三维局域共振型声子晶体低频带隙特性研究

摘要

A kind of three-dimensional local resonance phononic crystal structure was proposed.By FEM calculation,low frequency bandgap characteristic,multiple vibration coupling mechanism and corresponding influence factors of geometric parameters were analyzed.Results show that this kind of structure can open ultra-low frequency bandgap under 50 Hz and critical factor is the vibration coupling effect between the matrix material and cylindrical harmonic oscillator.The more vibration displacement of lower surface on cylindrical harmonic oscillator is,the wider bandgap is.Density of middle oblique bar has no effect on the lower edge of bandgap,but makes the upper edge of bandgap move to the higher frequency range,and hence results in the change of bandgap.Length of middle oblique S2 section and angle of S1 section are the most important factor in bandgap.This study enriches the design and the equivalent model of three-dimensional phononic crystal frequency structure,which possesses a certain guiding value in engineering application.%提出了一种三维局域共振型声子晶体结构,通过有限元仿真分析了该结构的低频带隙特性和多重振动耦合机理,继而研究了几何参数的影响因素.结果表明,该结构可以打开50 Hz以下的超低频带隙,其中基体材料和圆柱谐振子的振动耦合是带隙打开的关键,圆柱谐振子的下表面的振动位移越大,越容易打开带隙.中间层斜条部分密度对于带隙的下边界几乎没有影响,但是可使带隙的上边界往高频移动,带隙宽度变大.导致带隙变化的关键因素是中间层S2部分的长度和S1部分的角度.本工作丰富了三维声子晶体低频结构设计和等效模型研究,在工程实践中具有一定的指导价值.