面向非互易波调控的周期时变弹性材料设计与力学表征

Spatiotemporal elastic mediums, whose elasticity and inertial are modulated periodically in both space and time, are able to induce the non-reciprocal wave propagation, which is expected to bring disruptive technological concepts in wave-controlling areas including confidential communication, noise and vibration suppression, and energy harvesting. However, there are still some critical issues that need to be resolved. These include that it is still unclear how the non-reciprocity is determined by the spatiotemporal distribution of properties, as well as unclear how to design artificially and characterize time-varying elastic mediums. To resolve these issues, we plan to establish the systematic methods of the microstructure design, characterization, fabrication, and experiment of spatiotemporal elastic mediums in order to implement the control over non-reciprocal wave propagation. To this end, non-reciprocal wave phenomenon in the complex spatiotemporal arrangement of material properties will be studied in this research project. Based on the multi-body models, artificial materials with time-varying elasticity and/or inertial will be designed. Then we develop the dynamic homogenization method, which would help to bridge the connection between the overall time-varying properties and microstructural parameters. Finally, the optimal design, fabrication, and experiment measurement of time-varying materials towards non-reciprocal wave control will be conducted.

周期时变弹性介质具有周期性时空调制的弹性和惯性属性，可打破互易性原理实现弹性波单向输运，有望在保密通讯、减振降噪、能量采集等应用领域产生新的技术机理。但目前研究还存在一些关键性问题亟待解决，如时空材料属性对非互易波传播的内在调控规律不清楚，时变弹性介质的设计实现与力学表征等方法还没有系统建立，阻碍了非互易弹性波调控的实现。为此，项目以时变介质实现非互易弹性波传播为研究目标，通过研究时变弹性介质的微结构设计、动态力学表征及制备和实验方法，系统给出时变弹性介质的设计理论。为此，将首先研究多自由度时空结构对非互易波传播的内在调控规律，进而基于微多体模型系统发展出一套具有时变质量/时变模量属性的材料体系，并研究能够预测时变属性的动态均质化方法，从中揭示时变属性与微结构参数的量化关系，最后通过优化设计、制备和测试研究时变材料的非互易弹性波调控功能。

项目面向非互易弹性波调控，系统研究了周期时变弹性材料的设计方法，及其对非互易波传播、受拓扑保护能量输运和手性模态转换的应用机理。取得的主要研究成果有：提出了动态机构超材料概念，系统给出了时变质量、时变模量和时变阻尼的设计方法，揭示了材料属性时变调制引起的非互易波传播行为；在一维周期系统通过刚度参数的慢速时间调制构造出人工合成维度，发现了具有大带隙陈数的弹性波拓扑相性质；在耦合陀螺转子的点阵结构中，实现了具有手性惯性耦合效应的弹性陀螺介质，从中发现了Rayleigh表面波的非互易现象；将时变机构引入非厄米机械系统，实现了二维参数空间环绕奇异点的时驱动态演化，揭示了手性模态转换现象；提出时变质量引起的非厄米奇异点行为，揭示了奇异点附近对系统参数微扰的高灵敏传感机理。上述研究成果在JMPS、IJSS等国际知名期刊发表SCI收录论文12篇，在波动能量定向输运和高灵敏传感等领域具有潜在应用价值。