Analysis of the influence mechanism of track irregularities on the coupled wideband vibration of train-track-bridge systems

The present study investigates the influence of high-speed railway track irregularities on the wideband vibration characteristics of the vehicle-track-bridge system. The elastic pad of the WJ-8B fastening system for high-speed rail was selected as the research subject for this investigation. The frequency-dependent characteristics of the elastic pad were characterised through the implementation of fixed-frequency variable-temperature testing, utilising the higher-order fractional derivative FVMP model and the temperature-frequency equivalence principle. The FVMP model was subsequently integrated into the established vehicle-track-bridge coupled dynamic model to analyse wideband vibration responses under different track irregularity conditions. The results indicate that within the coupled vehicle-track-bridge vibration system, variations in track irregularity amplitude exert a greater influence on vehicle body vibration than on track structure and bridge components. Shorter wavelength of track irregularity leads to more pronounced changes in the high-frequency vibration response of track structures and bridges, primarily concentrated within the 50–2000 Hz frequency band. This study elucidates the relationship between irregularity excitation and wideband vibration response, clarifying the vibration response of the vehicle-track-bridge system under different irregularity conditions. It provides a theoretical basis for establishing precise wideband vibration prediction models in subsequent research.