A FINITE-ELEMENT MODEL OF RAILWAY TRACK AND ITS APPLICATION TO THE WHEEL FLAT PROBLEM

To study the dynamic interactions between the railway vehicle and trac k, a finite element model of infinitely long track is developed. The t rack is represented by a Timoshenko beam an discrete pad-tie-ballast s upports. The non-linear factors such as loss of wheel-rail contact, ra il lift-off from the tie and tie lift-off-from the ballast are taken i nto account. A multi-point wheel-rail contact model is also proposed. The dynamic forces on the track and the strains on the rail are direct ly calculated from the model. The vehicle could travel on the track fo rever with an arbitrary time-dependent speed. The steady-state respons e of a vehicle-track system for a perfect wheel carrying a constant lo ad and travelling at a constant speed over a track with no irregularit ies is studied using the finite element model and is presented. The im pact loads due to wheel flats are also studied with this model. The re sults show a good correlation with the experimental data available in the literature. Influences of system parameters on the impact loads du e to a wheel flat are also investigated. The results show that the axl e load and vehicle speed are the important factors affecting the wheel -rail impact loads. The impact forces transferred from the rail to the tie are strongly affected by the pad stiffness and tie mass.