An acoustic black hole absorber for rail vibration suppression: Simulation and full-scale experiment

Rail vibration suppression is important to reduce rail noise radiation and ensure vehicle ride comfort. Conventional rail absorbers have been demonstrated to be effective for suppressing rail vibration; however, their effective frequency bandwidth remains limited. Herein, for the first time, we propose a broadband rail absorber, called an acoustic black hole (ABH) absorber, for rail vibration suppression. This novel ABH absorber consists of a variable-thickness cantilever beam with a power-law profile covered by a viscoelastic damping layer. A 3D finite element model of a 12.35-m long full-scale rail with ABH absorber was developed to investigate its performance. The effects of the thickness and loss factor of the damping layer on the rail vibration-suppression performance were investigated via a parametric study. In addition, a full-scale experiment was conducted on an actual rail to investigate the vibration-suppression performance of the ABH absorber. Both numerical and experimental results indicate that the ABH absorber can significantly reduce rail vibration at tuning frequencies and provide broadband vibration suppression within the non-resonance range. The experimental results demonstrate that the ABH absorber increases the track decay rate at frequencies above 100 Hz; in addition, a maximum track decay rate of 5.85 dB/m was achieved. This study may help to develop next-generation rail absorbers, which is important for developing sustainable and eco-friendly urban rail transit.