Investigation of the nonlinear characteristics of wheel/rail vibration system

Field measurements showed that wheel vibrations generated on curved tracks are still significantly stochastic, even with the same route. This phenomenon is one of the typical characteristics of nonlinear systems. To analyze the reason for the nonlinearity of the wheel/rail system, a three-degree-of-freedom wheel/rail coupled dynamics model is developed. The simulation results reveal nonlinear characteristics in the wheel/rail system, including sum frequency, difference frequency, and double frequency. To investigate the inherent nonlinearities in wheel/rail interactions, the relation of longitudinal creepage-dependent longitudinal friction coefficient is analyzed, and the results show that the creepage-dependent longitudinal friction coefficient is nonlinear with longitudinal creepage, which may lead to the nonlinearity of the wheel/rail vibration system. In comparison, the torsional vibration is analyzed when the longitudinal friction coefficient remains constant. The results show no nonlinear characteristics, indicating that the nonlinear behavior of the wheel/rail system arises from its inherent nonlinear friction creepage characteristics.