Wheel-Rail impact and vibration characteristic frequencies at High-Speed railway turnouts

The wheel load transition in railway turnouts leads to significant wheel -rail impacts, particularly in high-speed crossings. Compared with the plain track, the variable rail profiles, multi -point wheel -rail contact, and structural flexibility of turnouts make it difficult to accurately estimate the high -frequency wheel -rail impacts and identify the characteristic frequency mechanism of dynamic interaction during wheel load transitions. To address these challenges, extensions are made to vehicle -turnout coupled dynamics in time domains and wheel -rail interaction models in frequency domains. The modal superposition -based time domain model considers the flexibilities of the systematic turnout structure and rotating wheelset, expanding the valid frequency range up to 2 kHz. Simulated modal properties of turnout rails align with the field -measured frequency response function (FRF) and operating deflection shape (ODS). For the frequency domain model, a mathematical expression for turnout structural irregularity is introduced as roughness excitation. Eigenfrequencies of the wheel -turnout coupled system and characteristic frequencies of wheel -rail interaction are derived from validated mobilities of turnout rails and wheelsets. Simulations are conducted when a vehicle passes turnouts at speeds of 250 - 400 km/h. The simulated vertical wheel -rail force in time domain models is comparable to the field track inspection train data. At a speed of 350 km/h, the vertical wheel -rail force converges at the cut-off frequency of 1500 Hz, and its characteristic frequencies are close to eigenfrequencies of the wheel -rail system. However, the turnout dynamic model does not account for contact nonlinearities between the long point rail and baseplates, leading to smaller simulated FRF amplitude for the long point rail and slightly higher wheel -rail forces calculated by the frequency domain model in 200 - 400 Hz. Nevertheless, the vertical wheel -rail force and rail acceleration predicted by the frequency domain model align well with results from time domain integrations.