Modelling of nonlinear hunting instability for a high-speed railway vehicle equipped by hollow worn wheels

Abstract

One of the reasons for frequent vibrations of coaches and hunting instability are hollow worn wheels. The main purpose of this paper is to investigate the effect of the wheel surface hollowing on the inconstancy and vibrations of a wagon. Considering the nonlinearity of the hollow surface, as well as both single and double point wheel-rail contacts are the significant points of this study. In order to do this, 800 wheel profiles of 100 coaches were measured in a controlled manner in a period of six months as an infield study. Statistical methods were used to categorize the measured hollow wheel profiles and select eight of the most observed ones. Then, a nonlinear mathematical model of a high-speed railway vehicle with 21 degrees of freedom was used for dynamic analysis of a wagon equipped by the hollow worn wheels on a tangent track. In order to model the effect of hollowing on the dynamic behaviour of the vehicle, the nonlinearity of wheel profile was taken into account. Also, both single and double point wheel-rail contacts were considered for accurate modelling of the wheel-rail interaction forces. Based on the results of the study, the tread hollowing must be considered as an independent dimensional parameter in periodic inspections. Also, it was concluded that worn wheels should be inspected regularly and re-profiled before their false flanges exceed a limit of 2 mm, in order to prevent the hunting phenomenon, and ensure being away from derailment of a passenger railway vehicle. Validation of the mathematical modelling was performed through the modelling of vehicle in ADAMS/Rail and comparing the results.