声子晶体和声超构材料的Schoch效应

It has been shown that the Schoch effect is of physical interest and owns potential application from the time of its discovery. It also has been proved that the Schoch effect was related to the evanescent wave field on the interface between a solid and liquid. In recent years, the phononic crystal and acoustic metamaterials have received great attention because of their rich and novel physical properties. The physical properties and the existence of evanescent wave on the surface of these artificial materials make it is possible to improve the development of the Schoch effect. However, the artificial material Schoch effect does not receive much attention and the physical mechanism of this kind of Schoch effect is not clear up to now. Based on the fact mentioned above, using theoretical analysis combined with numerical simulation, we will investigate the Schoch effect of the phononic crystal and acoustic metamaterial, especially, the physical mechanism of the Schoch effect. Moreover, we also study how to tune and enlarge the Schoch displacement. We hope this work can elucidate the nature of the artificial material Schoch effect and provide a help to design the acoustic device based on the Schoch effect.

自被发现起，Schoch效应就显示出有趣的物理特性和广阔的应用前景，已有的研究表明Schoch位移的出现与固-液界面的倏逝波有着密切的联系。声子晶体和声超构材料是目前科学研究的一大热点，它们丰富而新奇的物理特性及表面出现的倏逝波表明它们能促进Schoch效应的进一步发展，但目前这方面的研究报道较少，且人工材料Schoch效应产生的物理机制尚未清楚。本项目拟采用理论分析与数值模拟相结合的方法对声子晶体或声子晶体板Schoch 效应的物理机理、声超构材料或声超构材料板Schoch 效应的物理机理及如何增强声子晶体和声超构材料Schoch 效应这三个方面进行研究，期望通过这些研究能从理论上揭示声子晶体和声超构材料Schoch效应的形成机理，同时为基于Schoch效应的声波器件制作提供一定的理论指导。

Schoch效应类比于光学中的古斯-汉欣效应，它的出现与固—液界面的表面波有着密切的关系，国内外对这种现象研究多在较简单结构下的固液表面上完成。我们研究发现在有着复杂结构的二维三组元的声子晶体与水组成的表面出现了较明显的Schoch效应，由于类波导模与体模的干涉作用，导致反射波束的非镜面反射。另外，通过改变表面层包层的半径，得到Schoch位移与包层的半径相联系的变化曲线。最后通过增加表面层层数，调控两层相同核圆柱的包层半径，实现了对Schoch位移的增强，达到了对Schoch效应调控的目的。声超构材料和声超构表面是当前研究的热点，利用有限元工具，我们在超构表面及具有零折射率的声超构材料的表面也发现了较明显的Schoch效应，具体产生的原因还在研究中。除了上面的研究内容，本项目组还在兰姆波，自准直和狄拉克点方面也取得一定的研究成果。