Study On Structure Optimization And Manufacturing Technology Of Multi-scale High Efficiency Acoustic Absorbing Perforated Plate

Micro perforated plate absorber has the advantages of low pollution,high structural strength and strong corrosion resistance,it is widely used in many fields,such as buildings,automobiles,submarines,aircraft and so on,it is the most widely used sound absorption structure nowadays.However,due to its small sound absorption bandwidth and poor sound absorption effect in low frequency band,the cavity behind the plate leads to a larger space needed which affects its widespread application.So,improve the sound absorption bandwidth and low-frequency sound absorption performance of Micro-Perforated plates without increase the volume of the structure is the main direction of current research.The sound absorption performance of oil-slurry coupled micro-perforated plate structure was investigated by experimental.The oil-slurry material was added into the metal punched plate under normal temperature conditions to produce oil-slurry coupled micro-perforated plate with different structural parameters,the sound absorption coefficient was measured by the impedance tube transfer function method and compared with the traditional machined micro-perforated plate.The results show that the oil-slurry coupled micro-perforated plate can move the sound absorption coefficient curve to the low frequency direction under the condition of larger aperture and larger perforation rate.When the pore size or perforation rate is too small,there is no significant difference between the performance of oil-sludge coupled micro-perforated plate and conventional micro-perforated plate.Oil-Sludge is extremely sensitive to temperature.It begins to soften at 50℃ and cannot adhere to the punched plate at above 60℃.Therefore,the oil-sludge coupled micro-perforated plate could not be used under high temperature conditions such as exhaust muffler of motor vehicles.The theoretical sound absorption performance of ideal rigid micro-perforated plate is determined by its structural parameters.The main structural parameters are perforation rate,perforation diameter,cavity depth behind the plate and thickness of perforated plate.The effect of structural parameters on the sound absorption performance of micro-perforated plate was studied by MATLAB.The oil-slurry coupled micro-perforated panels with the same structural parameters were prepared and compared with the numerical results.The results show that the influence of parameters of sludge-coupled micro-perforated plate on its sound absorption performance is basically the same as that of ideal rigid micro-perforated plate,which indicates that the sludge-coupled micro-perforated plate is similar to the ideal perforated plate,and the change trend of sound absorption performance is the same,but the absorption performance has been greatly improved.The analysis shows that the depth of cavity behind the plate can independently and clearly affect the sound absorption performance of the micro-perforated plate.The perforation rate,diameter and thickness of the perforated plate can not have a clear impact on the sound absorption performance of the perforated plate alone.Introduce two new methods which are simple and low cost to improve the sound absorption performance of micro-perforated plate,the experimental results show that changing the micro pore distribution of micro perforated panels has a great influence on the sound absorption performance of micro perforated plate.The perforated rib-plate coupled micro-perforated plate could be analogous to the double-layer perforated plate.The first absorption coefficient curve wave peak increases the low-frequency absorption coefficient,the second peak is consistent with the peak value of the single-layer micro-perforated plate absorption coefficient curve,and the absorption bandwidth will be greatly reduced.The experimental results prove the correctness of the theoretical analysis.