Analysis On Sound Absorption Performance Of Honeycomb Sandwich Structure With Built-in Acoustic Damping

Honeycomb sandwich structure,which has a unique advantages of light weight,large specific strength and stiffness and the characteristics of anti-instability,anti-fatigue,heat insulation,sound insulation,vibration damping and so on,is widely used in aviation.The traditional honeycomb sandwich structure is dominated by hexagonal honeycomb,Now we try using circular honeycomb to instead of hexagonal honeycomb for forming circular honeycomb sandwich structure,and take it as the research object.Because there are large experimental research on stamping of circular honeycomb sandwich structure and relatively few research of in-plane mechanical properties,so we choose the latter as the starting point.So the in-plane mechanical parameters of hexagonal and circular honeycomb structures are analyzed,and then their sound absorption properties are studied.Firstly,the in-plane mechanical parameters of hexagonal and circular honeycomb structures are compared and analyzed.In this paper,the equivalent principle is used to analyze the honeycomb structure.According to analyzing the equivalent elastic modulus,equivalent crushing strength and the equivalent yield strength of the three main parameters,we can find that when increase the honeycomb wall thickness,the elastic modulus and strength of hexagonal honeycomb structure are less than close circular honeycomb structure,so the results show that the close honeycomb structure has the advantage of in-plane mechanical properties.Secondly,the sound absorption performance of hexagonal and circular honeycomb sandwich structures is analyzed.In this paper,the acoustic transmission method is adopted to solve the incident wave and transmission wave when sound wave pass through the honeycomb sandwich structure,then the incident acoustic power and transmitted acoustic power are calculated,which can used to calculate the theoretical calculation formula of sound absorption coefficient.It can be concluded that sound absorption effect of honeycomb sandwich structure is not quit ideal.So the results show that the traditional honeycomb sandwich structure has good sound insulation performance and poor sound absorption performance.In order to improve the sound absorption performance of honeycomb sandwich structure,the upper surface of honeycomb sandwich structure is microperforated to increase the sound absorption effect.Further,the acoustic damping of the microperforated plate is embedded in the honeycomb core,by using the acoustoelectric analogy method we can calculate itssound absorption coefficient and using comsol simulation results can validate the correctness of the theoretical calculation.Finally,the honeycomb sandwich structure with acosutic damping is analyzed and verified.Based on the verified sound absorption coefficient formula of honeycomb sandwich structure with built-in microperforated plate,we can analyze the influence of structural parameters for sound absorption coefficient.The results showed that the sound absorption effect of built-in microperforated plate was significantly improved when the perforation diameter was quite small.When the thin plate is placed in the honeycomb core and a certain height ratio is formed,the sound absorption bandwidth of honeycomb sandwich structure is widened and the sound absorption coefficient is increased,which indicates that the built-in thin plate can also improve the sound absorption effect of honeycomb sandwich structure.Then,the influence of the structure parameters on the sound absorption coefficient is analyzed when there are double layer microperforated board built in the honeycomb core.Finally,according to comparing the sound damping type,the honeycomb sandwich structure which has better sound absorption effect with built-in acoustic damping is obtained.