模型参数对开口空心球超材料透射行为的影响

Effects of model parameters on the transmission property of acoustic metamaterial with split hollow sphere

为了探究模型参数对开口空心球(Split Hollow Spheres,SHS)超材料声学透射行为的作用机理,采用声学有限元方法(FEM)模拟了SHS超材料结构单元,计算球壳材料杨氏模量、泊松比、密度以及环境温度和气体密度等模型参数发生变化时的声透射谱,并推导出相应结构单元的等效模量值,最后将各参数对透射谱和等效模量的影响进行比较。结果表明:当SHS球壳材料的杨氏模量增大到2×108 Pa时,声透射谱中阻带峰值和负等效模量频带同时向高频方向移动,透射阻带宽度保持不变;球壳材料的泊松比和密度对透射阻带和负等效模量频带无明显影响;当环境温度逐渐升高时,阻带峰值和负等效模量频带同时向高频方向移动,透射阻带宽度保持不变;当气体密度逐渐增大时,阻带峰值向低频方向移动且幅值变小,透射阻带宽度变窄,同时负等效模量频带向低频方向移动且幅值变小。研究发现,在球壳的材料参数和环境因素中杨氏模量、温度和气体介质的密度对SHS结构单元透射行为的影响尤为突出。

In order to study the mechanism of the model parameters on the transmission properties of the split hollow spheres(SHS),the unit structure of SHS was simulated by the acoustic finite element method.The acoustic transmission spectra were calculated under the parameters of the Young’s modulus,the density,the Poisson’s ratio of the shell of SHS,the ambient temperature and the gas density by which the corresponding effective modulus were also deduced and compared.The results show that when the Young’s modulus of the shell increases to 2×108 Pa,the peak of the stopbands of transmission spectrum and the frequency region of negative effective modulus will move to high frequency,and the bandwidths of stopbands remains the same.The Poisson’s ratio and the density of the shell have no apparent influence on the stopbands of transmission spectrum and the frequency region of the negative effective modulus.Furthermore,when the ambient temperature increases gradually,the peak of the stopbands and the frequency region of negative effective modulus will move to high frequency with the bandwidths of stopbands unchanged.Finally,as the gas density increases gradually,the peak of the stopbands moves to the low frequency and the amplitude becomes smaller;the width of the stopbands narrows,the frequency region of the negative effective modulus moves to the low frequency and the amplitude also becomes smaller.It is found that such parameters such as Young’s modulus of the shell,ambient temperature and gas density play important roles in the transmission properties of SHS.