Topological spin-Hall edge states of flexural wave in perforated metamaterial plates

TL;DR

This study demonstrates topologically protected edge states for flexural waves in perforated phononic plates, revealing unidirectional, defect-robust wave propagation analogous to quantum spin Hall effects in elastic metamaterials.

Contribution

It introduces a topological elastic phononic system with a honeycomb perforated structure, analyzing edge states and their robustness using finite element simulations and effective Hamiltonian modeling.

Findings

Observation of topologically protected edge states

Unidirectional wave propagation along interfaces

Robustness against defects and sharp bends

Abstract

This paper investigates the pseudo-spin based edge states for flexural waves in a honeycomb perforated phononic plate, which behaves an elastic analogue of the quantum spin Hall effect. We utilize finite element method to analyse the dispersion for flexural waves based on Mindlin's plate theory. Topological transition takes place around a double Dirac cone at $\Gamma$ point by adjusting the sizes of perforated holes. We develop an effective Hamiltonian to describe the bands around the two doubly degenerated states and analyse the topological invariants. This further leads us to observe the topologically protected edge states localized at the interface between two lattices. We demonstrate the unidirectional propagation of the edge waves along topological interface, as well as their robustness against defects and sharp bends.