Перегляд за Автор "Hetman, M.V."

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  • Ескіз
    Документ
    Analysis of tribological aspects during operation and repair of internal combustion engine valve mechanism parts
    (Хмельницький національний університет, 2024) Vychavka, A.A.; Dykha, O.V.; Hetman, M.V.
    The problem of researching mechanisms of wear of valve mechanism parts remains very relevant due to the need for constant improvement of the design and increase in durability of internal combustion engines. The paper provides an overview of modern research on the following issues: analysis of operating conditions and malfunctions of the valve mechanism of the internal combustion engine, research on friction and wear of valve mechanism parts, repair and restoration technologies, increasing the wear resistance of engine valves, modeling, calculations of valve mechanism parts. It is shown that an important aspect for the analysis of the wear resistance of valve mechanism parts is the operating conditions and the nature of damage to the surfaces of the friction pair parts. The existing hypotheses about the mechanisms of friction, lubrication and wear of valve mechanism parts are considered, the designs of test stands are given, and the results of tribological tests are analyzed. It is substantiated that the technological methods of surface engineering are becoming an increasingly viable alternative to structural changes to improve the performance of valve mechanism parts. An overview of calculation methods for assessing the stress and thermal state of valve mechanism parts of internal combustion engines is provided.
  • Ескіз
    Документ
    Experimental and analytical study of acid number variation in engine oils under operational contamination
    (Хмельницький національний університет, 2026) Dykha, M.O.; Hetman, M.V.; Dytyniuk, V.O.; Makovkin, O.M.
    This paper presents an experimental and analytical study of the variation of the total acid number (TAN) in engine oils under operational contamination. The research is aimed at assessing the correlation between the acidity growth of lubricants and their wear behavior in the four-ball test configuration. Theoretical modeling and experimental testing were performed to identify the parameters of a wear law that incorporates contact pressure, oil viscosity, hardness, and TAN as key variables. The obtained results confirm that the acid number increases significantly during oil operation: from 0.9 to 2.9 mg KOH/g—which leads to an intensified wear rate of the contact surfaces. The proposed model quantitatively describes the relationship between the acidity level and wear intensity and enables prediction of oil performance based on its physicochemical degradation. The developed approach allows for improved evaluation of the residual life of lubricants and optimization of maintenance intervals for internal combustion engines.
  • Ескіз
    Документ
    Improving the wear resistance of guides: tribological analysis, surface texture and lubricants
    (Хмельницький національний університет, 2025) Dykha, O.V.; Dytyniuk, V.O.; Kovtun, O.S.; Fasolia, V.O.; Hetman, M.V.
    The article considers the main failure modes of guides, in particular wear and contact fatigue, which depend on friction between contact surfaces. The influence of tribological parameters, in particular surface roughness and lubricating structures, on the operational characteristics of linear guides is studied. Particular attention is paid to the dynamic behavior of guides, which determines the accuracy and stability of mechanical systems. To predict wear, mathematical models based on the Archard and Hertz theories were used, which allow estimating load distribution and contact deformations. The influence of lubricants, in particular molybdenum disulfide and hexagonal boron nitride, on reducing the friction coefficient and improving antifriction properties was separately studied. The prospects for using new materials, such as cubic boron nitride, to increase the wear resistance of guides are considered. Methods for optimizing the load between rolling elements, which contributes to increasing the durability of guides, are proposed. The results obtained can be used to improve the designs of high-precision mechanical systems and reduce operating costs.