Study On The Forbidden Band Properties Of One-dimensional Solid And Solid Periodic Phononic Crystals Thin Plate

Phononic crystals are periodic acoustic function composites with elastic waves band gap characteristic. The essence characteristic of phononic crystal is the phononic band gap, which make it possible to realize the control of elastic wave, and have a broad application propect in vibration and noise reduction, the design of new sensor and sound filter function sound device fabrication etc. The phononic crystal band gap characteristics used in the design of composite plate structures, not only meet the needs of practical application and acoustic coupling, have become a hot research issue in engineering field in recent years.The composite characteristics of phononic crystal material determines its band gap is affected by many factors, the feasibility of the unfluences of the parameters on the band gap to determine the application of phononic crystals in the range of low frequency vibration and sound insulation, which can provide a theoretical basis for the phononic crystal parameters experiment and practical application of the selection. So it is necessary to calculate and analyze the influence factors of the band gap comprehensively. As composite materials and natural materials are mostly solid, so this thesis studies one-dimensional solid and solid perodic phononic crystal thin plate band gap characteristics, calculation and analysis of the influence of composition ratio, elastic modulus and other main factors on the band gap properties by lump-mass method and finite element method.Firstly, the studies on the forbidden band characteristics of one-dimensional solid and solid periodic phononic crystals by lumped-mass method. The main influencing factors of the the first band gap of initial frequency and band width is discussed, compreses the elastic modulus of component material, composition ratio, cell thickness, material density ratio. The results show that: the phononic crystal component ratio in certain material combination can affect the band gap of the initial frequency and band width when the other parameters are determined, and ratio of component to a certain value, the lowest initial frequency and the largest width of the band gaps. Only the material density difference is very small, the first band gap of initial frequency and band width will be affected. In theory, imporve the cell thickness can effectively reduced the phononic crystal first band gap of initial frequency and band width, but in practical application, the thicker of the cell thickness will lead to greater phononic crystal quanlity so as to make the application more difficult. The small change of elastic modulus to the first band gap of initial frequency and band width by the greater impact, therefore, by increasing the elastic modulus of component materials is helpful to get lower initial frequency of band gap.Secondly, based on the finite element method, one-dimensional solid and solid periodic phononic crystals thin plate model is established by finite element software Comsol Multiphysics, calculation and analysis of the material composition ratio and structure ordered pairs of phononic crystal thin plate band gap, and influence of composition ratio of one-dimensional three element periodic phononic crystals band gap characteristics of thin plate is also calculated, The results show that: one-dimensional solid and solid periodic phononic crystals thin plate with the increase of the bulk material in the direction of the length of the cycle, the band gap broadening and moves to low frequency, with the decrease of the ordered structure, the band gap also brodening, the band gap of initial frequency decreased. Therefore, to obtain the ideal phononic crystals thin plate with low band gap of initial frequency and large band width, the material componet ratio should be small, namely scatterer material component should be large.Finally, the band gap characteristics of one-dimensional solid and solid periodic phononic crystals thin plate which matrix and scattering selected for different material combinations was calculated, analysis of the material combination optimization to build one-dimensional solid and solid periodic phononic crystal thin plate are: material density of scatterers to be large, the material parameters to be small difference.The research enriches the study of phononic crystals thin plate forbidden band theory, provides a reliable basis for the application of phononic crystals plate structure, the results have important reference value in the practical engineering application of phononic crystals on the vibration and noise reduction.