Study On The Low-frequency Band Gap Characteristics Of Periodic Barrel-type Resonators In Phononic Crystal Plates

It is difficult for researchers to suppress the vibration of vertical direction to the plate direction in the academic field,when the frequency is lower than 250 Hz.The local resonance phononic crystal can suppress the vibration in the band gap,which makes it a hot spot for scholars.Based on the in-depth study of the band gap generation mechanism of local resonance phononic crystals,this paper proposes a new type of local barrel-type resonance phononic crystal plate structure,and deeply studies its local resonance mode,band gap generation mechanism and parameters.The band gap range of the bending wave is optimized to 47 Hz to 137 Hz,and has a wider band gap in the low frequency range.The main work and research results of the thesis are as follows:Firstly,a new barrel-type local resonance phononic crystal plate structure is proposed.By separating the local resonance unit movement from the thin plate and not modifying the thin plate,it is only necessary to periodically attach the resonance unit to one side of the thin plate.It can have a wider band gap in the low frequency band.A variety of excellent features make the barrel-type local resonance phononic crystal plate very useful in low-frequency vibration reduction.Then,the local resonance mode and band gap generation mechanism of the barreltype phononic crystal plate are studied in depth.The local resonance modes of typical barrel-type phononic crystal plates mainly include vertical and plate direction motion modes,horizontal direction motion modes,and torsional motion modes.The initial frequency of the band gap of the bending wave is mainly determined by the natural frequency of the local resonance motion dominated by the Z direction.The important influence factor of the cutoff frequency of the band gap is the coupling strength between the motion of the thin plate and the local resonance.The stronger the coupling strength is,The higher the cutoff frequency of the band gap,the wider the band gap width.The band gap range of a typical barrel-type local resonance unit phononic crystal plate is 58.6 Hz to 108.1 Hz,and the normalized band gap width is 0.5938812.Then the influence of the parameters of the barrel phononic crystal plate on the band gap of the bending wave is studied.When studying the influence of parameters on the band gap,the influences of the parameters on the band gap width and the normalized band gap width are summarized.The influence of the applied parameters on the band gap is used.In this paper,the band of the typical barrel phononic crystal plate is used.The gap width is increased by 80% and the normalized bandgap width is increased to 0.97826.Finally,the transmission characteristics of barrel-type phononic crystal plates under finite periodic structure are studied.The transmission characteristics of a typical barreltype phononic crystal under a finite-period structure are mainly studied and analyzed,and the vibration attenuation is below-20 dB as an index.When the size is 6x6,the band gap width and the normalized band gap width of the typical barrel type are optimal,which is enough to reflect the vibration damping effect in engineering.By splicing the 6×6 barreltype phononic crystal plates with different parameters,the transmission characteristics of the barrel-type phononic crystal plate can be optimized,and the band gap width after splicing is the union of the band gap range before splicing.In the project,the phononic crystal plate can be optimized by this idea.