Wagon-track modelling and parametric study on rail corrugation initiation due to wheel stick-slip process on curved track
As a result of the rail corrugation formation due to the wheel stick-slip process, a nonlinear wagon-track model on curved track has been developed. In this model, wagon movements were described using up to 78 degrees of freedom (Dofs). Two wheels in a wheelset are coupled through the stiffness coefficients corresponding to the natural torsional and bending modes of wheelset. The track is considered as the discretely supported distributed-parameter track modelling with one layer. In the wheel-rail interface, before the creep saturation point sNc (s - static wheel-rail friction coefficient, Nc - normal force), the creep forces and moments are calculated using Kalker’s linear creep theory. After that point, the total wheel contact patch slides on rail, and the friction force will be kNc (k - kinetic friction coefficient). Simulations show that the frequency of wheel stick-slip process is composed of a basic frequency, which matches the sleeper-passing frequency and the combined torsional and bending frequency of the wheelset. The later appears as double or triple frequency of the basic frequency, and forms the wavelength of rail corrugation at different situations. Generally, the wheel’s stick-slip process on the high rail oscillates at the basic frequency. The dominant frequency of wheel’s stick-slip process on the low rail is double basic frequency. The effects of the wheel-rail friction characteristics, the wheel-rail profiles, the wheelset’s torsional and bending frequencies, and the curved track parameters such as curvature and cant on wheel stick-slip process have been investigated.