Abstract: The problem on out-of-round railway wheels in their service is analyzed and the wheel out-of roundness is made into categories. A new mathematical model is put forward numerically to simulate the wheel ovalization, which is called the second order periodic non-roundness of wheel. In the numerical simulation, the dynamic model of a half railway vehicle coupled with a tangent track is employed, in which elliptical railway wheels are considered in the calculation of the wheels and the rails in rolling contact. Using the new numerical method investigates the effect of the wheel ovalization on the dynamic behavior of the wheelsets in the lateral direction, and determines the critical range of wheel ovalization at vehicle speed of 200 km/h. The numerical results show that the ovalization of high speed railway wheels has a great influence on the occurring of the vehicle hunting and the lateral stability. The situation of the wheelset hunting caused by the wheel ovalization depends greatly on the combinations of the wheel ovalization extent, the vehicle speed, and the phase angle of the ovalization of the two side wheels of the wheelset. Increasing the wheel ovalization will cause a decrease in its lateral stability.

Key words: High speed train, Hunting, Lateral stability, Vehicle/track coupling dynamics, Wheel ovalization, Wheelset