Enhanced low-frequency vibration isolation via innovative double-resonator phononic crystals

Ground vibrations induced by underground metro systems can adversely affect the surrounding environment, particularly in the context of low-frequency vibrations. Despite the introduction of various mitigation techniques, such as floating slab track (FST) over steel springs or phononic crystal vibration barriers, their efficacy in attenuating low-frequency vibrations is limited. Therefore, the main objective of this study is to develop a novel Double-Resonator Phononic Crystal (DRPC) vibration isolator. The Finite Element Method (FEM) is utilized to analyze the locally resonant bandgap characteristics, and the isolator's shielding efficacy has been assessed through the transmission spectrum (TS). Furthermore, a detailed parametric study investigates the influence of Young modulus (MOE), density, geometric dimensions, and the damping (ƞ) of different components on the TS and bandgap properties of the DRPC. This study also investigates the impact of damping by analyzing the distribution of energy and velocity within the DRPC. The findings indicate that the DRPC vibration isolator substantially develops a low-frequency bandgap (36 Hz to 151 Hz) alongside a TS closely corresponding with the bandgap, thereby verifying the model's accuracy. Moreover, among all rubber components, the damping in the middle rubber mainly governs the vibration attenuation efficiency and the bandgap properties of the isolator.