Tailored elastic surface to body wave Umklapp conversion

Abstract

Elastic waves guided along surfaces dominate applications in geophysics, ultrasonic inspection, mechanical vibration, and surface acoustic wave devices; precise manipulation of surface Rayleigh waves and their coupling with polarized body waves presents a challenge that offers to unlock the flexibility in wave transport required for efficient energy harvesting and vibration mitigation devices. We design elastic metasurfaces, consisting of a graded array of rod resonators attached to an elastic substrate that, together with critical insight from Umklapp scattering in phonon-electron systems, allow us to leverage the transfer of crystal momentum; we mode-convert Rayleigh surface waves into bulk waves that form tunable beams. Experiments, theory and simulation verify that these tailored Umklapp mechanisms play a key role in coupling surface Rayleigh waves to reversed bulk shear and compressional waves independently, thereby creating passive self-phased arrays allowing for tunable redirection and wave focusing within the bulk medium.

5 pages of text with 3 figures plus 3 pages of supplemental text with 5 supplemental figures

References in corpus (7)

• Seismic metasurfaces: Sub-wavelength resonators and Rayleigh wave interaction
• Manipulating waves by distilling frequencies: a tunable shunt-enabled rainbow trap
• Enhancement of sound in chirped sonic crystals
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• Graded resonator arrays for spatial frequency separation and amplification of water waves
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Cited by in corpus (10)

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• Selective mode conversion and rainbow trapping via graded elastic waveguides
• Lamb's problem for a half-space coupled to a generic distribution of oscillators at the surface
• Tailored Topological Edge Waves via Chiral Hierarchical Metamaterials
• A multiple scattering formulation for finite-size flexural metasurfaces
• Homogeneous Dislocation-Induced Rainbow Concentrating for Elastic Waves
• Rayleigh wave propagation in nonlinear metasurfaces
• Surface corrugated laminates as elastic grating couplers: splitting of SV- and P-waves by selective diffraction
• The Elastic Spiral Phase Pipe