Flexible moving track model for curve negotiation analysis of railroad vehicles with rail roll deflection

Abstract

In this investigation, a flexible track model based on the moving track approach is generalized for use in the curve negotiation analysis of multibody railroad vehicles. The track model consists of discrete rail and sleeper bodies defined underneath the wheelset, and the equations of motion are formulated along the track and rail trajectories using the general track geometry description utilized in the railroad vehicle dynamics simulation. In the vehicle curve negotiation, the outer rail is subjected to the overturning moment caused by the flange contact force, thus the rail roll deflection and its effect on the location of contact point need to be carefully considered for an accurate prediction of the wheel/rail contact forces for the flexible track model. To this end, the multi-variable look-up tables that account for the change in roll angles of both rails are introduced in this study. The multiple look-up contact tables are prepared for various assumed rail roll angles by the contact geometry analysis prior to the dynamic analysis, and then they are interpolated as a function of roll angles of both rails, the modified wheel lateral displacement that accounts for the rail lateral displacement, and the angle of attack of the wheelset. By doing so, existing railroad vehicle dynamics simulation algorithms assuming rigid rails can be extended to account for the track flexibility without significant modifications of the code.