弹性波在非对称人工固体结构中的单向输运性质研究

Currently, the studies to unidirectional transmission of mechanical classic waves on artificial structures are mainly focused on scalar acoustic waves in fluid system. Due to the vector and wave complexity of elastic waves, the studies on unidirectional transportation of elastic waves in solid artificial structures are very lack. Whereas, to study the unidirectional transportation of elastic waves in solid artificial system can not only enrich the physics, but also has practical interesting for integrated devices of elastic waves. In this project, we will perform systematically and deeply a study on the unidirectional transportation of elastic waves in artificially asymmetrical solid structures. In specific, we will study the transporting properties of elastic waves on solid asymmetrical metasurface, exploring the mechanism of interactions between elastic waves and metasurface, obtaining the unidirectional transmission of both longitudinal waves and transversal waves; Also, we will study the one-way transportation of elastic waves in asymmetrical waveguides, analyzing the essences, and achieving the one-way mode conversion between longitudinal modes and transversal modes in waveguides; Based on the unique transportation of elastic waves in these asymmetrical solid structures, we will design the applications, such as the sing mode filter of elastic waves, single sources for transversal waves, etc. This project will be expected to bring out new concepts, to discover new phenomena and new applications, which can possess scientific significance and practical value in application.

目前关于机械经典波人工结构单向透射的研究，大多都集中于流体中的标量声波。由于固体中弹性波的矢量性和波动的复杂性，固体人工结构体系中关于弹性波的单向输运性质研究比较缺乏。研究弹性波在固体人工体系中的单向输运性质不仅具有更丰富的物理，在弹性波集成器件等应用中也具有实际意义。本项目将对弹性波在非对称固体人工结构中的单向输运性质进行系统而深入的研究。特别得，我们将研究弹性波对简单非对称超表面的输运性质，探索其相互作用机制，获得纵波和横波的单向透射；我们也将研究弹性波在非对称波导结构中的输运性质，分析其深层次的物理本质，以获得波导结构中纵波模式和横波模式之间的单向转换；然后，我们将基于弹性波在这些非对称结构中的独特输运特质，设计弹性波应用功能器件，如弹性波单一模式滤波和传输装置，弹性波单一横波源装置等等。这些研究将预期提供新概念、新现象和新应用，具有科学意义和应用价值。

随着对人工周期性结构研究的发展，应用型人工周期性结构和相应的应用器件也引起了广泛的关注，尤其具有单向传输性质的人工固体结构和功能器件是最近的研究热点。本项目深入地研究了由两个相互垂直波导结构与点缺陷共振腔组成的非对称人工固体结构的输运性质，实现了弹性波纵波、横波的单向传输与模式转换。研究了三个有效负材料参数分别来源于多重共振中的单极共振、偶极共振和四级共振的弹性波超常材料，实现了纵波和横波同时出现负折射现象。我们在刚性表面结构中设计45°棱型表面声子晶体结构，实现了赝表面波的弯曲效应与亚波长成像效应。此外，基于二维压电声子晶体结构，设计了一种工作频率、波导形状均可调复合波导管；设计了一种可调梯度声阻抗匹配层，通过调节电容来调节每层的阻抗，分析了分流电路对压电陶瓷杆纵振动的影响，理论推导了周期压电陶瓷片的色散关系，还发现负电容可以更大程度的调节有效速度，并且理论和试验证明了负电容电路。我们通过开展数值模拟、实验研究，来探寻这些机理与设计的实际应用前景。我们相信，项目中取得的这些研究结果将有助于拓展对刚性固体材料性能的探索，并将为声/弹性波集成框架下的器件设计提供一些有益的指导。