Thesis for a candidate of technical sciences degree in specialty 05.22.20 "Operation and repair of transportmeans" – Dnipro National University of Railway Transport named after Academician V. Lazaryan, Dnipro, 2021.
The work was performed at the Department of Applied Mathematics of the Dnipro National University of Railway Transport named after Academician V. Lazaryan of the Ministry of Education and Science of Ukraine.
The thesis is devoted to solving the problem of improving the existing system of maintenance of technical objects of railway transport, namely, to take into account the influence of dependent equipment failures.
The introduction substantiates the relevance of the topic of the dissertation, formulates the purpose and main tasks of the research, determines the scientific novelty of the work and the practical significance of the results obtained, shows the connection of work with scientific themes. Information is given about the testing of the results of work, the personal contribution of the author and his publication.
In the first section of the thesis, an analysis of the current state of traction rolling stock hold systems was carried out. Their advantages and disadvantages are determined. The lack to take into account the consequences of dependent failures of the main components of locomotives in any existing system of maintenance of technical objects of railway transport was detected. The analysis of transport events in the locomotive economy was carried out, which revealed that most of the accidents arose precisely due to the reasons for the equipment failures.
According to the results of the first section the expediency of taking into account the dependent failures of elements of technical systems during construction of a rational system of holding these objects has been proved.
The main task of rail transport is to ensure the needs of the population in transportation, that is, the solution of problems and the national economy and social needs. Modern realities also demand a careful attitude towards the use of ecological resources (water, fuel, etc.). Therefore, the question arises about the choice of rationality criterion when improving the railway transport technical objects maintenance systems.
In the second section of the thesis, a systematic analysis of the theoretical foundations for improving the locomotive retention system was carried out. The main quantitative characteristics of the reliability of the system and the concept of dependent failure are considered. Modeling of failure to work and recovery process was performed. A recurrence ratio is described that describes the distribution of dependent failures on the system. Based on this correlation, the deterministic and probabilistic models of the distribution of dependent failures on the system are developed. This allowed taking into account the costs of eliminating the consequences of dependent failures in the maintenance system of technical objects.
To assess the quality of the maintenance system and other aspects of the work of the locomotive park, a method is proposed based on methods of reducing the dimension of the data. With this technique, it is possible to analyze the state of the locomotive economy on various aspects (in terms of traffic safety, in terms of the quality of the implementation of the system of locomotive hold, in terms of operational safety, etc.).
The third section of the thesis a method for determining a rational maintenance system using the mathematical apparatus of vector optimization. As criteria of rationality, according to the results of the analysis in the second section, the following indicators are selected: costs of expenses, time expenditures, expenses of ecological resources. The problem of vector optimization for three functions, which are described in detail, is formed. The basic conditions for existence of the solution of this problem are formulated.
In the fourth section of the thesis, an estimation of the work of the locomotive park was carried out by methods of reducing the dimension of data, which made it possible to get rid of redundant duplicate information from a large number of output indicators of the activity of the locomotive economy.
In order to evaluate the efficiency of the maintenance system, using the method of the main components and the hierarchy analysis method, a single integral index, the Index of execution the maintenance system, was developed.
The fifth section of the thesis presents the methodology and calculates the cost of the life cycle of the locomotive, taking into account the dependent failures of its equipment. This technique has allowed to determine the average cost of unplanned repair, which in turn allows you to improve the retention system. Approbation of the methodology work is carried outon data on the failure of the main equipment of electric locomotives DE1.
