Department of Mechanical Engineering, The University of Akron, Akron, OH, 44325-3903, USA.
Sci Rep. 2017 Jul 24;7(1):6226. doi: 10.1038/s41598-017-05526-3.
Unidirectional/asymmetric transmission of acoustic/elastic waves has recently been realized by linear structures. Research related to unidirectionality of wave propagation has received intense attention due to potentially transformative and unique wave control applications. However, asymmetric transmission performance in existing devices usually occurs only in a narrow frequency band, and the asymmetric frequencies are always within ultrasound range (above 20 kHz). In this work, we design and propose a linear diatomic elastic metamaterial using dual-resonator concept to obtain large asymmetric elastic wave transmission in multiple low frequency bands. All of these frequency bands can be theoretically predicted to realize one-way wave propagation along different directions of transmission. The mechanisms of multiple asymmetric transmission bands are theoretically investigated and numerically verified by both analytical lattice and continuum models. Dynamic responses of the proposed system in the broadband asymmetric transmission bands are explored and analyzed in time and frequency domains. The effect of damping on the asymmetric wave transmission is further discussed. Excellent agreements between theoretical results and numerical verification are obtained.
声/弹性波的单向/非对称传输最近已通过线性结构实现。由于潜在的变革性和独特的波控应用，与波传播的非对称性相关的研究受到了极大关注。然而，现有器件中的非对称传输性能通常仅在较窄的频带内发生，且非对称频率始终在超声范围内（高于 20 kHz）。在这项工作中，我们设计并提出了一种使用双谐振器概念的线性双原子弹性超材料，以在多个低频带中获得大的非对称弹性波传输。所有这些频带都可以通过理论预测来实现沿不同传输方向的单向波传播。通过解析晶格和连续体模型，从理论上研究和数值验证了多个非对称传输带的机制。在时间和频率域中探讨和分析了所提出系统在宽带非对称传输带中的动态响应。进一步讨论了阻尼对非对称波传输的影响。理论结果和数值验证之间取得了极好的一致性。
