期刊
JOURNAL OF PHYSICS D-APPLIED PHYSICS
卷 54, 期 28, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/1361-6463/abf9d9
关键词
non-Hermitian systems; topological modes; non-reciprocal wave propagation; metamaterials; metastructures
资金
- SAo Paulo Research Foundation (FAPESP) [2018/15894-0, 2019/20235-9, 2020/07703-0]
- National Science Foundation (NSF) through the EFRI [1741685]
- Army Research Office (ARO) [W911NF-18-1-0036]
- Emerging Frontiers & Multidisciplinary Activities
- Directorate For Engineering [1741685] Funding Source: National Science Foundation
This work investigates non-Hermitian elastic waveguides with periodically applied proportional feedback efforts, showing non-reciprocal frequency components in dispersion diagrams and the effects of feedback sign and locality on wave propagation. The results contribute to designing metamaterials with novel properties and potential technological applications.
In this work, we investigate non-Hermitian (NH) elastic waveguides with periodically applied proportional feedback efforts, implemented through piezoelectric sensors and actuators. Using one-dimensional spectral models for longitudinal motion, it is shown that dispersion diagrams of this family of structures exhibit non-reciprocal imaginary frequency components, manifesting as wave attenuation or amplification along opposite directions for all Bloch bands (BBs). The effects of positive and negative proportional feedback, as well as local and non-local actuation are investigated. Overall, switching the sign of the feedback effort inverts the amplification direction, while increasing the degree of non-locality produces splitting of the BBs into multiple bands with interchanging non-reciprocal behavior. Furthermore, skin modes localized at the boundaries of finite domains are investigated and successfully predicted by the winding number of the complex dispersion bands. These results contribute to recent efforts in designing metamaterials with novel properties associated with the physics of non-Hermitian systems, which may find fruitful technological applications relying on vibration and noise control, wave localization, filtering and multiplexing.
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