Bandgap And Sound Absorption Properties Of Local Resonance Acoustic Metamaterials

Phononic crystals and acoustic metamaterials are artificially synthesized composite materials that can regulate the band structure of vibrational waves.Due to the particularity of its internal microstructure,acoustic metamaterials exhibit unique properties such as negative effective mass density and negative bulk modulus,leading to abnormal band structure and sound absorption performance of the structure.In recent years,research on metamaterials has attracted widespread attention.Acoustic metamaterials can effectively deal with noise problems.Among them,the research on sound-absorbing materials has become a hot spot.In this paper,the transfer function method is used to analyze and study the vibration characteristics of the local resonant material structure.A one-dimensional dual-resonant mass spring oscillator model is established.The effective mass of the model and the recursive method of the resonant periodic structure are obtained by calculation and simulation with Matlab software.The band gap formation mechanism of the finite periodic structure was determined by the expression of the transfer function,and the band gap diagram of the structure was obtained.Compared with the results obtained by the traditional vibration method,the accuracy of the band gap calculated by the transfer function was verified.At the same time,by analyzing the relationship between the number of systems and the poles of the system,the transfer function method can be used to change the band gap frequency range of the system by the number of primitive cells.In the experiment,rubber and two types of metal powder were respectively bonded and cured by epoxy resin to obtain a composite metamaterial with a certain shape.The standing wave tube method was used to determine the sound absorption coefficient of the prepared material,and the obtained tungsten rubber composite material has good sound absorption performance.Experiments show that reducing the particle size of the metal powder reduces the sound absorption performance of the composite material accordingly;through the study of the sound absorption performance of the material thickness,the optimal material preparation thickness is 10mm;Tungsten powder and rubber powder mixed ratio materials are tested experimentally,and the sound absorption performance is best when the ratio of the two is 1:1.The results show that the metal-rubber resonance sound-absorbing material proposed in the study has highly efficient sound-absorbing performance,and further promotes the application process of the resonance sound-absorbing material.