinal and
Fengming Liu1,2, Zhengyou Liu3
1School of Science, Hubei University of Technology, Wuhan 430068, China.
Physical Review Letters
|November 10, 2015
Summary
This study explores elastic waves in zero-index metamaterials. Researchers found that while waves transmit, they block at resonances without mode conversion, unlike conventional materials.
Area of Science:
- Acoustics
- Materials Science
- Condensed Matter Physics
Background:
- Zero-index metamaterials (ZIMs) exhibit unique wave propagation properties.
- Conventional elastic media display mode conversion between longitudinal and transverse waves.
Purpose of the Study:
- To theoretically investigate elastic wave propagation in metamaterials with simultaneous zero indices for longitudinal and transverse waves.
- To explore wave behavior in ZIMs with embedded scattering objects.
- To present a design for a two-dimensional phononic crystal with peculiar elastic wave properties.
Main Methods:
- Theoretical investigation of elastic wave propagation.
- Analysis of wave transmission and scattering in metamaterial slabs with embedded cylinders.
- Examination of mode conversion phenomena at resonance.
Main Results:
- Elastic waves exhibit near-perfect transmission through ZIM slabs, demonstrating a cloaking effect.
- Strong elastic wave scattering occurs at resonance due to embedded objects.
- Counterintuitively, no mode conversion between longitudinal and transverse waves is observed during scattering.
Conclusions:
- Metamaterials with simultaneous zero indices offer novel control over elastic wave propagation.
- The absence of mode conversion in these ZIMs presents a significant departure from conventional elastic media.
- A two-dimensional phononic crystal design is proposed to realize these unique wave manipulation capabilities.
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