Study On Sound Absorption Design Of Closed Circular Honeycomb Sandwich Structure

Honeycomb sandwich structure is widely used in aerospace,marine,automotive,building materials and other fields because of its light weight and high mechanical strength,high stiffness ratio,impact resistance and other excellent mechanical properties.Considering that the working environment of the structure is often accompanied by noise and vibration,excessive noise will not only cause discomfort to workers and passengers,but also affect the service life of the equipment.Compared with the hexagonal honeycomb core structure,the circular honeycomb has the advantages of less core material consumption,higher strength ratio,higher bearing capacity,and avoidance of stress concentration at the polygonal hole and corners.In this paper,the sound insulation of circular honeycomb sandwic h panel structure,the sound absorption of honeycomb sandwich structure with single-sided perforated plate,and the sound absorption of honeycomb sandwich structure with double-sided perforated plates are studied.First,the sound insulation properties of a circular honeycomb sandwich panel structure were analyzed.The equivalent theory of sandwich plate is used to calculate the equivalent mechanical parameters of the circular honeycomb sandwich layer,and the sound insulation of the sandwich plate structure is calculated based on the equivalent mechanical parameters.The theoretical model calculation is verified by the multi-physics coupled finite element software COMSOL.Finally,the influences of honeycomb core radius,layer core wall thickness,and struc tural materials on structural sound insulation were discussed.The results show that under the simple boundary conditions of four sides,the sound insulation performance of the structural plate decreases,as the increase of the radius of the circular honeycomb cell,the sound insulation performance of the structural panel decreases,as the radius of the circular honeycomb cell increases.and the sound insulation valley moves to a low frequency.In addition,if the structural materials are different and structural sound insulation is different.Copper and steel structural panels have better sound insulation than aluminum structures.Secondly,the sound absorption performance of honeycomb sandwich structure with single-sided micro-perforated plate was analyzed.Acoustic wave theory was used to calculate the relative acoustic impedance of the micro-perforated plate and the circular honeycomb sandwich cell tube.The sound absorption coefficient of the structural plate was solved by the acoustic and electrical analogy method and the influence of the diameter of the perforation of the panel,the perforation rate,the thickness of the panel,and the cell radius of the sandwich cell on the sound absorption performance of the circular honeycomb structural panel was ana lyzed.The results show that: Compared with the change of cell core radius,the perforation plate perforation rate,perforation diameter,perforated plate thickness,honeycomb core wall thickness changes have more significant impact on the sound absorption performance of the structural plate,therefore,in engineering applications,the influence of the cell core cell radius on the sound absorption performance can be almost ignored.Finally,the effectiveness and reliability of the theoretical model are verified by impedance tube test.At last,the bidirectional sound absorption performance of honeycomb sandwich structure with double-sided perforated plates was analyzed.Based on the obtained relative acoustic impedance of the perforated plate and the layer core,the transfer matrix method was used to solve the sound absorption coefficient of the structural plate.With the aid of the numerical analysis software MATLAB,the genetic algorithm was used to optimize the bidirectional sound absorption performance by optimizing the plate thickness,perforation diameter,perforation rate,and honeycomb cell radius of the upper and lower panels.The correctness of the theoretical optimization results was verified by the acoustic module in COMSOL software.