Mechanical metamaterials can be used to control elastic waves, but it is challenging to obtain multiple or ultrawide bandgaps. A one-dimensional simple periodic system with multi-resonator unit cells can achieve multiple locally resonant bandgaps. A unit cell that comprises multiple cells is called a hybrid unit cell. Two different metamaterials with hybrid unit cells are proposed to achieve a wider coupled bandgap. The first type of metamaterial with a hybrid unit cell comprises two simple cells that have different bandgaps connected by a spring. A new Bragg bandgap appears near the locally resonant bandgaps. By adjusting the spring stiffness, these two types of bandgaps can be coupled to achieve an ultrawide coupled bandgap in a lower frequency range. The second type of metamaterial with a hybrid unit cell comprises two different sub-periodic systems. The bandgaps can be combined to achieve a wider bandgap. With this hybrid periodic system, a wider bandgap can be achieved by designing sub-periodic systems with different bandgaps. In addition, the transmission of a finite periodic system is calculated by the transfer-coefficient method, and the results show that elastic waves can be suppressed in wider frequency range in hybrid periodic systems. This paper provides new ways to design metamaterials with wider and lower bandgaps, which can be used for wide and low-frequency vibration isolation in engineering applications.

中文翻译：

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具有多个谐振器的混合周期系统中的超宽耦合带隙

机械超材料可用于控制弹性波，但获得多个或超宽带隙具有挑战性。具有多谐振器单元的一维简单周期系统可以实现多个局部谐振带隙。由多个单元组成的单元称为混合单元。提出了两种不同的具有混合晶胞的超材料来实现更宽的耦合带隙。具有混合晶胞的第一种超材料包括两个具有不同带隙的简单晶胞，它们通过弹簧连接。新的布拉格带隙出现在局部共振带隙附近。通过调整弹簧刚度，可以将这两种带隙耦合起来，在较低的频率范围内实现超宽耦合带隙。具有混合晶胞的第二种超材料包括两个不同的亚周期系统。可以组合带隙以实现更宽的带隙。通过这种混合周期系统，可以通过设计具有不同带隙的亚周期系统来实现更宽的带隙。此外，通过传递系数法计算了有限周期系统的传输，结果表明，混合周期系统可以在更宽的频率范围内抑制弹性波。本文提供了设计具有更宽和更低带隙的超材料的新方法，可用于工程应用中的宽低频隔振。通过设计具有不同带隙的亚周期系统可以实现更宽的带隙。此外，通过传递系数法计算了有限周期系统的传输，结果表明，混合周期系统可以在更宽的频率范围内抑制弹性波。本文提供了设计具有更宽和更低带隙的超材料的新方法，可用于工程应用中的宽低频隔振。通过设计具有不同带隙的亚周期系统可以实现更宽的带隙。此外，通过传递系数法计算了有限周期系统的传输，结果表明，混合周期系统可以在更宽的频率范围内抑制弹性波。本文提供了设计具有更宽和更低带隙的超材料的新方法，可用于工程应用中的宽低频隔振。