Design And Manufacture Of Piezoelectric Transducer Mechanism Based On Noise Reduction Characteristics Of Low-band Thin Film Acoustic Metamaterial

Acoustic metamaterials are periodic artificial composites materials that composed of different elastic modulus and mass density,which have properties not found in natural materials.With the deepening of theoretical research,acoustic metamaterials are gradually moving into practical applications.In this thesis,the noise reduction characteristics of thin film acoustic metamaterials in the low frequency range are analyzed,and a new piezoelectric transducer mechanism is designed.The new piezoelectric transducing mechanism can realize the conversion of noise energy into electric energy,so that the application prospect of renewable energy become more broad,and the energy substitution is truly realized while reducing environmental pollution.The effects of material parameters and structural parameters of the film-type acoustic metamaterial on the noise reduction performance were simulated.Based on the existing theory of noise isolation and absorption,the effects of different parameter changes on the noise reduction performance of metamaterials were calculated using COMSOL Multiphysics simulation software.The advantages of changing the film type acoustic metamaterial parameters in low frequency sound absorption and sound insulation were discussed.The results indicated: locally reducing the quality of hollow mass could increase the sound absorption coefficient of metamaterial;The change of prestress has a weak influence on the sound absorption coefficient;Reducing the center area of the film in contact with sound waves could increases the absorption of sound waves at lower frequencies;When the film thickness is increased,the maximum sound absorption coefficient value is decreased,and the sound absorption frequency point corresponding to the peak of the sound absorption curve is also moved to the high frequency.Increasing the number of metamaterial units or the number of film layers can increase the average sound absorption coefficient and the average sound insulation.Based on the simulation results and actual experimental conditions,a film-type acoustic metamaterial structure composed of a support frame,an elastic film and a hollow mass is finally designed.The Film-type acoustic metamaterial test samples 1 and 2 were processed and fabricated,and the sound absorption and sound insulation performance of the standing wave tube was tested and compared with the simulation results.It was found that the sample 1 had the smallest sound insulation at a frequency of 420 Hz,and the simulation results showed that the sound insulation amount was the smallest at a frequency of 431 Hz.The experimental results show that the sound insulation and sound absorption coefficient curves of samples 1 and 2 are similar to the simulation results,and the theory is basically consistent with the actual situation.The standing wave tube experiment demonstrates that the film-type acoustic metamaterial has superiority to the common sound insulation structure in low frequency noise reduction.A new piezoelectric transducer mechanism was designed and manufactured to realize the collection and conversion of noise energy by thin film acoustic metamaterials.The film-type acoustic metamaterial absorbs the white noise acoustic wave energy in the frequency range of 0-1000 Hz,especially when the film and the hollow mass reach resonance,the noise energy is converted into electric energy by the novel piezoelectric transducer mechanism,and the experimental results show that a small current of 0.1 ?A is successfully converted.The experimental data verified the operability of the new piezoelectric transducer mechanism and basically realized the effective use of renewable energy.