Elastic and acoustic metamaterials are man-made structures designed to control and manipulate waves through band gaps. The generalized bandwidth of metamaterials with locally resonant (LR) band gaps is usually narrow, limiting their applications in noise and vibration control. On the other hand, nonlinear metamaterials with dipolar resonances can present a broad chaotic band with low amplitude resonances due to bridging coupling, which is only observed under sufficiently large excitation amplitudes. In this work, we show that bridging-coupling phenomenon can also be observed in linear metamaterials with dipolar resonance, producing a special pass band with low amplitude resonances at low frequencies without excitation amplitude dependence. Such phenomenon emerges in a modified resonant metachain with zigzag interconnections and is based on the isomerism of traditional metamaterials. Although this modified isomer preserves the static stiffness and mass density (i.e., static performance) of the original metamaterial, its dispersive behavior presents interesting properties (i.e., branches with negative mass features and overlapping of opposite group velocity), resulting in an overall negative effective mass between the LR band gaps that is responsible for the remote interaction and the enhanced wave performance. In addition to the theoretical discussions, the bridging coupling is experimentally observed in a three-dimensional printed elastic metamaterial rod supporting longitudinal waves. The design can be extended to elastic bending, acoustic and electromechanical media, as well as to systems with periodicity in two and three dimensions (i.e., plates and solids). Therefore, the findings of this work open avenues to investigate the bridging-coupling phenomenon in linear systems as well as to explore the properties of metamaterial isomers.

中文翻译：

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通过利用局部共振元链异构体，在线性弹性超材料中的桥联耦合现象。

弹性和声学超材料是人造结构，旨在控制和操纵通过带隙的波。具有局部共振（LR）带隙的超材料的一般带宽通常很窄，从而限制了它们在噪声和振动控制中的应用。另一方面，具有偶极共振的非线性超材料会由于桥接耦合而呈现出具有低振幅共振的宽混沌带，这仅在足够大的激发振幅下才能观察到。在这项工作中，我们表明，在偶极共振的线性超材料中也可以观察到桥接耦合现象，从而产生特殊的通带，该低通带在低频下具有低振幅共振，而与激发振幅无关。这种现象出现在带有之字形互连的经过修饰的共振元链中，并且是基于传统超材料的异构性。尽管这种改性的异构体保留了原始超材料的静态刚度和质量密度（即静态性能），但其分散行为却表现出令人感兴趣的特性（即具有负质量特征的分支和相反的基团速度重叠），从而导致总体负向有效LR带隙之间的质量决定了远程相互作用和增强的波性能。除了理论上的讨论外，还通过实验在支持纵向波的三维印刷弹性超材料杆中观察到桥接耦合。该设计可以扩展到弹性弯曲，声学和机电介质，以及具有二维和三维周期性的系统（即板和实体）。因此，这项工作的发现为研究线性系统中的桥联耦合现象以及探索超材料异构体的性质开辟了道路。