Experimental demonstration of topological waveguiding in elastic plates with local resonators

TL;DR

This paper demonstrates both numerically and experimentally that elastic plates with bolted resonators can support topologically protected waveguiding, enabling robust flexural wave transport around sharp bends at low frequencies.

Contribution

It introduces a novel elastic plate design with bolted resonators to realize topological waveguiding and pseudo-spin Hall effects in a continuum system.

Findings

Existence of double Dirac cones near bolt resonance frequency

Opening of multiple topological bandgaps including a complete bandgap

Guided flexural waves around sharp bends within the bandgap

Abstract

It is recent that the emergence of topological insulators in condensed matter physics has inspired analogous wave phenomena in mechanical systems, mostly in the setting of discrete lattice models. Here we report a numerical and experimental demonstration of topological waveguiding in a continuum plate. We take a ubiquitous design of a bolted elastic plate and show that such a design allows us to invoke the pseudo-spin Hall effect at remarkably low frequencies. We harness the complex interaction of the bolts and the plate to show the existence of a pair of double Dirac cones near the resonant frequency of the bolt. The manipulation of bolted patterns results in the opening of multiple topological bandgaps, including a complete bandgap that forbids all plate modes. We demonstrate that inside this bandgap, the interface between two topologically distinct zones can guide flexural waves crisply around sharp bends.