The low-frequency bandgap characteristics of phononic crystal isolators with multi-hole

Abstract

A vibration isolator for a floating slab track, based on a locally resonant phononic crystal, has been designed to suppress vibrations caused by the wheel-rail interaction. In this isolator, a circular vibrator is connected to a connector through a rubber layer uniformly embedded in holes. The finite element method is utilized to compute the energy band structure and transmission loss of the vibration isolator, while the mechanism of bandgap is elucidated through the analysis of modes. The static stiffness and dynamic stiffness of the vibration isolator are calculated, which proves that the vibration isolator meets the requirements of engineering applications. The influence of the number of circular holes and the geometric parameters of the vibration isolator on the bandgap is examined. It is discovered that augmenting the number of holes and the hole diameter in the rubber layer leads to a decreased bandgap. A low-frequency locally resonant bandgap of 38.2–97.1 Hz and a relative bandgap bandwidth of 86.9 % are obtained by optimizing the vibration isolator. The vibration isolation performance of a floating slab track equipped with vibration isolators is analyzed and more robust vibration attenuation performance is obtained in the bandgap. The multi-hole phononic crystal vibration isolator is employed in floating slab tracks for rail transportation, effectively mitigating vibrations transmitted to tunnels, thus further minimizing the effects on the surrounding environment.