Coding Non-Hermitian Metamaterial Beams Based on Nonlocal Feedback Control
Yuqiang Gao, Lifeng Wang, Tianjian Lu
Abstract: Non-Hermitian system gives rise to unprecedented phenomena such as exceptional points, spectral topology, and non-Hermitian skin effects. Achieving non-Hermitian skin effects and fast switching of the propagation state of elastic waves in experiments remains a significant challenge. In this paper, a coding reconfigurable non-Hermitian metamaterial beam consisting of a host beam, piezoelectric patches, nonlocal feedback control circuits and encoders is proposed. The 0 and 1 codes are used to reconfiguration the metamaterial beams for control the wave propagation. In symmetric codes 0 0 and 1 1, nonlocal feedback control system can be used for tuning bandgap. In asymmetric codes 0 1 and 1 0, the actuator behaves as opposite control bending moments in opposite propagation directions, the spatial symmetry of the controlling force is broken. Nonlocal feedback control system is used to control the unidirectional propagation and skin effect of metamaterials. We experimentally observe the propagation ability of unidirectional amplified, attenuated and the skin effect in different energy bands. The multifunctional application of elastic waves, including a tunable bandgap, broadband nonreciprocal propagation, unidirectional amplification or attenuation and the skin effect are verified via experiments. The multifunctional application of the metamaterial beam can be easily and quickly reconfiguration by the programming encoder. Coding non-Hermitian metamaterials with nonlocal feedback control system provide new options for the intelligent development of vibration suppression and sensors.
文章链接：https://www.sciencedirect.com/science/article/pii/S0020740324009457
