Abstract Worldwide increases in noise levels due to growth in urban population, traffic and machinery have serious implications for health, productivity and quality of life. Prevention of sound transmission through walls and ceilings, particularly towards the lower frequency range of human hearing is important both because of its recent increase in levels and the challenges faced when providing sound insulation of long wavelength noise with existing construction methods. Mechanical metamaterials have the potential to address these challenges by enabling the creation of an artificial medium that generates far more attenuation of wave transmission than any existing material system. In part one of this work we design, model and test several local resonance structure (LRS) systems to provide the basis for future acoustic insulation systems. Three different LRS families were studied: spherically symmetric, flexural single-resonance and flexural multi-resonance. Some resonator elements showed a peak effective mass up to fifty times greater than their rest mass and achieved peak transmission losses 10s of dB greater than a non-resonant structure of equivalent surface density within the designated frequency range. By arranging sets of resonators with closely spaced resonance frequencies the transmission loss gains were spread over a wider frequency range and a reduction in the transmittance peak at the upper end of the band gap was achieved though variations in damping and mass of the resonators. A large ( 2.5 m 2 ) test article was constructed and tested under full scale diffuse field conditions such as are found in buildings. The results confirmed that the band gap observed in impedance tube measurements of small-scale LRS specimens survives. Modelling and testing results for more multilayer and multi-resonance systems are presented in part 2.

中文翻译：

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机械超材料衰减的倍增共振：第 1 部分 – 概念、初始验证和单层结构

摘要 由于城市人口、交通和机械的增长，全球噪声水平的增加对健康、生产力和生活质量产生了严重影响。防止声音通过墙壁和天花板传播，特别是在人类听觉的较低频率范围内传播很重要，因为它最近的水平增加以及在使用现有建筑方法提供长波噪声隔音时面临的挑战。机械超材料有可能通过创造一种人造介质来应对这些挑战，这种介质产生的波传输衰减比任何现有的材料系统都要大得多。在这项工作的第一部分，我们设计、建模和测试多个局部共振结构 (LRS) 系统，为未来的隔音系统提供基础。研究了三种不同的 LRS 系列：球对称、弯曲单共振和弯曲多共振。一些谐振器元件的峰值有效质量高达其静止质量的 50 倍，并且实现的峰值传输损耗比指定频率范围内等效表面密度的非谐振结构高 10 分贝。通过布置具有紧密间隔的谐振频率的谐振器组，传输损耗增益分布在更宽的频率范围内，并且通过谐振器的阻尼和质量的变化实现了带隙上端的透射率峰值的降低。一个大型 (2.5 m 2 ) 测试物品是在全尺寸扩散场条件下构建和测试的，例如在建筑物中发现的。结果证实，在小规模 LRS 样品的阻抗管测量中观察到的带隙仍然存在。第 2 部分介绍了更多多层和多谐振系统的建模和测试结果。