拓扑超材料中弹性波模式分离及能量聚集

MODE SEPARATION AND ENERGY LOCALIZATION OF ELASTIC WAVES IN TOPOLOGICAL METAMATERIALS

在凝聚态物理系统中的拓扑超材料,由于其反常的物理现象,在信息处理与能量应用方面展现出巨大的潜力.近些年来,受凝聚态物理中拓扑现象的启发,经典波动系统中的力学拓扑现象受到越来越多的关注.弹性波作为振动的重要载体,广泛存在于工程与自然环境中.作为一种矢量波,弹性波相对于声波与电磁波等标量波展现出更复杂的多分量传输特性,在调控与应用方面存在诸多困难.在本研究中,将以拓扑超材料为基础,围绕弹性波分解与力学应用展开.首先利用设计的声子晶体实现了双重狄拉克锥,并通过在声子晶体中引入几何扰动,实现了弹性波面内和面外模式的拓扑相分离;通过不同拓扑相的组合,构造了具有不同波传输特性的拓扑边界态,实现了弹性波面内和面外模式的分离;进一步地,基于耳语回廊(whispering gallery)模式引发的能量局域化,弹性波面内和面外分量的能量实现了分区域聚集,为振动能量高效俘获提供了思路.弹性波模式分离及其引发的能量聚集均采用实验进行了验证.阐明了拓扑超材料在弹性波分量调控与能量应用中蕴含巨大潜力,对振动信号处理与能量俘获等应用具有积极意义.

Topological metamaterials,a frontier in condensed matter physics,have shown tremendous potential for diverse applications in information processing and energy utilization,owing to their remarkable physical phenomena.In recent years,inspired by the insights from topological phenomena in condensed matter physics,there has been a growing interest in mechanical topological phenomena in classical wave systems.Elastic waves,pivotal as carriers of vibration,permeate both engineered structures and natural environments.As vector waves,elastic waves exhibit more complex multi-component transmission characteristics compared to scalar waves such as acoustic waves and electromagnetic waves,which pose numerous challenges in wave manipulation and mechanical applications.In this study,we focus on the exploration of elastic wave decomposition and mechanical applications based on topological valley metamaterials.Firstly,the phononic crystals with double Dirac cones are designed to realize separated topological phases of in-plane(IP)and out-of-plane modes(OP)through geometric perturbations.Through the combination of different topological phases,the topological edge states with different wave transmission properties are constructed.Consequently,the inplane and out-of-plane components of elastic waves are separated within the fabricated phononic crystal plate.Furthermore,drawing inspiration from the topological whispering gallery phenomenon renowned for its high energy density,the potential application of mode separation of elastic waves in energy localization are investigated.Based on the energy localization achieved by the topological whispering gallery mode,the energy of in-plane and out-of-plane waves is concentrated in different regions,thereby providing ideas for efficient vibrational energy harvesting.Experimental verification is conducted to verify the observed mode separation phenomena and the localized energy behavior of elastic waves.This study illustrates the great potential of topological valley metamaterials in wave manipulation and energy utilization.These advancements hold significant promise for various mechanical applications,including vibration signal processing and energy harvesting,thereby underscoring their positive significance in advancing engineering and scientific frontiers.