Edge Modes and Asymmetric Wave Transport in Topological Lattices: Experimental Characterization at Finite Frequencies

Abstract

Although topological mechanical metamaterials have been extensively studied from a theoretical perspective, their experimental characterization has been lagging. To address this shortcoming, we present a systematic laser-assisted experimental characterization of topological kagome lattices, aimed at elucidating their in-plane phononic and topological characteristics. We specifically explore the continuum elasticity limit, which is established when the ideal hinges that appear in the theoretical models are replaced by ligaments capable of supporting bending deformation, as observed for instance in realistic physical lattices. We reveal how the zero-energy floppy edge modes predicted for ideal configurations morph into finite-frequency phonon modes that localize at the edges. By probing the lattices with carefully designed excitation signals, we are able to extract and characterize all the features of a complex low-frequency acoustic regime in which bulk modes and topological edge modes overlap and entangle in response. The experiments provide unequivocal evidence of the existence of strong asymmetric wave transport regimes at finite frequencies.

arXiv comment8 pages, 10 figures

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• Switchable phonon diodes using nonlinear topological Maxwell lattices
• Universal Continuum Theory for Topological Edge Soft Modes
• Prestress tuning of negative refraction and wave channeling from flexural sources
• Topological elasticity of flexible structures
• Soft mechanical metamaterials with transformable topology protected by stress caching
• Signatures of Topological Phonons in Superisostatic Lattices
• Breakdown of Conventional Winding Number Calculation in One-Dimensional Lattices with Interactions Beyond Nearest Neighbors
• Symmetry of the phonon landscape across the duality boundary of twisted kagomes lattices
• Topological Flexural Modes in Polarized Bilayer Lattices
• Strongly Nonlinear Topological Phases of Cascaded Topoelectrical Circuits
• Dynamics of self-dual kagome metamaterials and the emergence of fragile topology
• Omnimodal topological polarization of bilayer networks: analysis in the Maxwell limit and experiments on a 3D-printed prototype
• Finite-Frequency Topological Maxwell Modes in Mechanical Self-Dual Kagome Lattices
• Fully-Polarized Topological Isostatic Metamaterials in Three Dimensions
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• Cell augmentation framework for topological lattices
• 3D Topologically Polarized Elastic Metamaterials Enable Asymmetric Energy Isolation at Low Frequencies
• Hierarchical Topological States without Dimension Reduction
• A way to hypo-elastic artificial materials without a strain potential and displaying flutter instability