A new criterion for assessment of train derailment risk

Abstract

A new criterion for prediction of train derailment is presented in this article. A three-degrees-of-freedom (3 DOF) wheelset model is used to identify the main dynamic parameters that affect wheelset derailment. Using these parameters and conventional definition of derailment coefficient, a new criterion for prediction of wheelset derailment is introduced. The proposed criterion, in addition to providing the required precision in prediction of wheel set derailment, requires measurements that are easy to perform. To evaluate the capability of the new criterion in prediction of derailment, a full wagon model with 48 DOF moving on a track with different random irregularities was used. The track is assumed to be mounted on a viscoelastic foundation. The wagon model is a three-dimensional, non-linear model of a train passenger car. The model includes non-linear elements for primary and secondary suspension systems. Friction and slack between elements, the centre pivot with kinematics constraints, forces between pads, and bolster are also included in this model. The motion of the wagon on tangent and curved tracks is simulated for different travel speeds. Derailment coefficient and a new derailment criterion are used to investigate the possibility of wheelset derailment in each case. The study shows that the new criterion can very well predict wheelset derailment and can duplicate the predictions by conventional derailment coefficient ( Y/ Q).