Manipulating elastic waves using topological modes: phase II

Abstract

Elastic metamaterials and phononic crystals have been investigated due to their extraordinary properties that allow vibration and acoustic attenuation as well as wave manipulation. The presence of the band gaps, frequency ranges in which wave and vibration disturbances will not propagate through the structure, is the key feature of these periodic media. Band gaps have paved the way to create acoustic and vibration barriers, seismic shielding, acoustic diodes, two-dimensional waveguides, sensors, energy harvesting devices among other wave manipulation phenomena. Recently considered in the acoustic and elasto-dynamics fields, breaking symmetries and topological insulators present a wide range of open topics that have high potential to address engineering problems, to create new technologies and to affect the every-day-life. In topological insulators, the bulk is isolated while topologically protected states, such as edge and interface modes, are hosted in one dimension lower than the bulk. In addition, quasi-periodic and fractal systems have also been explored to enabling, among other phenomena, a robustly transfer of energy between edge and interface wave modes keeping the bulk isolated. They may also host topologically protected states in at least two dimensions lower than the bulk, and hence, considered as higher-order topological insulators. Recently, non-Hermitian systems have also been considered to create topological insulators with one-way propagation. Therefore, in this research project, the motivation is to use concepts from condensed matter physics, such as breaking space and time symmetries, to manipulate elastic waves in a more efficient and versatile way by means of quasi-periodic and fractal structures as well as non-Hermitian systems. Theoretical analysis, numerical simulations and experimental observations will be employed to explore this rich and dynamic research area with interface between physics and engineering. (AU)