Вестник Научно-исследовательского института железнодорожного транспорта (Jan 2024)
Numerical modelling of train pulling off with incomplete brake release
Abstract
Introduction. Unsteady train movement causes abrupt changes in the traction magnitude with oscillating and sometimes shocking relative movements of the cars. Under these conditions, the automatic couplers are subjected to stress, which leads to their breakage. The research is intended to determine the magnitudes and nature of changes in longitudinal dynamic inter-car forces arising when the train pulls off and pulls off without holding the time of full brake release (with braking forces acting in the tail section).Materials and methods. Calculation of the longitudinal forces occurring when the train pulls off applies numerical modelling. The digital multi-mass model of each train is a system of solid bodies connected by elastic ductile bonds. The author developed a simplified model of the automatic coupler that takes into account the stiffness and ductility of the draft gear as well as the clearances in the shock and traction devices.Results. The researcher performed numerical experiments of the three operation modes: train pulling off; train pulling off without holding the time of full brake release of the last car (with the last car assumed stationary); train pulling off without full brake release in the last third of the train under variable braking forces. Modelling for each type of virtual experiment established the nature and magnitude of changes in the longitudinal inter-car forces: in the steady-state motion and in the transient, the most loaded mode of train operation.Discussion and conclusion. The trains under consideration show that the maximum inter-car loading when pulling off with the last car stationary is, on average, twice as high as the maximum inter-car loading when a train pulls off after full brake release. The author determined that incomplete brake release in the last third of the train under selected conditions increases the maximum longitudinal loading by 2.22–6.23%.
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