Lu Yongling, Wang Zhen, Zhu Xueqiong, Hu Chengbo, Yang Jinggang, Wu Yipeng
Research Institute of State Grid Jiangsu Electric Power Co., Ltd., Nanjing 211103, China.
State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Micromachines (Basel). 2022 May 30;13(6):862. doi: 10.3390/mi13060862.
Topological metamaterial has been a research hotpot in both physics and engineering due to its unique ability of wave manipulation. The topological interface state, which can efficiently and robustly centralize the elastic wave energy, is promising to attain high-performance energy harvesting. Since most of environmental vibration energy is in low frequency range, the interface state is required to be designed at subwavelength range. To this end, this paper developed a topological metamaterial beam with local resonators and studied its energy-harvesting performance. First, the unit cell of this topological metamaterial beam consists of a host beam with two pairs of parasitic beams with tip mass. Then, the band structure and topological features are determined. It is revealed that by tuning the distance between these two pairs of parasitic beams, band inversion where topological features inverse can be obtained. Then, two sub-chains, their design based on two topologically distinct unit cells, are assembled together with a piezoelectric transducer placed at the conjunction, yielding the locally resonant, topological, metamaterial, beam-based piezoelectric energy harvester. After that, its transmittance property and output power were obtained by using the frequency domain analysis of COMSOL Multiphysics. It is clear that the subwavelength interface state is obtained at the band-folding bandgap. Meanwhile, in the interface state, elastic wave energy is successfully centralized at the conjunction. From the response distribution, it is found that the maximum response takes place on the parasitic beam rather than the host beam. Therefore, the piezoelectric transducer is recommended to be placed on the parasitic beam rather than host beam. Finally, the robustness of the topological interface state and its potential advantages on energy harvesting were studied by introducing a local defect. It is clear that in the interface state, the maximum response is always located at the conjunction regardless of the defect degree and location. In other words, the piezoelectric transducer placed at the conjunction can maintain a stable and high-efficiency output power in the interface state, which makes the whole system very reliable in practical implementation.
由于其独特的波操控能力，拓扑超材料一直是物理学和工程学领域的研究热点。拓扑界面态能够高效且稳健地集中弹性波能量，有望实现高性能的能量收集。由于大部分环境振动能量处于低频范围，因此需要在亚波长范围内设计界面态。为此，本文开发了一种带有局部谐振器的拓扑超材料梁，并研究了其能量收集性能。首先，这种拓扑超材料梁的单元胞由一根主梁和两对带有端部质量块的寄生梁组成。然后，确定了能带结构和拓扑特征。结果表明，通过调整这两对寄生梁之间的距离，可以获得拓扑特征反转的能带反转。接着，基于两个拓扑不同的单元胞设计了两个子链，并将它们与置于连接处的压电换能器组装在一起，得到了基于局部谐振、拓扑超材料梁的压电能量收集器。之后，通过使用COMSOL Multiphysics的频域分析获得了其透射特性和输出功率。显然，在能带折叠带隙处获得了亚波长界面态。同时，在界面态下，弹性波能量成功地集中在连接处。从响应分布可以发现，最大响应发生在寄生梁而非主梁上。因此，建议将压电换能器放置在寄生梁而非主梁上。最后，通过引入局部缺陷研究了拓扑界面态的鲁棒性及其在能量收集方面的潜在优势。显然，在界面态下，无论缺陷程度和位置如何，最大响应始终位于连接处。换句话说，置于连接处的压电换能器在界面态下能够保持稳定且高效的输出功率，这使得整个系统在实际应用中非常可靠。
