Chiral Topological Phases in Designed Mechanical Networks

Mass-spring networks (MSNs) have long been used as approximate descriptions of biological and engineered systems, from actomyosin networks to mechanical trusses. In the last decade, MSNs have re-attracted theoretical interest as models for phononic metamaterials with exotic properties such as negati...

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Bibliographic Details
Main Authors: Ronellenfitsch, Henrik Michael, Dunkel, Joern
Other Authors: Massachusetts Institute of Technology. Department of Mathematics
Format: Article
Published: Frontiers Media SA 2020
Online Access:https://hdl.handle.net/1721.1/123870
Description
Summary:Mass-spring networks (MSNs) have long been used as approximate descriptions of biological and engineered systems, from actomyosin networks to mechanical trusses. In the last decade, MSNs have re-attracted theoretical interest as models for phononic metamaterials with exotic properties such as negative Poisson's ratio, negative effective mass, or gapped vibrational spectra. A numerical advantage of MSNs is their tuneability, which allows the inverse design of materials with pre-specified bandgaps. Building on this fact, we demonstrate here that designed MSNs, when subjected to Coriolis forces, can host topologically protected chiral edge modes at predetermined frequencies, thus enabling robust unidirectional transmission of mechanical waves. Similar to other recently discovered topological materials, the topological phases of MSNs can be classified by a Chern invariant related to time-reversal symmetry breaking. Keyword: Mechanical networks; Topological matter; Chern insulator; Classical mechanics and quantum mechanics; Edge modes