旋转单元型打孔超结构设计及减振性能研究

Design and vibration reduction characteristic of rotating unit-type perforated meta-structures

针对高速列车地板减振需求,设计了一类具有旋转单元特征的打孔弹性超结构,包括交错矩形孔四边形单元、十字矩形孔四边形单元、多边形孔三角形单元。利用Bloch理论和数值分析方法研究了元胞的带隙形成机理和参数对带隙的调控规律,探究打孔弹性超结构的低频和宽带减振应用可行性。接着,根据超结构元胞带隙分析结果建立了交错矩形孔四边形单元、十字矩形孔四边形单元、转角45°内凹多边形孔三角形单元超结构3种3D块状有限周期超结构,分析评估并改进减振块的承载性能,计算其振动传输响应。结合减振特性数值分析结果,确定最优减振块几何拓扑构型,并通过3D打印制备超结构样件,进行振动试验测试。结果表明:使用TPU(thermoplastic urethane)材料时,提出的超结构减振块均满足承载和强度要求;其中,多边形孔三角形单元超结构为最优构型,其在0~5000 Hz频率内衰减范围占比达66.9%。通过振动试验发现,相比于现有动车组减振器,多边形孔三角形单元超结构的衰减范围频率更宽,衰减幅值更大在-15 dB以上,减振效果更优,具有列车地板潜在的应用前景。

A class of perforated meta-structures with rotating units was proposed for the engineering demand of high-speed train floor vibration reduction,including a quadrilateral element with staggered rectangular holes,a quadrilateral element with cross rectangular holes and a triangular element with polygonal holes.The mechanism of bandgap and the regulation law of parameters were analyzed by using the Bloch theory and numerical simulation.Then according to the results of meta-structures band gap analysis,the 3D block meta-structure was established,including the quadrilateral element with staggered rectangular holes,the quadrilateral element with cross rectangular holes and the triangle element with 45° concave polygonal holes.The bearing performance of block meta-structure was analyzed,and the vibration responses under different configurations were calculated to determine the optimal configuration based on the numerical analysis results of the damping characteristics.Then,3D-printed samples were prepared and vibration tests were carried out to verify the vibration reduction effect of the structure.The results show that when using TPU(thermoplastic urethane) material,the proposed superstructure damping blocks all meet the requirements of bearing capacity and strength.Among them,the meta-structure with polygonal holes and the triangular element is the optimal configuration,and its attenuation range accounts for 66.9% in the frequency range of 0-5 000 Hz.Through the vibration test,it was found that,compared with the existing an EMU(electric multiple unit) absorber,the meta-structure with polygonal holes and triangular element has a wider attenuation range frequency,greater attenuation amplitude of more than-15 dB,and better vibration reduction effect,which indicates its potential application prospect of train floor.