Effect of operating conditions on the time-frequency characteristic of high-speed vehicle-turnout dynamic interaction using synchrosqueezed wavelet transform

Structural irregularities are a primary source of vibration when vehicles traverse turnouts. This study investigates their impact on the time-frequency characteristics of vehicle dynamic responses under varying operating conditions, focusing on the crossing zone of a No. 18 ballastless high-speed railway turnout. A vehicle-turnout coupled dynamic model incorporating rail flexibility is developed, and the time-frequency features of vehicle responses under different conditions are analysed. The results reveal that structural irregularities in the crossing zone lead to higher peak values and more pronounced high-frequency components (250–850 Hz) in vertical wheel/rail forces in the facing direction compared to the trailing direction. Furthermore, the vertical vibration acceleration of the point rail in the facing direction exhibits higher peak values, greater energy in dominant frequency components, and the emergence of a new dominant frequency band (70–150 Hz). Differences in vertical wheel/rail forces and point rail vertical vibration acceleration across vehicle types are primarily evident in the high-frequency range (above 150 Hz). Additionally, increasing speed amplifies dynamic response amplitudes, peak values, and vibration frequencies. This study provides critical insights into the dynamic response characteristics of turnouts under various conditions, offering a foundation for damage detection and operational assessment.