CRITERIA FOR WHEEL FLANGE CLIMB DERAIMENT CONSIDERING WHEELSET ANGLE OF ATTACK

摘要

In order to develop wheel flange climb derailment criteria which are more suitable for transit vehicles in China, the research and analytical methods were proposed with an example of Beijing Subway B-style vehicles with an LM wheel/CHN 50 rail profile combination. The conditions necessary for quasisteady derailment of a wheel were first considered. The simple equilibrium of forces on the inclined plane of contact between wheel and rail were discussed. Kalker linear rolling contact theory was utilized to discuss the effect of wheelset angle of attack (AOA) on the lateral creep force which determined the minimum lateral-to-vertical(Q/P))force ratio combined with normal force and the maximum contact angle. The criteria were based on the simulation results obtained from computer simulation of derailment using ADAMS/Rail package. The simulation results showed that QIP force ratio decreased with increasing AOA when AOA is in a specific range. The linear characteristic between the transformed QIP force ratio and AOA was obtained through a nonlinear transformation. The method of least squares fitting was utilized to determine the functional relationships. The derailment coefficient criteria considering wheelset AOA was proposed. When wheelset AOA bigger than 0. 3°, QIP force ratio must be lower than Nadal's value; when wheelset AOA smaller than 0. 3°, QIP force ratio must be lower than 1/(0. 09AOA+0. 58) for vehicle to run safely without flange climb derailment.