弹性波在双原子非线性超材料中传播特性分析

Analysis of Elastic Wave Propagation Properties in Diatomic Nonlinear Metamaterials

提出一种非线性双原子声学超材料(Nonlinear Diatomic Acoustic Metamaterial,NDAM),运用多尺度法构建波动力学模型。首先对弹性波在频域下的传播机理进行研究。结果表明带隙宽度可以通过改变非线性的强度和双原子质量比来调整,同时发现不同弹簧类型影响弹性波在结构中的传播。接着进一步研究弹性波在一维链中时域尺度下的波空间谱图,研究表明NDAM系统声学模式下会产生和传统单原子系统类似的特征,即非线性效应和色散关系共同作用产生局域波现象,而双原子非线性系统光学模式下表现出较弱局域波的特性。该研究为设计新型的声学开关、声透镜、隔振器和振动与弹性波控制领域的工程应用提供一定的理论指导。

A nonlinear diatomic acoustic metamaterial(NDAM)was proposed,and a wave dynamics model was constructed by using the multi-scale method.Firstly,the elastic wave propagation mechanism in frequency domain was studied.The results show that the band-gap width can be adjusted by changing intensity of non-linearity and the diatomic mass ratio,and different spring type can influence the elastic wave propagation in the structure.Furthermore,the wave spatial-spectral properties of elastic waves in a one-dimensional chain were studied.It is shown that the interaction of nonlinearity and dispersion relation will produce acoustic-mode localization waves in both nonlinear monatomic and diatomic systems.However,optical-mode localization wave is not obvious in NDAM.This study provides a theoretical guidance for the design of new acoustic switches,acoustic lens,isolators etc.in the fields of vibration and elastic wave control.