Comparative Analysis on Applicability of Four Wheel-Rail Vertical Contact Models for Coupling Vibration of Vehicle-Track System

To further simplify the calculation of vertical wheel-rail force, the secant linear approximation model and tangent linear approximation model were put forward based on Hertz nonlinear contact model. Meanwhile, the corresponding expressions were deduced for wheel-rail vertical contact stiffness, the induced additional stiffness matrix and additional wheel-rail force of vehicle-track system. The double-block ballastless track was taken for example and the overall dynamic equations of vehicle-track system were established. The dynamic response of vehicle-track system, the frequency spectrum of wheel-rail vibration and the applicability conditions of time step were respectively calculated and compared by Hertz nonlinear contact model, wheel-rail vertical tight contact model, secant linear approximation model and the tangent linear approximation model. Results show that Hertz nonlinear contact model can be replaced by tangent linear approximation model, regardless of whether rail irregularities are considered. Four wheel-rail vertical contact models can all be adopted for analyzing the vertical acceleration of car body. Hertz nonlinear contact model, secant linear approximation model and tangent linear approximation model can be adopted for analyzing vertical wheel-rail force, the vertical displacement of rail and the vertical acceleration of wheelset. Hertz nonlinear contact model and tangent linear approximation model can be adopted for analyzing the vertical acceleration of rail at wheel-rail contact point. The calculation results of wheel-rail vertical tight contact model in high frequency band have larger error because it assumes that wheelset and rail are never separated in vertical direction. For each band of track irregularity, the calculation errors of Hertz nonlinear contact model, secant linear approximation model and tangent linear approximation model are all in an acceptable range when the time step is less than 1 ms. © 2016, Editorial Department of China Railway Science. All right reserved.