Browsing by Author "Ursulyak, Liudmyla V."
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Item The Influence of the «Train-Track» System Parameters on the Maximum Longitudinal Forces' Level(Silesian University of Technology, Katowice, Poland, 2019) Pshinko, Oleksandr M.; Ursulyak, Liudmyla V.; Kostrytsia, Serhii A.; Fedorov, Yevhen F.; Shvets, Anzhela O.EN: The main objective of the simulation is to study the effect caused by the parameters of the longitudinal profile on the maxima of longitudinal forces in freight trains of increased length during adjustment braking and running-out. To decrease the number of numerical experiments, some empirical formulae for estimating the maximum longitudinal forces during the motion of freight trains along the track with various configurations of its longitudinal profile's gradient changes have been obtained for the first time. Comparison of those forces with the permitted values, from the point of view of the railway stock strength and eventual vehicle derailment, has been performed. As a result of numerical integration of the system of non-linear differential equations of train motion for the considered driving modes, the values of the greatest longitudinal shock and quasi-static forces, as well as the dependence of the latter on the train length, initial braking velocity, on the algebraic difference of gradients and the length of the horizontal area that separates two gradients with opposite signs are estimated. The proposed mathematical model and methodology can be applied during standardization of the longitudinal profile's parameters from the point of view of the freight traffic safety for the trains of various length.Item Simulation of Braking Processes in Freight Trains(KTU leidykla „Technologija“, Kaunas, Lithuania, 2022) Ursulyak, Liudmyla V.; Zheleznov, Konstantine I.ENG: The article presents the results of theoretical research of the processes occurring in the brake cylinders of freight wagons in trains of different lengths. A detailed analysis of the real time dependences of the forces of pressing the brake pads on the wheel for various braking methods (adjustment, full service and emergency braking), which were obtained during experiments with freight trains of different lengths, was carried out. Based on the analysis performed, approximating expressions for brake pad pressure diagrams on the wheel are proposed, which can be used to estimate the longitudinal dynamics of trains using mathematical modeling in real or accelerated time. The above dependencies are especially relevant when a train is controlled using a special onboard computer system. In this case, it is necessary to quickly estimate to what results, from the point of view of traffic safety and achievement of the control goal, the implemented control modes will lead to.Item To the Problem of Train Running Safety(IOP Publishing Ltd., 2020) Pshinko, Oleksandr M.; Ursulyak, Liudmyla V.; Zhelieznov, Konstiantyn I.; Shvets, Anzhela O.EN: The paper is presenting the procedure used for establishing the cause of the wagon derailment. To do this, the computer simulations and the computational software, developed in the Dnipro National University of Railway Transport (DIIT) were used. The level of longitudinal forces and the wagons dynamic performance have been evaluated using the mathematical models of longitudinal oscillations of a train and the spatial vibrations of wagons, in particular of tank wagons. As a result of modeling we obtained oscillograms of longitudinal forces in each inter-wagon connection, the dependence of the largest longitudinal forces on travel time and distance traveled, the distribution of the maximum longitudinal forces along the train length, the speed dependence on travel time and track coordinates. We also obtained the dynamic performance of wagons: the vertical dynamics coefficients of the axlebox and central suspension, the horizontal dynamics coefficients and the derailment stability coefficient. The influence of the movable load in the tank wagons and the characteristics of rail irregularities on the stability coefficient against wheel climbing onto the rail is also considered. The presented methodology was used to determine the cause of the tank wagon derailment in a non-homogenous freight train consisting of 50 wagon tanks on an existing track section of the Lithuanian railways. When simulating the train movement, it was assumed that the train was equipped with elastic-friction absorbing devices and air distributors, turned on to the average operation mode. As a result of numerical experiments, an assumption was made about the cause of the train derailment.