散射体特征对隔声超材料性能的影响

Influence of the Characteristics of Scatterers on the Performance of Sound Insulation Metamaterials

为研究应用于轨道车辆降噪的声学超材料,在分析两种晶体结构的基础上,从密度角度出发研究散射体特征对声学超材料性能的影响。建立三维三组元金刚石声子晶体模型,通过控制变量法在控制基体材料和包裹层材料参数一致的情况下,针对散射体密度进行梯度递增,以此求解并绘制不同散射体密度条件下三维三组元金刚石声子晶体能带结构图。结果表明:三维三组元金刚石声子晶体的带隙作用频率在6725.77 Hz~11632.62 Hz之间,基本与高速列车噪声覆盖范围重合;带隙随着散射体密度的增加,带隙起始频率和带隙终止频率均从高频开始降低,二者降低幅度有所区别。带隙宽度会随散射体密度的增加而增加,拟合带隙随散射体密度变化的曲线后发现,三维三组元金刚石声子晶体的带隙宽度随密度的变化曲线更倾向于3阶函数。该结构的扩展结构可应用于轨道车辆地板层、高速铁路沿线声屏障等有降噪需求的部位。

Acoustic metamaterials applied for noise reduction in rail vehicles are studied.Based on the analysis of two crystal structures,the influence of density of the scatterers on the performance of acoustic metamaterials is studied.A threedimensional and three-element phononic crystal model of the diamond is established and solved by using the controlled variable method under the condition that the parameters of the substrate material and the coating material are the same and the density of the scatterer increases gradiently.The three-dimensional energy band structure diagram of the three-element diamond phononic crystal is plotted for different densities of the scatterer.The results show that the band gap frequency range of the three-dimensional and three-eelement diamond phononic crystal is in the frequecy range of 6725.77 Hz-11632.62 Hz,which basically coincides with the frequency range covered by high-speed train noise.As the density of the scatterer increases,both the band gap starting frequency and the band gap ending frequency decrease from high frequencies,but the reduction extents of the two frequencies are different.The band gap width increases with the increase of the density of the scatterer.After fitting the curve of the change of the band gap with the density of the scatterer,it is found that the curve of the band gap width of the three-dimensional and three-element diamond phononic crystal vs.the density of the scatterer more inclines to the third-order polynomial function.The extended structure of the structure can be applied to the floor of rail vehicles,sound barriers along high-speed railways and other parts that require noise reduction.