Railway noise reduction by periodic tuned particle impact damper with bounce and pitch-coupled vibration modes

In this study, a two-dimensional TPID (tuned particle impact damper) was proposed for reducing vibration via the interactions between the bounce and pitch vibration modes of the mass damper. To reduce the broadband vibration energy, the inelastic particle impact was utilized. The influence of the inelastic impacts on the rail vibration was investigated by the wave approach. To analyze the wave propagation characteristics, the periodic structure comprising the track and TPID was considered. The effects of the damper types, width, and loss factor on the complex wave propagation constant were investigated. The proposed TPID was applied to the actual rail. The track decay rate in the vertical direction increased by 3.2 dB/m. Accordingly, the proposed TPID effectively reduced the broadband rail vibration and allowed the tuning for optimal performance at multiple frequency ranges. With this actual installation on the track excited by the operating trains, the noise reduction performance both for moving passenger compartments and nearby residential area was verified. The sound levels in the residential area and in the passenger compartment decreased by 5.7 and 3.4 dBA, respectively. The proposed damper utilized the metallic components with advantages on rapid attachment and detachment. The proposed noise-control methodology is a cost effective vibration treatment to assure environment-friendly rail system.