兰姆波型柱体超构表面的研究

The cross-study of elastic wave mechanics and structural design will promote the development of new artificial structures, boost the implementation of the "Made in China 2025" and the "13th Five-Year Plan", and share the rapidly growing global market of artificial structures. Metasurface is the latest type of artificial structure materials, which is an element array with nonlinear phase-response distribution on a subwavelength-thickness "surface", which can realize wave effects such as cloaking and negative refraction that can’t be attained by traditional materials. The Lamb wave type of metasurfaces is one of the most important and complex research objects. This project proposes a new and simple type of pillared metasurface, which utilizes the scattering wave enhancement effect from the coupling of different intrinsic modes of a pillar, realizing the full control of transmitted wave’s phase and high transmission efficiency. According to the generalized Snell's law, anomalous wavefront effects such as super-resolution focusing/imaging and asymmetric transmission with a certain bandwidth can be designed and achieved. In addition, the coupling effects of multi-metasurfaces will be studied to realize the Lamb wave analogue of bound states in the continuum and Fano resonances as well as their applications in sensing, detection and waveguides. The project provides high values in both basic academic research and industrial applications.

弹性波动力学与结构设计的交叉研究，将有助于新型人工结构功能的研发，推动《中国制造2025》和十三五规划纲要的实施，并抢占快速增长的人工结构全球市场。超构表面为最新一种人工结构材料，是在亚波长厚度的“表面”上非线性分布相位响应的微单元阵列，可实现传统材料无法具备的波动效应例如隐身、负折射等。兰姆波型超构表面是其中最重要和最复杂的研究对象之一。本项目提出一种新型简单的柱体超构表面，利用柱体不同模式本征共振耦合激发的散射波增强效应，实现透射兰姆波相位完全可调性和高透射效率。根据广义斯奈尔定律，设计并实现具有带宽特性的波阵面奇异功能，例如超分辨率聚焦/成像、非对称传输等。此外，研究多元超构表面的耦合作用，实现连续束缚态和法诺共振等效应，并应用到传感检测、波导等方面。本项目同时具备较高的基础学术研究和工业应用价值。

兰姆波具有波导、感知等丰富的波动特性，已广泛应用于振动噪声评估、无损检测等领域。如何高效调控兰姆波是当前研究和应用的迫切需求。本项目提出基于柱体散射体阵列组成的超构表面来调控兰姆波波场，开展三方面研究内容：开展柱体基元对透射兰姆波的相位、振幅和带宽调控；研究柱体超构表面的波阵面调控与应用；探索多元柱体超构表面耦合效应及功能。项目开展顺利，取得了以下主要研究成果：提出了被动式柱体超构表面的相位调控和波阵面设计机理，实现了亚波长聚焦效应，发现聚焦焦斑的半峰全宽与参数（焦距/超构表面宽度）成准线性关系，且亚波长聚焦效应具有较好的抗干扰性；基于广义斯奈尔定律，设计实现了柱体超构表面的聚焦能量采集、隔波与亚波长成像效应；提出了主动式柱体超构表面的设计原理，揭示了其感知、趋肤效应和能量采集等功能机理；探索并验证了二元柱体超构表面丰富的耦合共振效应，例如法诺共振、诱导透明效应、连续介质中的束缚态等；揭示了多元柱体超构表面的耦合效应机理，提出了非对称传输、拓扑保护的局域态及其感知功能的实现方法。本项目的研究成果将有助于应用到航空航天等国家重大需求领域装备的减振降噪性能提升。