Band Gap Characteristics of Vibration Isolators of Phononic Crystals under Floating Slab

In order to improve the vibration damping effect of the floating slab track and hinder the propagation of the vertical vibration energy of the floating slab to the rail base, a vibration isolator for the floating slab track based on the local resonance mechanism of phononic crystals is developed. The band gap characteristics of phononic crystals with local resonance for the isolator are studied by the finite element method, and its vibration damping effect in the band gap frequency range is verified. The vertical stiffness of the isolator is calculated, and the finite element model of the three-dimensional floating slab track with these isolators is established. The force transmissibility and the base acceleration response of the whole structure are calculated, and then compared with the results of the traditional steel spring floating slab. The results of this work show that the isolators have a band gap of phononic crystals with local resonance, which suppresses the vibration in the frequency band of 50−150 Hz. The vertical static stiffness of the isolators are similar to that of the traditional steel springs, i.e., 6.0 kN/mm. It retains the vibration isolation performance of the steel spring floating slab track in low natural frequency, and has band gap suppression characteristics in the frequency band of 50−120 Hz. The force transmissibility is reduced by about 10 dB at around 51 Hz. The base acceleration response in the 51−150 Hz is significantly smaller than that of the normal steel spring floating slab track, and the base acceleration response in the 51−60 Hz is reduced by about 30% compared to the steel spring floating slab track. Therefore, the developed isolator is able to improve the vibration damping performance of the floating slab track.