Problems of Tribology = Проблеми трибології
Постійне посилання на фонд
Переглянути
Перегляд Problems of Tribology = Проблеми трибології за Автор "Dykha, M."
Зараз показуємо 1 - 4 з 4
Результатів на сторінці
Налаштування сортування
Документ Determination of the dynamic hardness of greases as a characteristic of deformation properties in a tribocontact(Хмельницький національний університет, 2022) Dykha, O.; Staryi, A.; Dytyniuk, V.; Dykha, M.; Диха, О.В.; Старий, А.Л.; Дитинюк, В.О.; Диха, М.О.The efficiency of plastic oil is determined by the duration of its retention on the surface. Evaluation of the effectiveness of plastic lubricants depends on their mechanical properties. It is proposed to use the dependence of hardness on time when pressing a spherical indenter as one of the basic characteristics of the mechanical properties of plastic oils. The method of determining the function of oil hardness is based on the mechanics of contact interaction of a solid ball and a plane presented in this work, which has the property of creep according to the flow theory. One of the main methods of testing the deformation properties of plastic lubricants is to determine the number of penetrations. The number of oil penetrations is determined by the depth of indentation of the indenter; more informative for such a process is the ultimate pressure (hardness), which actually reflects the phenomenon of resistance to indenter indentation in the material. For uniform distribution of pressure under a spherical indenter the technique of construction of function of dynamic hardness of plastic materials is defined and on the basis of tests results of construction of dynamic hardness are received. Tests on contact creep of plastic lubricants are carried out, functions of dynamic hardness are received and the analysis of influence of character of change of dynamic hardness on wear processes in the presence of lubricants is carried out. To analyze the influence of deformation properties on the tribological properties of lubricants, comparative tests of the two above-mentioned types of lubricants on a four-ball friction device were performed. It was found that Litol-24 oil has the best wear resistance. The nonlinear period of running-in for this oil is practically absent that, obviously, under the given conditions of tests is connected with more stable in time deformation properties.Документ Modeling of contact stresses and evaluation of wear life of a valve mechanism guide with lubricating grooves(Хмельницький національний університет, 2024) Holenko, K.; Vychavka, A.; Dykha, M.; Dytyniuk, V.Valve guides are crucial for maintaining proper alignment, positioning, and valve stem clearance as it moves in the cylinder head. Valve bushings are subjected to load and sliding friction; with excessive wear of the guides, the engine begins to consume oil and the valve mechanism becomes noisy. This paper proposes the use of a special knurling to restore and increase the wear resistance of guide bushings. The profile tool is designed to restore valve guides by rolling a spiral groove on the inner surface of the sleeve. After applying this technology, a spiral oil-retaining profile remains on the surface of the sleeve bore. . Using the Solid model, the effect of changing the geometry of the guide bore by the lubricating grooves on the maximum and average stress indices in the guide-valve contact was analyzed. It was found that the maximum stresses of the model with grooves are lower than those of the model with a smooth guide surface. Based on the finite element model, the durability of the valve-guide pair with oil-retaining grooves was analyzed and it was determined how many cycles the contact surface of the guide can withstand. It was established that by reducing the contact pressure, the actual resource of the guide with grooves increased.Документ Modeling surface structure of tribotechnical materials(Хмельницький національний університет, 2024) Drach, I.; Dykha, M.; Babak, O.; Kovtun, O.Modern tribology makes it possible to correctly calculate, diagnose, predict and select appropriate materials for friction pairs, to determine the optimal mode of operation of the tribo-joint. The main parameter for solving friction problems and other problems of tribology is the topography of the surface. The main purpose of the models in these tasks is to display the tribological properties of engineering surfaces. In the framework of the classical approach, the topography of the surface is studied on the basis of its images from the point of view of functional and statistical characteristics: the evaluation of the functional characteristics is based on the maximum roughness along the height and the average roughness along the center line, and the statistical characteristics are estimated using the power spectrum or the autocorrelation function. However, these characteristics are not only surface properties. They depend on the resolution of the device for measuring the surface geometry and the length of the scan. However, the degree of complexity of a surface shape can be represented by a parameter called the fractal dimension: a higher degree of complexity has a larger value of this parameter. Fractal dimensionality is a characteristic of surface relief and makes it possible to explain tribological phenomena without the influence of resolution. This article provides an overview of mathematical approaches to the description of the relief of engineering surfaces, in particular statistical, stochastic and topological modeling, their limitations, advantages and disadvantages. The implementation of the principles of the theory of fractal structures is discussed, which makes it possible to introduce the degree of imbalance of the tribological system into the analysis of structure formation in the surface and near-surface layers of materials and to describe the development of friction and wear processes. This is the basis for controlling the structure of the surface layers of materials with given properties. The concept of fractals, used for the quantitative description of the dissipative structure of the tribojunction zone, makes it possible to establish a connection between its fractal dimension and mechanical properties, as well as critical states of deformation of metals and alloys. The course of research and stages of fractal modeling, the classification of methods of fractal analysis of the structure of engineering contact surfaces are considered. A critical analysis of modern models based on the energy-spectral density function, which are quite similar to fractal models, is presented. Readers are expected to gain an overview of research developments in existing modeling methods and directions for future research in the field of tribology.Документ Simulation model of contact interaction during surface strengthening of steel parts(Khmelnytskyi National University, 2023) Holenko, K.; Dytyniuk, V.; Dykha, M.In the processes of surface strengthening of steel parts, the stress-strain state is decisive for explaining the physical processes of strengthening, forming the dimensions of the contact area. Analytical dependences of contact parameters are quite approximate. In this work, based on the Ansys software complex, a simulated model of the contact of a truncated torus with a cylinder is proposed, which demonstrates the kinetics of the process of pressing a hard alloy tool into a steel workpiece - a cylinder. The experiment was conducted for 4 seconds in order to determine the maximum level of stresses, the distribution of stresses and the amount of residual stresses after removing the load. The clamping force was applied mainly in the zone of elastic deformations. The results showed an uneven stress distribution with a maximum in the center of the contact spot of 1082 MPa. After changing the load direction, small residual deformations at the level of 0.00311 μm were observed in the center of the contact patch. This indicates a violation of the elastic region on a small contact area, which does not affect the general nature of the stress distribution and can be removed during the finishing process. The results of simulation of the stressed state are used for the correlation with the observed structural changes of the material during the action of thermal and power stresses. The stress peak was formed at a distance of 200 μm, which contributes to the formation of maximum values of microhardness at this depth.