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Characterizing Dissipative Elastic Metamaterials Produced by Additive Manufacturing
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Static elastic cloaking, low-frequency elastic wave transparency and neutral inclusions.
Andrew N Norris1, William J Parnell2
1Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, NJ 08854-8058, USA.
Proceedings. Mathematical, Physical, and Engineering Sciences
|September 14, 2020
Summary
Researchers established new links between static elastic cloaking, low-frequency elastic wave scattering, and neutral inclusions (NIs). Anisotropic shells enable static cloaking, while isotropic materials can reduce scattering, offering material design options.
Area of Science:
- Solid Mechanics
- Acoustics
- Materials Science
Background:
- Elastic cloaking aims to render objects invisible to elastic waves.
- Low-frequency elastic wave scattering is a key challenge in wave manipulation.
- Neutral inclusions (NIs) offer a theoretical framework for wave transparency.
Purpose of the Study:
- To establish connections between static elastic cloaking, low-frequency scattering, and neutral inclusions in 2D elasticity.
- To determine shell material properties for achieving both static cloaking and scattering reduction.
- To introduce and analyze the concept of 'strong' neutral inclusions.
Main Methods:
- Analysis of a core-shell cylindrical inclusion in an elastic matrix.
- Derivation of implicit solutions for shell material properties.
- Distinguishing between 'weak' and 'strong' neutral inclusions.
Main Results:
- Static cloaking requires anisotropic shell materials.
- Scattering reduction can be achieved with simpler isotropic materials.
- Strong NIs, using standard anisotropic shells, can act as perfect static cloaks.
Conclusions:
- The study provides a unified framework linking static cloaking, scattering reduction, and neutral inclusions.
- Material designers can leverage these findings for quasi-static elastic cloaking applications.
- The introduction of strong NIs extends previous theoretical results for wave transparency.
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