Study on the Vibration-Damping Mechanism of a New Phononic Crystal Suspension Equipped on Underwater Gliders

Abstract

The vibration caused by the movement of internal actuating components within an acoustic underwater glider can interfere with onboard sensors. However, as a new vibration-damping material, phononic crystals can effectively reduce this impact. Using simulation and an underwater test, this work studied the vibration-damping mechanism of the phononic crystal suspension (PCS) designed by Tianjin University, China. The bandgaps and the modes of PCS were calculated first, which offered basic data for the following simulation. Then, the relationship between the modes and attenuation zones (AZs) were broadly considered to reveal the variation law of the AZs with the change in modes, both in the air and under water. Finally, an underwater test was carried out to verify the good vibration-damping effect of the PCS. The results show that the cutoff frequency of the AZs could be predicted by finding the relevant modes. The PCS showed a good vibration-damping effect from 170 Hz to 5000 Hz in the underwater test, with a maximum decrease of 6 dB at 2000 Hz. Finally, the damping of the PCS could suppress the overlap of modes that resulted from Bragg scattering. This work will also provide theoretical guidance for further study on the optimization of phononic crystal mechanisms for vibration damping.

Keywords

• underwater glider
• phononic crystal suspension
• vibration-damping mechanism
• vibration transmission rate
• acoustic–solid coupling