Research On Aircraft Structure Vibration And Noise Reduction Based On Phononic Crystal Characteristics

In the past twenty years,the concept of phononic crystal has emerged,which makes people have a new point in the research field of acoustic functional structure and acoustic components.Especially,after the appearance of local resonant phononic crystals,it is more feasible to apply the band gap characteristics and sound insulation and vibration isolation characteristics of phononic crystals in practical engineering.The band gap characteristic means that the elastic wave in a certain frequency range cannot pass through the phononic crystal.By studying the band gap characteristics in the low frequency range,we can deal with the impact of aircraft vibration and noise which is mainly low frequency noise.In this paper,we first deal with the numerical examples and experimental results in the literature.By using plane wave expansion method,time domain response method and finite element method,the energy band structure diagram,frequency response curve and sound insulation loss curve are obtained.The correctness of the research method is verified.In order to research the sound insulation and vibration reduction effect of phononic crystal structure,it is necessary to study the band gap characteristics of phononic crystal cell first.In this paper,a three component local resonance phononic crystal cell model is established.From the point of view of physical and geometric parameters,the parameters which have great influence on the low frequency band gap are obtained,including scatterer density,filling rate,core shape and so on.According to the above conclusion,Choosing suitable materials to construct phononic crystal cell.The model of phononic crystal plate is established after the cells are arranged periodically.From the vibration isolation and sound insulation characteristics,the vibration and noise reduction effect of the phononic crystal plate is calculated,and the vibration and noise reduction characteristics of the phononic crystal plate are optimized.The results show that the core combined phononic crystal plate can optimize the frequency response and increase the effect of vibration isolation and noise reduction.The sound insulation of the phononic crystal plate at different incident angles is calculated,and the influence of the incident angle on the sound insulation effect is obtained.The vibration and noise reduction effects of rod,plate,beam and other structural forms of phononic crystals in aircraft structural system are calculated.The results show that the vibration isolation effect of the bending vibration can be optimized by using the three component form for the phononic crystal beam,and the noise in the band gap of the aircraft structure can be effectively reduced by using the phononic crystal.