The all-direction vibration and noise control by metastructures have received high demands in the vibroacoustic community in the recent past to solve multiple vibration and noise-related engineering problems. This class of elastic metamaterial has grasped a strong root in this community due to its versatile wave manipulation characteristics, including frequency bandgap property. Inspired by the idea of metamaterial and computational mechanics in breakthrough research for vibration and noise control technology, the present study proposes a novel 3D phononic metastructure that is capable of generating low-frequency extremely wide three-dimensional complete bandgap with relative bandwidth \({{\Delta \omega } \mathord{\left/ {\vphantom {{\Delta \omega } {\omega_{{\text{c}}} }}} \right. \kern-\nulldelimiterspace} {\omega_{{\text{c}}} }} = 171.5\%\). The study is based on analytical modeling, numerical finite element analysis and experiment on 3D printed prototype. The proposed monolithic metastructure is comprised of elastic beams connected orthogonally with rigid spherical masses. The axial compression mode of a complete unit cell structure and the flexural stiffness of beams are manipulated to generate low-frequency extremely wide bandgap. By the principle of modal masses participation/mode separation, the opening and closing of the bandgap is analyzed. The results are corroborated by two different numerical FE solutions on the frequency response spectrum, and the models are validated by performing a vibration test on 3D printed prototype. The wave attenuation over ultrawide frequency range is demonstrated through numerical and experimental approaches, and excellent agreement is reported. The proposed monolithic metastructure design may find potential applications in industrial and infrastructural devices where noise and vibration control over ultrawide frequency range are desirable in all directions.

Graphic abstract

中文翻译：

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通过3D整体机械超薄结构实现的超宽带隙，可控制振动和噪声

近来，通过结构的全向振动和噪声控制已经在振动声社区中受到了很高的要求，以解决与振动和噪声有关的多种工程问题。此类弹性超材料由于其通用的波控制特性（包括带隙特性）而在该社区中扎下了坚实的基础。在振动和噪声控制技术的突破性研究中，受到超材料和计算力学思想的启发，本研究提出了一种新型的3D声子元结构，该结构能够生成具有相对带宽的低频超宽三维完整带隙\（{{\ Delta \ omega} \ mathord {\ left / {\ vphantom {{\ Delta \ omega} {\ omega _ {{\ text {c}}}}}}} \ right。\ kern- \ nulldelimiterspace} { \ omega _ {{\ text {c}}}}} = 171.5 \％\）。该研究基于分析建模，数值有限元分析和3D打印原型的实验。所提出的整体式元结构由与刚性球形块正交连接的弹性梁组成。操纵完整的晶胞结构的轴向压缩模式和梁的抗弯刚度，以产生低频极宽的带隙。根据模态质量参与/模态分离的原理，分析了带隙的打开和闭合。通过在频率响应频谱上使用两种不同的数值有限元解决方案来验证结果，并通过对3D打印原型进行振动测试来验证模型。通过数值和实验方法证明了在超宽频率范围内的波衰减，并报道了极好的一致性。

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