Cloaking In-Plane Elastic Waves with Swiss Rolls.
Younes Achaoui1, André Diatta2, Muamer Kadic1
1Institut FEMTO-ST, UMR 6174, CNRS, Université de Bourgogne Franche-Comté, 25000 Besanco̧n, France.
Materials (Basel, Switzerland)
|January 23, 2020
Summary
This study presents a novel cylindrical cloak design using Swiss roll inclusions to hide objects from shear waves. The cloak achieves cloaking at resonant frequencies by manipulating wave propagation through a structured medium.
Area of Science:
- Acoustics and wave physics
- Materials science and engineering
- Metamaterials design
Background:
- Metamaterials enable manipulation of wave phenomena beyond natural material limits.
- Elastodynamic cloaking aims to render objects invisible to mechanical waves.
- Existing cloaking designs face challenges with specific wave types and frequency ranges.
Purpose of the Study:
- To design and analyze a cylindrical cloak for coupled in-plane shear waves.
- To investigate the effectiveness of Swiss roll inclusions in cloaking applications.
- To explore the role of Willis and Cosserat media in elastodynamic cloaking.
Main Methods:
- Utilizing concentric layers of sub-wavelength resonant stress-free Swiss roll inclusions.
- Applying Pendry's transform with a modified geometric transform starting from a Willis medium.
- Analyzing the behavior of displacement fields and Willis equation tensors.
- Simulating cloaking performance for a shear polarized source near a clamped obstacle.
Main Results:
- Achieved partial cloaking for shear waves at specific resonant frequencies.
- Demonstrated strong Willis coupling in the structured medium.
- Observed mitigation of Willis and Cosserat media roles in cloaking.
- Identified potential chiral elastic effects.
Conclusions:
- The proposed Swiss roll inclusion cloak offers a viable approach for shear wave cloaking.
- The modified geometric transform and Willis medium consideration are crucial for design.
- The structured medium effectively approximates the effective medium for cloaking applications.
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