Spiral-Based Phononic Plates: From Wave Beaming to Topological Insulators

Area of Science:

• Materials Science
• Acoustics
• Solid State Physics

Background:

• Phononic crystals and metamaterials control elastic waves using Bragg scattering, local resonances, and inertial amplification.
• Existing designs often rely on ad hoc, problem-specific geometries.
• A unified platform for these mechanisms is lacking.

Purpose of the Study:

• To present a novel platform for phononic materials utilizing a lattice of spiraling unit cells.
• To demonstrate simultaneous Bragg scattering, local resonances, and inertial amplification.
• To showcase applications in wave beaming and topological insulation.

Main Methods:

• Design and simulation of phononic materials with spiraling unit cells.
• Analysis of elastic wave propagation and dispersion control.
• Experimental validation of wave beaming and topological properties.

Main Results:

• A phononic material platform integrating Bragg scattering, local resonances, and inertial amplification was developed.
• A wave beaming plate demonstrated arbitrary angle beaming, tunable by frequency or spiral orientation.
• A topological insulator plate exhibited resonance-based Dirac cones below the Bragg limit.

Conclusions:

• The spiraling unit cell platform offers a versatile approach to phononic material design.
• This platform enables precise control over elastic waves, including sub-wavelength phenomena.
• The demonstrated applications highlight potential for advanced acoustic and elastic wave devices.