Effect of braking operation on wheel–rail dynamic interaction of wagons in sharp curve

Abstract

A heavy-haul train–track coupled dynamic model is developed based on the vehicle–track coupled theory. The numerical model is verified in two typical cases. For the calculation, the different lines are considered, which are composed by the plane curve with 400 m radius and the vertical convex (concave) curves with the 8‰ grade difference. Taking the freight wagons in the 10,000 t and 20,000 t trains as the research objects, their curing performances, the corresponding coupler behaviors, and rail displacements in the emergency and full service braking conditions are analyzed and compared. The results indicate that the alignment of horizontal curve section will cause a distinct tilt angle of wagon coupler, and the tilt amplitudes are almost unchanged for different coupler compression forces. It can be attributed to the stronger coupler stabilizing ability of the freight wagon system. However, under the influence of coupler angle, the coupler longitudinal force produces a large lateral component, which significantly deteriorates the curving performances of wagons bearing the maximum coupler compression forces. Generally, when the 10,000 t and 20,000 t trains brake in the sharp curve, the maximum values of wheelset lateral force and rail lateral displacement increase by 33% and 28%, respectively, with respect to the results calculated in the idle condition. For the dynamics evaluation of freight wagons, the train marshalling modes, the idle condition, and braking condition should be considered comprehensively according to the actual situations.