Browsing by Author "Sobolevska, Julia H."

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    Determining the Causes of Rolling Stock Derailment From the Track Using Modern Research Methods
    (Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Kuzyshyn, Andriy; Batig, Andriy V.; Sobolevska, Julia H.; Kostritsa, Sergei A.; Ursulyak, Lyudmila V.; Dovhaniuk, Stepan S.
    EN: Abstract. The analysis of cases of rolling stock derailment from the track at PJSC «Ukrzaliznytsia» over the past 5 years has been carried out and their main types are given. It is noted that the rapid development and improvement of computer technology allows the use of computer and mathematical modelling in the study of cases of rolling stock derailment from the rail track, which makes it possible to take into account a combination of factors that have the main influence on the behavior of rolling stock when moving along the track. It has been established that the first step is the construction of a mathematical model of an object using a selected type of mathematical description: algebraic, differential, integral equations, discrete mathematics, set theory, and others. And the second step is the choice of a method for solving these models. The simulation methods are given, which, depending on the programming style, are divided into: procedural-oriented, object-oriented, logical-oriented, rule-oriented, and oriented to constraints. An objectoriented programming of a freight car has been developed, which will make it possible to evaluate its main dynamic indicators, in particular, indicators of stability from derailment. This in turn will facilitate the establishment of the main causes of rolling stock derailment from the rail track.
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    Mathematical Мodeling of the Second Stage of Spring Suspension of High-Speed Rolling Stock
    (American Institute of Physics, AIP Conference Proceedings, 2023) Kuzyshyn, Andriy; Sobolevska, Julia H.; Kostritsa, Sergei A.; Batig, Andriy V.; Boiarko, Vladyslav
    ENG: The authors of the article used a thermodynamic model of an air spring with an additional reservoir to simulate the second stage of spring suspension of high-speed rolling stock. In this model, the pressure in the air spring was determined by the differential form of the ideal gas equation of state. Since the air spring is connected to an additional reservoir by means of a pipeline, the equation took into account the change in air mass due to its overflow. When determining the mass flow rate, the flow was considered turbulent, which provided for finding the appropriate Reynolds number and head losses, which consisted of three components: friction, compression and expansion losses. The law of conservation of energy was considered taking into account the heat transfer between the air spring and the environment, as well as the transfer of energy between the air spring and the auxiliary reservoir. Using a simplified mechanical model of high-speed rolling stock, the dependence of the force with which the air springs acts on the elements of the rollingstock on its deformation was obtained, and energy dissipation when changing the parameters of the connecting element was investigated. Using of the selected thermodynamic model of the air spring in the spatial model of high-speed rollingstock will further allow assessing its dynamic performance when interacting with the railway track, traffic safety indicators and choosing the optimal parameters of the rolling stock and railway track at the design stage.
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    Research of the Characteristics of an Air Spring under Cyclic Load
    (IOP Conference, 2023) Kuzyshyn, Andriy; Sobolevska, Julia H.; Kostritsa, Sergei A.; Voznyak, Oleh M.
    ENG: The dynamic stiffness, energy dissipation per cycle and the damping coefficient of the air spring of the second stage of spring suspension of high-speed rolling stock are investigated on the basis of a simplified mathematical model. The studies were carried out in the frequency range from 0 to 15 Hz. To determine the parameters of the air spring, its power characteristic was built, the area that characterizes the energy dissipation of the system per cycle. Based on the constructed characteristics, the damping coefficient and air spring stiffness during compression and expansion were determined. The influence of the frequency of the disturbing force and the diameter of the connecting element on the investigated parameters was studied. The obtained ratios of quantities would be made it possible to optimize the parameters of spring suspension of high-speed rolling stock from the point of view of ensuring admissible dynamic performance and traffic safety indicators.
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    Ways to Improve the Mathematical Model of a Freight Car for the Execution of Forensic Railway-Transport Expertises
    (IOP Publishing Ltd, United Kingdom, 2020) Batig, Andriy V.; Kuzyshyn, Andriy; Sobolevska, Julia H.; Milyanych, Andriy R.; Hrytsyshyn, Petro
    EN: According to statistics, receipts of forensic railway-transport expertises related to the derailment of freight wagons annually grows. At the same time, an analysis of the available mathematical models of freight wagons for the study of such cases showed that at present they are not sufficiently detailed to the extent that it is necessary to analyze the causes of rolling stock derailment. Therefore, taking into account the main reasons that occurrence of such railway accidents over the last five years on the railways of Ukraine, the article selects the main directions for improving the mathematical model of a freight wagon. These directions, in turn, should cover the whole plural of factors (explicit and hidden) and identify the most significant ones regarding the circumstances of the derailment rolling stock off the track, established on the basis of a computer experiment. An algorithm and a mathematical model are proposed taken into account the influence on the dynamics of the wagon of process of closing gaps in the axle-boxes and slides, and the equations of motion of the wheelset are supplemented by a guiding force, whose value is one of the main indicators of the stability of the rolling stock.