Non-Hertzian contact analysis of heavy-haul locomotive wheel/rail dynamic interactions under changeable friction conditions

Abstract

Wheel/rail dynamic interactions of heavy-haul locomotives are highly nonlinear and complicated due to large traction/braking loads, frequent anti-slip control and complex wheel/rail interface environment. The wheel/rail dynamic interactions, as well as the interface wear, have been broadly studied by means of Hertzian contact analysis, but the wheel/rail contact is essentially a non-Hertzian contact matter. This paper presents an investigation of wheel/rail dynamic interaction characteristics of a heavy-haul locomotive subjected to traction loads and dry/wet/greasy contact conditions by using a non-Hertzian contact method. For this purpose, a comprehensive dynamics model for heavy-haul train-track coupled system is established. A non-Hertzian normal contact algorithm and the corresponding creep algorithm are employed to solve wheel/rail normal and tangential contact forces, respectively. The locomotive wheel/rail dynamic interactions under different contact conditions and traction efforts are discussed. The simulation results indicate that traction effort and friction conditions have a significant influence on the contact forces, distributions of contact stress, and adhesion-slip region in the wheel/rail contact patch. The adhesion-slip distributions were found to reach full-slip under the lowest-adhesion conditions, and the wear index was found to be much greater than that under dry condition.