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Resonant metalenses for flexural waves in plates
1Department of Mathematics, Imperial College, South Kensington, London, SW7 2AZ, United Kingdom andree.colombi@gmail.com.
The Journal of the Acoustical Society of America
|December 3, 2016
Summary
Researchers designed gradient index metalenses for flexural waves using rod clusters. By tuning rod height, they controlled wave velocity for Luneburg, Maxwell, and 90° rotating lens applications.
Area of Science:
- Acoustics
- Materials Science
- Metamaterials
Background:
- Local resonance in rod clusters on thin plates creates subwavelength bandgaps and slow group velocities.
- Rod height is a key parameter influencing the slow velocity branch in these acoustic metamaterials.
Purpose of the Study:
- To design and test gradient index metalenses for flexural waves.
- To utilize tunable spatial velocity gradients in rod-cluster metamaterials for lens applications.
- To create Luneburg, Maxwell, and 90° rotating metalenses by controlling refractive index profiles.
Main Methods:
- Combined theoretical analysis with three-dimensional numerical simulations.
- Investigated flexural wave propagation in a narrow band around 4 kHz.
- Tuned the height of closely spaced rods to achieve desired refractive index gradients.
Main Results:
- Demonstrated the feasibility of designing gradient index metalenses by adjusting rod height.
- Analyzed the performance of Luneburg, Maxwell, and 90° rotating metalenses.
- Validated theoretical predictions through numerical simulations.
Conclusions:
- Rod-cluster metamaterials offer a tunable platform for creating gradient index lenses for flexural waves.
- Adjusting rod height effectively controls the refractive index profile for acoustic lensing.
- The designed metalenses show promising performance for manipulating flexural wave propagation.
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