周期结构波阻板的带隙特性研究

Study on band gap characteristics of periodic structural wave impeding block

波阻板(WIB)常被埋置于动力机器、轨道及路基下方以减小人工振源产生的振动。但波阻板受土层截止频率的制约(只有振源频率低于该截止频率时,波阻板才能起到隔振效果)隔振频带较窄,而振源频率成分往往复杂,低、中、高频均有分布。为克服波阻板隔振频率依赖于土层截止频率的技术缺陷,根据声子晶体原理,提出一种周期结构波阻板(Periodic Structural WIB,PSWIB)。理论和数值计算均表明:周期结构波阻板具有带隙特性,有限周期结构波阻板所得衰减区与无限周期波阻板带隙范围一致,振动衰减区内最大振幅衰减分别可达47dB和65dB。相比传统波阻板,周期结构波阻板突破了土层截止频率的制约,并且可根据振源特性设计其组成参数实现对目标频率振动的隔离。

Wave impeding block(WIB)is usually buried under power machine,track and roadbed to reduce the vibration caused by artificial vibration source.However,wave impeding block is restricted by the cut-off frequency of the soil layer.The vibration isolation frequency band is narrow,and the vibration source frequency components are often complex,with low,medium and high frequencies distributed(only when the vibration source frequency is lower than this cut-off frequency,the wave impeding block can have the vibration isolation effect).In order to overcome the technical defect that the vibration isolation frequency of wave impeding block depends on the cut-off frequency of soil layer,a periodic structural wave impeding block(PSWIB)is proposed according to the principle of phononic crystal.Theoretical and numerical calculations show that the periodic structure WIB has band gap characteristics.The attenuation range of the finite PSWIB is consistent with that of the infinite PSWIB,and the maximum amplitude attenuation in the vibration attenuation region can reach 47dB and 65dB respectively.Compared with the traditional WIB,the PSWIB breaks through the restriction of cut-off frequency of soil layer.According to the characteristics of vibration source,the composition parameter of PSWIB can be designed to isolate the vibration with the target frequency.