As a result of the dissertation work, the actual scientific and applied problem of creating models for predicting the wear resistance and reliability of bearing tribosystems and optimizing the technological parameters of the discrete-oriented strengthening method was solved.
Connection of work with scientific programs, plans, topics: "Theoretical-experimental methods and computer models of ensuring the survivability of cylindrical sliding tribosystems under normal and high-speed friction (No. DR 0116U001549), 2016; "Prediction of wear resistance and reliability of bearing assemblies and optimization of their parameters" (No. DR 0120U102070), 2020.
The object of research there are processes of wear of parts of bearing tribosystems and their strengthening.
The subject of research there are computational and experimental models of wear resistance and reliability of bearing tribosystems and technological parameters of a discrete-oriented method of strengthening their parts.
The purpose of the dissertation is the creation of computational and experimental models for predicting the wear resistance and reliability of bearing tribosystems and substantiating the technological parameters of the discrete-oriented method of strengthening their parts based on electromechanical strengthening.
The scientific novelty of the obtained results is as follows:
1. For the first time, the effect of local electrical contact cementation with simultaneous surface hardening due to the combined effect of a roller electrode on a steel shaft through a carbon layer during the rolling of discretely located strengthening areas was experimentally proven.
2. To assess the effect of discrete strengthening on the formation of the stress state of the surface layer, a new two-stage simulation computer model was built, which includes the strengthening (profiling) stage with the subsequent formation of contact interaction with the coupled surface-press, which is close to the real conditions of operation of tribocouplers.
3. The method of solving the direct wear-contact problem for a sliding bearing on the basis of approximate transformations of trigonometric functions was further developed, which made it possible to obtain solutions for wear in a closed form.
4. An improved theory of the tribological test method for identifying wear resistance parameters of the sliding bearing tribosystem, which is characterized by the use of new dimensionless forms of wear models for the "cone-three ball" contact scheme.
The practical significance of the obtained results lies in the recommendation for the application at machine-building enterprises and design institutions of the methods of predicting the wear resistance and reliability of bearing tribosystems. The results of the dissertation research were implemented at the Khmelnytskyi communal enterprise "Electrotrans", in the department of automotive technical expertise of the Khmelnytskyi Scientific and Research Expert and Forensic Center, as well as in the educational process of the Khmelnytskyi National University.
The first section analyzes the current stage of development of technological means of increasing the durability of machines. On the basis of the analysis of studies of strengthening methods, significant advantages of surfaces subjected to not continuous strengthening, but discrete strengthening, were established. In the second section, the methodology of calculation-experimental assessment of wear resistance and tribotechnical reliability of friction units of machines is considered. In the third section, a combined discrete-oriented method of strengthening cylindrical surfaces of tribosystems is proposed. A kinetic computer experiment was carried out to simulate the natural load when modeling the contact interaction of the roller and the shaft during discrete strengthening. Structures were analyzed and indicators of microhardness of discrete-reinforced layers were studied in order to prove their effectiveness. In the fourth section, the solutions of direct and inverse wear-contact problems for the calculation of wear with known parameters of wear resistance are given, the dependencies for the identification of these parameters are determined. A calculated assessment of the wear and reliability of the bearing supports of the camshaft was carried. In the fifth chapter, a finite-element model of the investigated camshaft bearing assembly is constructed. The method of bench tests of the bearings of the gas distribution mechanism of the internal combustion engine was developed and implemented.
Key words: tribosystem, bearing, hardening, coating, microhardness, wear, modeling, carbon, contact problem, surface layer, reliability, test, shaft
