One-dimensional binary phononic band gap shaft structure for reducing torsional vibration

Torsional vibration is one of the common phenomena in rotor shafts, which can reduce the service life of the shaft and influence the reliable operation of the machine. In this paper, a one-dimensional binary phononic-band-gap structure based on the local resonant effect is presented and the propagation of torsional waves in the shaft is studied theoretically and numerically. In the structure, based on the phononic band gap (PBG) mechanisms, soft rubber rings are distributed periodically around the shaft without much changing the dynamic shaft parameters. The structure can suppress the torsional vibration within the band gap. The method of combined the transfer matrix method and the lumped-mass method are used to study the torsional vibration band gap of the PBG-like shaft theoretically, and the finite element method is employed to calculate the vibration attenuation spectra of a finite sample of it stimulatingly, showing that the range of the band gap can reach 600Hz with the average attenuation of the vibration amplitude about 60dB. Moreover, the effect of the structure damping on the center frequency and the vibration attenuation in the band gap is investigated. The results of the theoretical and numerical studies show that the one-dimensional phononic crystals with Binary Structures presented can reduce the torsional vibration in the band gap efficiently, and thus can also inhibit the undesirable vibration transmission and sound radiation. The low frequency torsional gap in the PBG-like shafts would provide a potential application in torsional vibration control.