Study On The Band Gap Characteristics Of Spiral Structure Phononic Crystal Plates

Effective suppression of vibration and noise is always the goal in the field of vibration engineering.In recent years,the proposal of locally resonant phononic crystals has provided a new idea for the development of low-frequency vibration and noise reduction technology.With the advantages of high reliability and wide frequency bandwidth,the method of using phononic crystals to achieve vibration and noise reduction has become a research hotspot in the field of vibration and noise reduction,which has attracted wide attention from academia and engineering.In this paper,a new spiral structure phononic crystal plate with low-frequency vibration reduction characteristics is proposed,and its band gap characteristics are systematically and thoroughly studied in combination with band structure,vibration modes and transmission characteristics.The main contents and conclusions of this paper are as follows:Firstly,the method for calculating band gap characteristics of phononic crystal plates based on finite element method is analyzed,and the coupling effect of plate wave modes and local resonance modes is systematically studied in combination with band structure and vibration modes;secondly,the influence of substrates' and local resonance units' parameters on bending wave band gap characteristics is explored,and it is found that choosing materials with lower Young's modulus as the substrate materials,thinning substrates,appropriate reducing the lattice constants,choosing materials with higher density as cylinders,increasing the height of cylinders,and appropriate reducing the width of spiral structure are conducive to broadening the bending wave band gap;then,the influence of damping on transmission characteristics is explored,and it is found that both substrate damping and spiral structure damping can suppress the resonance peak of substrate;finally,a finite periodic phononic crystal plate structure composed of local resonance units with gradient changed spiral angle and cylinder height is proposed,which can further broaden the band gap of low-frequency bending wave.The principle is that the band gap of each resonant unit is superimposed,and the nearer the unit is to the response pickup point,the more obvious the effect on the whole finite periodic structure is.By systematically studying the band gap characteristics of spiral structurephononic crystal plates,a phononic crystal plate with good low-frequency vibration reduction performance is finally designed in this paper.The band gap of the structure is38.0-289.7 Hz and the normalized bandwidth is as high as 1.536.The transmission characteristics of the structure can be further optimized after using the resonance unit with gradient decreasing spiral angle.The band gap range can be changed to 36-500 Hz,which almost covers the low-frequency range,thus effectively suppressing the low-frequency vibration.The research results of this paper can provide guidance for the design of low-frequency vibration and noise reduction structures,and have great significance in the field of low-frequency vibration and noise reduction.