We investigate theoretically and experimentally a nonlocal micropolar metabeam shunted with piezoelectric elements modulated by electronic feed-forward control. Since the nonlocal feed-forward control breaks inversion symmetry, the proposed metabeam supports nonreciprocal flexural wave propagation, featuring unidirectional amplification/attenuation and non-Hermitian skin effect. The unidirectional wave propagation is attributed to the energy conversion between electronic and mechanical parts. Also, the nonlocal metabeam is capable of realizing mechanical roton-like dispersion whose reciprocity can be broken by the programmable feed-forward control. The nonlocal micropolar metabeam could pave the ways for designing non-Hermitian topological mechanical insulators and metamaterials.

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Qian Wu and Guoliang Huang, "Engineering wave nonreciprocity in a nonlocal metabeam," Proc. SPIE PC12483, Active and Passive Smart Structures and Integrated Systems XVII, PC1248308 (Presented at SPIE Smart Structures + Nondestructive Evaluation: March 13, 2023; Published: 28 April 2023); https://doi.org/10.1117/12.2657638.6323742016112.