Study On Acoustic And Vibration Characteristics Of Phononic Crystal Sandwich Plates

Grid sandwich plate is widely used in aerospace,vehicle,ship and other fields because of its high specific strength and high specific modulus,and its vibration and noise problems have been widely concerned.As a kind of man-made periodic structure,phononic crystal has the band gap characteristic of prohibiting elastic wave propagation,and has a good application prospect in vibration and noise control.In this paper,the phononic crystal structure is introduced into the grid sandwich structure to study the band gap characteristics,transmission characteristics and sound insulation characteristics of the phononic crystal sandwich structure.In this paper,the equivalent theory of grid sandwich plate and the research status of phononic crystal theory are reviewed in detail,and the basic theory of phononic crystal and the calculation method of band gap are introduced.At the same time,three common equivalent theories of grid sandwich panel are introduced in detail,and the sound insulation theory of structure is introduced.On the basis of the above theory,this paper mainly carried out the following work.Firstly,Hoff theory is used to simplify the sandwich plate structure,and the cylindrical vibrator is simplified as a spring mass system.The band gap characteristics of the simplified model are theoretically deduced,and the correctness of the calculation is verified by comparing the finite element results.Through the vibration mode corresponding to the typical point on the band gap characteristic curve,the band gap mechanism is analyzed.The double band gap phononic grid sandwich plate structure is designed,and its band gap mechanism is simply studied.Furthermore,the influences of structural material parameters and geometric parameters on the band gap and transfer characteristics of the sandwich plate structure are analyzed.The results show that the structure has a good suppression of vibration in the band gap range.With the change of material parameters and geometric parameters,the band gap range will change accordingly,which will affect the band gap characteristics and vibration transmission characteristics of the structure.Based on the finite element method,the sound insulation characteristics of the structure are analyzed,and the sound insulation characteristics of the structure are verified.At the same time,the multi frequency and wide frequency sound insulation performance of the structure is designed.The sound insulation characteristics of the structure are tested and verified by experiment,and the sound insulation effect is compared with the common damping coating on the market.The results show that in the band gap range,the sound insulation performance of the phononic crystal sandwich panel is better than that of the plate which had the damping coating of the same quality.