Acoustic/Phononic Topological Insulators Using Complementary Conductors
Abstract
Based on recently demonstrated line waves, and newly developed acoustic topological insulators, we will investigate materials that have complementary polarization properties for sound waves or phonons, and combine them into structures that can support one-way propagation. We will extend this concept to three dimensional structures that can be fabricated as simple layered materials or composites. After studying acoustic frequencies, we will explore phononic topological insulators for one-way thermal transport, and develop structures that can be fabricated from natural or nano-manufactured materials. Although heat can flow in both directions as dictated by the laws of thermodynamics, phonons in such a structure may propagate without scattering, leading to enhanced thermal conductivity. We will explore performance limits, and analyze possible future applications. Scientific Objectives The goal will be to discover or design new composite materials that support one-way propagation of mechanical vibrations, sound (acoustic waves), or heat (phonon waves). The most important output will be an understanding of what combinations of materials are required for acoustic/phononic topological insulators, specific designs, simulations, and measurements of their performance. Methods to be Employed We will begin by analyzing the band structure of mechanical systems based on simple mass/spring models, and proceed to simulations using commercially available software. We will fabricate prototypes using complementary acoustic structures. Initial structures will be 2D composites that can be built commercially, such as lithographically patterned free-standing metal structures, followed by 3D layered materials. Measurements will be performed using actuators and microphones, and nonlinearities will be studied by spectral analysis. We will extrapolate the work to the phononic regime based on either composites created from natural materials, or artificial structures built using nanolithography, and measure them with pulsed heat sources. Significance of the Proposed Effort This work will advance scientific understanding of acoustic and phonon propagation in the emerging area of phononic topological insulators, based on designs that are analogous to electromagnetic line waves. It may enable future applications in sound damping, shock absorption, and improved heat sink materials. Enhanced nonlinearity may also be useful for improved sound absorption.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1710453
Entities
People
- Daniel F. Sievenpiper
Organizations
- Army Contracting Command
- United States Army
- University of California, San Diego