Investigation on vibration reduction performance of spiral acoustic black hole for ring-stiffened cylindrical shell

Objective This paper seeks to investigate the vibration reduction characteristics of a spiral acoustic black hole (SABH) on a ring-stiffened cylindrical shell and provide a new technical approach for the vibration reduction design of ring-stiffened cylindrical shells.

Method First, a finite element computational model of a ring-stiffened cylindrical shell with an SABH arrangement is constructed, and its structural natural frequency and vibration response characteristics are calculated and analyzed. The influence of the SABH arrangement position, helix length, and number on the vibration suppression of the ring-stiffened cylindrical shell is also investigated.

Results The results show that with a single SABH arranged on the web, the resonance peak of each mean-square velocity （MQV） of the web is significantly reduced, with the first-order resonance peak reduced by 6 dB or more, the other resonance peaks reduced by 13 dB or more, and the peak value of each MQV of the shell reduced by 8 dB or more. Increasing the helix length and number of SABHs can further improve the vibration reduction effect.

Conclusion SABHs have a minimal effect on the natural frequency of ring-stiffened cylindrical shells and deliver excellent low-frequency broadband vibration reduction performance.