Investigation of wheel/rail interaction on wheel flange climb derailment and wheel/rail profile compatibility

Wheel and rail are two important elements in the rail vehicle/track system. Due to their specially designed structure and shapes, wheel and rail interaction significantly affect the lateral dynamics of a rail vehicle. The vehicle lateral dynamics is the major cause of derailments, such as vehicle lateral instability on tangent track and wheel flange climb derailment on curved track.; This work seeks to understand the mechanisms of wheel/rail interaction and apply these theories to search the practical solutions on wheel flange climb derailment and wheel/rail profile compatibility.; Based on the wheel/rail contact theory, the mechanism of wheel flange climb derailment was extensively investigated using a computer simulation model and the track test data. The parameters that affect flange climb derailment were analyzed. The study showed that wheelset angle of attack has a significant effect on wheel flange climb derailment.; New wheel flange derailment criteria have been proposed as a result of this study. The new criteria address two important aspects, single wheel L/V ratio and LV distance limit. The criteria provide considerable relief over the current criterion for the situation of small and negative wheelset angles of attack.; The current 50 milli-second L/V duration limit used in Association of American Railroads's Chapter XI standard has been evaluated. This wheel climb derailment study indicated that the wheel L/V distance limit is a much reliable criterion than a fixed time duration limit.; Wear is an unavoidable outcome of wheel and rail interaction. This work has further developed the concepts of compatible profile design to improve wheel/rail contact wear. It includes: (1) Addressing the strategy of designing a wheel profile to have good compatibility for a specified rail profile; (2) Developing a technique to expand a rail profile into a wheel profile; (3) Developing the methodology to evaluate the compatibility of wheel/rail profiles.; An example of applying above concepts and methodology to design new wheel profile and to evaluate wheel/rail profile compatibility is presented in this section. This wheel profile developed was specially designed for the Jubilee Line of London Underground Limited. The new designed wheel profile showed 50 percent lower maximum contact stress, 20 percent wear index level in one journey, and a relatively even distributed wear pattern, compared to the existing wheel profile.