Analysis of rail corrugation in cornering

Rail corrugation in cornering is examined via a non-linear time-domain model of a bogie cornering. The model is computationally fast due to a modal description of a wheelset that includes bending and twisting modes of its axle as well as flexing of wheel hubs. The modal wheelset model is tuned to match finite element predictions of its natural frequencies. The rails are also modelled using modal parameters found by fitting field measured receptance data. The model predicts corrugation over a range of wavelengths from one wavelength per sleeper to shorter wavelengths below 100 mm. It is found that a range of wavelengths around 100 mm, can be excited on a curve of 300 m radius, in addition to longer wavelengths associated more with track or primary suspension dynamics. The mix of frequencies present changes as corrugation grows, the wavelengths around 100 mm dominating at later times. Stick-slip between wheel and rail is evident, especially on the leading axle, and contributes to both long and shorter wavelength corrugation. The shorter wavelengths relate to a peak lateral response of the track, and a minimum vertical response. The sliding oscillation causing wear is mainly a stick-slip oscillation of lateral creep. Parametric excitation from crossing sleepers is represented by changing the track parameters. It is shown that sleeper crossing excitation can have an important influence on the extent of stick-slip oscillation, especially with stiff railpads on concrete sleepers, and a coefficient of friction that decreases with increased sliding.