A negative Poisson's ratio arc curve Helmholtz resonator structure is proposed to address the difficulty of achieving perfect low-frequency absorption in traditional absorbing structures at ultra-subwavelength scales for subaqueous low-frequency sound waves. The shape of the embedded tube is designed as a circular tube and a regular hexagonal tube, with the two shapes symmetrically distributed about the center of the circle. Furthermore, the traditional concave sandwich structure with negative Poisson's ratio has been modified to ensure outstanding sound absorption performance while preserving the overall dimensions. The structure is simulated using the finite element software COMSOL and validated through experiments using a standing wave tube absorber test. The experimental and simulated results show a high level of consistency. The findings demonstrate that the arc-shaped Helmholtz resonator structure with a negative Poisson's ratio significantly lowers the resonant absorption peak frequency of the Helmholtz resonator. This modification allows the structure to exhibit exceptional sound absorption performance within the frequency range of 520–930 Hz, with an average sound absorption coefficient surpassing 0.9, achieving near-perfect absorption of sound waves. The absorber structure achieves an absorption peak of 0.99 at a frequency of 740 Hz, with a thickness that is ultra-subwavelength, being only 1/15 of the corresponding wavelength for the absorption peak frequency, demonstrating its deep subwavelength dimensional characteristics. Even when the structure's height is 30 mm, there is still a wide absorption band, with a bandwidth ratio of 68 % (sound absorption coefficient > 0.5). Furthermore, an energy absorption characteristic analysis is conducted on the negative Poisson's ratio arc curve Helmholtz resonator structure, showing that the energy absorption performance is almost the same between structures with and without microperforated plates. Therefore, creating micro-perforations on the panel does not affect the energy absorption characteristics of the structure.

中文翻译：

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负泊松比拱形曲线亥姆霍兹谐振器宽带低频吸声及吸能的改进

针对传统吸波结构在超亚波长尺度对水下低频声波实现完美低频吸收的困难，提出了一种负泊松比圆弧曲线亥姆霍兹谐振器结构。预埋管的形状设计为圆形管和正六角形管，两种形状关于圆心对称分布。此外，对传统的负泊松比凹形夹层结构进行了修改，以在保持整体尺寸的同时确保出色的吸声性能。该结构使用有限元软件 COMSOL 进行模拟，并通过驻波管吸波器测试进行实验验证。实验和模拟结果显示出高度的一致性。研究结果表明，负泊松比的弧形亥姆霍兹谐振器结构显着降低了亥姆霍兹谐振器的谐振吸收峰值频率。这一修改使得结构在520-930 Hz的频率范围内表现出优异的吸声性能，平均吸声系数超过0.9，实现了近乎完美的声波吸收。该吸波体结构在740 Hz频率下实现了0.99的吸收峰值，厚度为超亚波长，仅为吸收峰值频率对应波长的1/15，展现了其深亚波长尺寸特性。即使结构高度为30mm，仍然存在较宽的吸收带，带宽比达68%（吸声系数>0.5）。此外，对负泊松比圆弧曲线亥姆霍兹谐振器结构进行了能量吸收特性分析，表明有微孔板和无微孔板结构的能量吸收性能几乎相同。因此，在面板上创建微穿孔不会影响结构的能量吸收特性。