Polar metamaterials: A new outlook on resonance for cloaking applications

Abstract

Rotationally resonant metamaterials are leveraged to answer a longstanding question regarding the existence of transformation-invariant elastic materials and the ad-hoc possibility of transformationbased passive cloaking in full plane elastodynamics. Combined with tailored lattice geometries, rotational resonance is found to induce a polar and chiral behavior; that is a behavior lacking stress and mirror symmetries, respectively. The central, and simple, idea is that a population of rotating resonators can exert a density of body torques strong enough to modify the balance of angular momentum on which hang these symmetries. The obtained polar metamaterials are used as building blocks of a cloaking device. Numerical tests show satisfactory cloaking performance under pressure and shear probing waves, further coupled through a free boundary. The work sheds new light on the phenomenon of resonance in metamaterials and should help put transformation elastodynamics on equal footing with transformation acoustics and optics.

References in corpus (5)

• Acoustic cloaking theory
• Employing pre-stress to generate finite cloaks for antiplane elastic waves
• Hyperelastic cloaking theory: Transformation elasticity with pre-stressed solids
• Nonlinear pre-stress for cloaking from antiplane elastic waves
• Transformation cloaking and radial approximations for flexural waves in elastic plates

Cited by in corpus (3)

• Spin-orbit interactions of transverse sound
• Microtwist elasticity: A continuum approach to zero modes and topological polarization in Kagome lattices
• Willis elasticity from microcontinuum field theories: Asymptotics, microstructure-property relationships, and cloaking