Study On Vibration Isolation And Noise Reduction Characteristics Of Phononic Crystal Plates

Phononic crystals possess the property of vibration isolation and noise reduction.Due to the internal structure of phononic crystals,when elastic waves propagate in the phononic crystals,a band gap that prevents the passage of elastic waves is generated.Using the band gap characteristics of phononic crystals to control the transmission of elastic waves has gradually become one of the research hotspots for low-frequency vibration and noise control.In this study,phononic crystals were used as the research object to widen the band gap of the phononic crystal unit cell structure,and the vibration isolation and noise reduction properties of the phononic crystal plate are studied based on the unit cell structure.In-depth analysis of the vibration and noise control of phononic crystals with band gaps below 1000 Hz is carried out.Based on the theory of phononic crystal calculation and finite element analysis,the influencing factors of the band gap of phononic crystals and the mechanism of band gap generation were analyzed.The band gap calculation of the traditional local resonance type phononiccrystal unit cell structure and the simplified equivalent model are compared,the band gap widening analysis was performed by changing the material and geometric parameters of the basic phononic crystal unit cell structure to obtain an optimized phononic crystal unit cell structure.The research shows that the band gap calculation of the local resonance type phononic crystaunit cell structure can be equivalent to the calculation of the spring oscillator model,and its calculation result is verified in the finite element method calculation.By changing the geometric parameters of the scattering body,matrix,and covering layer of the phononic crystal unit cell structure,setting reasonable parameters to expand the band gap range,an optimizedunit cell structure for calculating the vibration isolation and noise reduction characteristics of phononic crystals was obtained,and the band gap regulation law of phononic crystals was obtained.A phononic crystal unit cell structure which was used to form a plate was designed,and its isolation characteristics were studied.ln view of the vibration transmission characteristics in the plate structure,the vibration attenuation amount was analyzed when the unit cell structure was arranged in a square and rectangular pattern.With the optimal vibration attenuation effect as the target,the isolation characteristics of phononic crystal plates with various numbers of unit cell arrangements were analyzed,and the changes in the vibration attenuation characteristics of phononic crystals before and after optimization were compared.A phononic crystal plate experimental sample with the best vibration attenuation effect was fabricated to study the isolation characteristics of phononic crystals,further verifying the correctness of the simulation calculation results.Based on the analysis of the vibration isolation characteristics of the phononic crystal plate structure,the sound insulation characteristics of the phononic crystal plate structure were studied,so that the sound insulation characteristics could be effectively reflected within the band gap range.The sound insulation characteristics of the basic unit cell structure composed of a plate were compared,and the sound insulation characteristics of the optimized unit cell structure composed of a plate were analyzed,and the sound insulation enhancement effect of the optimized single cell structure composition plate was obtained.Based on the two-dimensional transverse sound insulation characteristics of the phononic crystal plate structure,a three-dimensional study of the sound insulation amount after the double-layer phononic crystal plate structure was analyzed,and the regulation law of phononic crystal noise reduction performance was obtained.