The current study on acoustic energy harvesting is based on a single-band vibroacoustic conversion performed by either structural resonance or local resonance. In this paper, we propose a Helmholtz acoustic metamaterial (HAM) piezoelectric device having dual-band acoustic energy harvesting characteristics. The Helmholtz resonator of the metamaterial amplifies both structural and local resonances. HAM is designed based on the Bloch theorem, plane wave expansion method, and electroacoustic impedance analogy. Numerical simulation is performed to show the sound pressure amplification effect of HAM. A piezoelectric disk is bonded on the point defect of the Helmholtz metamaterial for energy localization and conversion, and HAM is clamped on a self-made experimental platform by simply supported boundary conditions on four sides. The time–frequency image of the voltage output from the swept frequency experiment shows two distinct bands corresponding to the structural resonance frequency of 381 Hz with the band width of 45 Hz and the local resonance frequency of 1526 Hz with the band width of 290 Hz. The peak-to-peak power of HAM is 0.13 mW, and its peak-to-peak voltage is 3.2 V at 391 Hz with the sound pressure of 31 Pa. At the input sound pressure of 23.32 Pa and frequency of 1526 Hz, the output voltage and power are found to be 1.5 V and 0.11 mW, respectively. Under the same amplitude of the input sound pressure, the output power of HAM is found 12.7 times and 4.4 times higher than those of the traditional acoustic metamaterial in the structural and local resonance bands, respectively. Field tests validate the superiority of the designed structure. In the milling environment, the voltage–pressure transmission rate reaches 0.11 V/Pa. The acoustic energy wall composed of HAM will be capable to provide a power solution for an intelligent factory.

当前对声能收集的研究基于由结构共振或局部共振执行的单波段振动声转换。在本文中，我们提出了一种具有双波段声能收集特性的亥姆霍兹声学超材料 (HAM) 压电器件。超材料的亥姆霍兹共振器放大了结构共振和局部共振。HAM 是基于布洛赫定理、平面波展开方法和电声阻抗类比设计的。数值模拟显示了HAM的声压放大效果。将压电盘粘合在亥姆霍兹超材料的点缺陷上进行能量定域和转换，并通过四边简支边界条件将HAM夹在自制的实验平台上。来自扫频实验的电压输出的时频图像显示了两个不同的频带，对应于 381 Hz 的结构共振频率，带宽为 45 Hz，局部共振频率为 1526 Hz，带宽为 290 Hz。HAM 的峰峰值功率为 0.13 mW，其峰峰值电压为 3.2 V，391 Hz，声压为 31 Pa。在输入声压为 23.32 Pa，频率为 1526 Hz 时，发现输出电压和功率分别为 1.5 V 和 0.11 mW。在输入声压幅度相同的情况下，HAM 的输出功率在结构和局部共振带上分别比传统声学超材料高 12.7 倍和 4.4 倍。现场测试验证了设计结构的优越性。在铣削环境中，电压-压力传递率达到0.11 V/Pa。由HAM构成的声能墙将为智能工厂提供动力解决方案。