Fundamental Research Of Phononic Crystal And Application To Vibration And Noise Reduction

The various requirements of prevention and control of noise of modern societylead to the rapid development of contemporary noise control engineering technology.Choosing the proper sound insulation materials is one of the most basic and mostcommonly used technical measures in the noise control project.Periodic composite material or structure with elastic wave band gap characteristicsis called phononic crystal, the important features of phononic crystal is: the existence ofelastic wave band gaps, and the propagation of elastic wave within the scope of theband gaps in phononic crystal will have strong attenuation. Therefore, phononic crystalhas a huge potential in noise and vibration control. This paper take the noise controlpractical application of phononic crystal in low frequency as the breakthrough point, forthe Bragg scattering phononic crystal and local resonance phononic crystal, conduct acomprehensive research of causes of the forbidden band and influence factors of theforbidden band characteristics, and complete the application of phononic crystal insound insulation function through the computer finite element simulation andexperiment verification.First, we analyze the theory of phononic crystal forbidden band, calculate the bandstructure of the traditional1-D Bragg scattering phononic crystal. According to therequirements of practical application, we put forward a kind of four groups phononiccrystal structure which forbidden band frequency is far lower than that of two groupphononic crystal, and calculate the band distribution; At the same time, we also studythe mechanism of the local resonance phononic crystal with three groups band gap.The composite characteristics of phononic crystal material lead to the diversity ofthe influence factors for the band gap, so it is necessary to study the influence factors ofthe band gap, through the analysis of the various influence parameters on the band gapsmake a judgment about the feasibility of phononic crystal within the scope of the lowfrequency sound insulation application, for the next step, the analysis provides theorybasis for the choice of parameters in the simulation calculation and experimentalverification.In order to validate the feasibility of the application of phononic crystal, accordingto the results of theoretical analysis we determine each parameters of the phononiccrystal, and establish a finite element model of phononic crystal and boundary elementmodel for acoustic analysis, using the acoustic boundary element module in Virtual LabAcoustic for the simulation of sound insulation properties of phononic crystal.At last, we prepare three samples of local resonance phononic crystal and build the sound insulation testing platform, then carry the phononic crystal acoustic insertion lossexperiments to verify its sound insulation ability. Then we analyze the experimentalresults, and summarize the law of the sound insulation performance of phononic crystal.