Nonlocal elastic metasurfaces: Enabling broadband wave control via intentional nonlocality

Area of Science:

• Solid Mechanics
• Materials Science
• Acoustics

Background:

• Elastic metasurfaces enable subwavelength control of stress waves but suffer from narrow bandwidth.
• Nonlocality, a known method to broaden operating ranges in electromagnetic metamaterials, is challenging to implement in mechanical systems.

Purpose of the Study:

• To introduce intentional nonlocality as a mechanism for designing passive elastic metasurfaces with broadband performance.
• To demonstrate a novel method for achieving broadband wave control in elastic systems.

Main Methods:

• Exploiting nonlocal forces between resonant unit cells via carefully designed flexible elements.
• Utilizing semianalytical and numerical models to identify design parameters and assess performance.
• Experimental validation of the nonlocal metasurface concept in a thin-plate waveguide.

Main Results:

• Successfully designed passive elastic metasurfaces with exceptionally broadband operating ranges.
• Demonstrated that nonlocal coupling forces enable wavenumber-dependent phase-gradient profiles.
• Experimental and numerical results confirm the feasibility and broadband wave control capabilities of the intentionally nonlocal design.

Conclusions:

• Intentional nonlocality is a viable fundamental mechanism for overcoming bandwidth limitations in elastic metasurfaces.
• The developed nonlocal metasurface design offers a passive and effective solution for broadband wave control.
• This work paves the way for practical applications of elastic metasurfaces requiring wide operational bandwidths.