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Determining the Deformation Characteristics of Railway Ballast by Mathematical Modeling of Elastic Wave Propagation
(MDPI, 2023) Kurhan, Dmytro ; Kurhan, Mykola ; Horváth, Balázs; Fischer, Szabolcs
ENG: The article solves the problem of theoretically determining the deformable characteristics of railway ballast, considering its condition through mathematical modeling. Different tasks require mathematical models with different levels of detail of certain elements. After a certain limit, excessive detailing only worsens the quality of the model. Therefore, for many problems of the interaction between the track and the rolling stock, it is sufficient to describe the ballast as a homogeneous isotropic layer with a vertical elastic deformation. The elastic deformation of the ballast is formed by the deviation of individual elements; the ballast may have pollutants, the ballast may have places with different levels of compaction, etc. To be able to determine the general characteristics of the layer, a dynamic model of the stress–strain state of the system based on the dynamic problem of the theory of elasticity is applied. The reaction of the ballast to the dynamic load is modeled through the passage of elastic deformation waves. The given results can be applied in the models of the railway track in the other direction as initial data regarding the ballast layer.
Entropy Application for Simulation the Ballast State as a Railway Element
(Óbuda University, Budapest, Hungary, 2023) Kurhan, Dmytro
ENG: The purpose of the paper is to develop methods of entropy application for simulation of the ballast layer operation of a railway track in the tasks of predicting and controlling the service life. The author developed a method for determining the entropy of the ballast layer as an element of a railway track through calculations of the mechanical work performed by ballast as a result of the reaction to an external load. To determine the array of stresses and deformations operating in the ballast layer space, the spatial model of the stress-strained state of a railway track based was used on the elastodynamic problem. The major part of the developed method is supplemented by the technique of assessing the entropy of a system according to the deviation measuring results in its geometric position. The geometric position of a railway track was measured by a track renewal train. Files archiving to determine the randomness of data recorded in them were carried out using the LZMA algorithm. The tasks of predicting and controlling the service life of ballast have been further developed. The usage of entropy has allowed simulating the ballast degradation as a random process that depends on cyclic stresses and deformations arising in ballast from rolling stock. For the first time, the method of assessing the quality of the track surfacing through the entropy of the ballast layer is proposed. The developed mathematical tool may be used to compare the service life of ballast in various operating conditions, which allows optimizing consistency between the track design and parameters of train movements.
Methods of Assessment of Ballast Contamination on Railways of Ukraine
(Technologija, Kaunas, 2022) Andrieiev, Volodymyr S.; Tiutkin, Oleksii L.; Hubar, Oleksіy V.; Markul, Ruslan V.; Mukhina, Nataliya
ENG: Ukrainian railways use a wide variety of methods for determining ballast contamination. Some regional branches of JSC "Ukrzaliznytsia" prefer to replace the old ballast with new instead of cleaning it. Others do the cleaning of crushed stone ballast. The periodicity of such crushed stone cleaning depends on local conditions and features of cargo transportation. Ballast contamination assessment plays an important role in this matter. The essence of the research is to reduce the time for obtaining results on the assessment of ballast contamination and to simplify it for use by one or two persons, who can act as track installers.
Modeling of the Dynamic Rail Deflection using Elastic Wave Propagation
(Shahid Chamran University of Ahvaz, 2022) Kurhan, Dmytro ; Fischer, Szabolcs
ENG: There is a class of tasks that requires considering the dynamics not only for rolling stock but also for the response of the railway track. One of the directions of railway transport development, which encourages the transition to fundamentally new dynamic models of the railway track, is undoubtedly an increase in traffic speed. To solve such problems, the authors applied a model of the stressed-strained state of a railway track based on the dynamic problem of elasticity theory. The feature of this model is the calculation of dynamic stresses and deformations induced by the spread of elastic waves through the objects of the railway track. Based on the mathematical modeling of stress propagation in the under-rail basis, authors have shown the influence of various objects of a railway track on the formation of the outline of the front of the elastic wave and determined the main time intervals. Furthermore, the authors propose the following analytical method, which, in addition to the soil's physical and mechanical properties, considers the properties of the ballast as a layer that transmits pressure to the roadbed and takes an active part in the formation of the interaction space.