Assessment of the influence of wheel and rail wear on flange climbing derailment using derailment criteria

Wheel flange climbing is a type of derailment that occurs when the flange side of the wheel gradually climbs onto the rail head. One factor influencing this phenomenon is wheel and rail wear. Existing assessment methods either fail to account for the critical derailment limits or rely on conservative criteria such as Nadal's and Weinstock's. Hence, this study comprehensively investigates the influence of wheel and rail wear on both derailment coefficients and critical derailment limits when a rail vehicle negotiates a curved track. Multibody vehicle dynamics simulations were conducted to numerically determine the highest derailment coefficients for various combinations of a set of nominal and worn S1002 wheel and UIC60E1 rail profiles. In addition to traditional criteria, a 3-D complete single-wheel and complete wheelset derailment criteria were applied to calculate the critical derailment limits. Results indicate that the curve radius, wear-induced changes in contact angles, contact location, number of contact points and distribution of contact forces influence the derailment coefficients and critical derailment limits. Compared to the complete single wheel and wheelset criteria, Nadal's and Weinstock's limits overestimate the derailment risk index of wheel flange climbing derailment due to wheel and rail wear by up to 70% and 40%, respectively.