Simulation Design Of Thin-film Acoustic Metamaterial

With the rapid pace of modern life,noise to some extent is inevitable and yet extremely harmful.In particular,due to its characteristic properties,thelow-frequency noise possesseshigh penetrating power,which makes it difficult for traditional materials to effectively isolate or absorb low-frequency noise,and hence it becomes a pernicious form of environmental pollution.To reduce the harm of low-frequency noise,new materials are desired.To this end,the lightweight ultra-thin low-frequency sound insulation materialshave been the research focus in the field of sound insulation and noise reduction.Acoustics metamaterials regarded as a kind of artificial acoustics material with sub-wavelength structure have characteristic properties superior to the natural materials,triggering relevant theoretical and applied in recent years.While,the research and design of various acoustic devices based on acoustic metamaterials,such as vibration and noise reduction structure,have become research focus.It can be said that the emergence of thin film-type acoustic metamaterials has made up for the shortcomings of traditional linear sound insulation materials on dealing with low-frequency noise problems,and they have obvious advantages on lightweight low-frequency sound insulation.In this paper,the mechanism of low frequency noise reduction has been studied systematically,and a kind of thin film type acoustic metamaterials expected to be well applied in practice has been designed.The research contents are as follows:(1)Starting from the theory of acoustic propagation,the reflection,transmission and absorption coefficients of sound waves on the surface of sound insulation are analyzed.The mechanism of the sound insulation is analyzed theoretically,and the evaluation index of sound insulation performance is given.Based on the principle of energy in structural mechanics,the distribution of strain energy in the thin film structure under deformation is analyzed,and the sound insulation properties of the film materials are stated,which provides the basis for the analysis of the sound insulation mechanism of the thin film acoustic materials.(2)The finite element simulation method for the calculation of sound insulation of thin film acoustic material is introduced.Based on the theoretical model of thin film acoustic metamaterials and the finite element method,the acoustic-solid coupled model of metamaterials is established with the aid of the commercial finite element software COMSOL.The sound insulation performance of thin film acoustic material under the stimulation from acoustic source at different frequencies(100Hz-1200Hz)is analyzed,and the effectiveness of metamaterials on noise reduction in low frequency range is validated.(3)Based on the model,the effect of the structure parameters on the coefficient of sound absorption of metamaterials is discussed.Through the modification of the structure parameters and the structure of the mass block,the model structure with higher performance is obtained.And experimental method on testing the effectiveness of low frequency noise reduction and sound insulation through making sample structure is provided,which can further validate the effectiveness of the model material.