Sound Absorption Performance Simulation And Equivalent Vibration System Model Of Simple Periodic Porous Material

With the continuous development of society and the improvement of people's living standard,more and more attention has been paid to the problem of sound absorption and noise reduction.Sound absorption and noise reduction is one of the most effective methods of passive noise reduction.The finite element model and the actual structure of porous sound absorption material have some errors due to the influence of various theoretical assumptions,the boundary conditions and the uncertainty of material parameters.Based on the Helmholtz cavity theory,This paper focuses on the study of periodic porous materials with relatively simple structure.The sound absorption mechanism of porous sound absorbing material have been studied by simulating the sound absorption performance of the simple periodic porous sound-absorbing material.The acoustic module of finite element software is used to simulate the porous sound absorbing material such as perforated plate.Based on the study of the structure parameters and the key influencing factors of the sound absorption coefficient of the simple periodic porous sound absorbing material,the absorption pattern of the periodic porous sound absorbing material is obtained.At the same time,a simple periodic vibration equivalent model of porous materials is proposed.Finally,the impedance tube perforation plate of plastic material is used in the experiment to test absorption coefficient.By comparing the experimental results with simulation results,the absorption properties of simple periodic porous materials are further studied.The research includes the following components:(1)The study of the influence of different parameters on the transmission loss of a single Helmholtz resonator.The finite element software is used to establish the Helmholtz resonator model and the resonance peak value and transmission loss are simulated.The influence of various parameters on the resonant frequency and transmission loss of Helmholtz resonator is analyzed.At the same time,the relationship between resonant frequency and transmission loss of resonant cavity is examined.After the influence of the external pipe on the resonance frequency and the sound absorption coefficient of Helmholtz is discussed.The equivalent spring mass model of single Helmholtz resonator is established.(2)The study on transmission loss of multiple Helmholtz resonators.Through the finite element software to establish the model of two Helmholtz resonant cavities in parallel,the influence of the same volume and different conditions on the peak value of the transmission loss at the resonant frequency and resonant frequency is analyzed.The establishment of the two Helmholtz resonator series equivalent spring mass model and the establishment of the two Helmholtz resonator series model and simulation analysis in the cavity volume the same and different conditions on the resonant frequency and the resonant frequency of the transmission loss peak effect.The finite element model of several Helmholtz resonant cavities is established,and the model is extended to the perforated plate to test the validity of the models.(3)The experiment of sound absorption coefficient of impedance tube.This paper introduces the experimental principle of measuring the sound absorption coefficient by the standing wave tube and the related instrument.In the experiment,the influence of the cavity thickness between 10-50 mm on sound absorption coefficient is examined,and the influence of the perforation rate of the plate on sound absorption coefficient under the same conditions is also studied.The correctness of the theoretical model is verified by comparing impedance tube experimental data and simulation data.