Browsing by Author "Kuzin, Oleg A."
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Item Application of Computational Mechanics Approaches for Increasing of Tribosystem Operational Parameters by using Plasma Hardening Method(Czestochowa University of Technology, Poland, 2021) Kopylov, Viacheslav; Kuzin, Oleg A.; Kuzin, Nickolai O.EN: On the basis of the mathematical model of the continual description of functionalgradient metal systems, taking into account their structure, a computational computer scheme has been developed that makes it possible to assess the stress-strain state of local volumes of parts taking into account their spatial inhomogeneity. With the use of modern software components of computational mechanics – FEniCS finite element analysis package and its implementation in Python, the optimal structural characteristics of wheelsets of railway locomotive tires after plasma treatment have been established. It is shown that, depending on the value of the load, hardening of products must be carried out to a depth of 4.5 mm; with a further increase in thickness, the parameters of operational strength do not change.Item Application of the Models of Mechanics for the Evaluation of the Microstructural Parameters of Alloys with Elevated Wear Resistance(Springer, US, 2009) Kuzin, Oleg A.; Yatsyuk, Rostislav A.; Kuzin, Mykola O.EN: We show the possibility of application of the approaches of mechanics to the determination of the relative fractions and sizes of phases in antifriction alloys with elevated wear resistance. It is demonstrated that the wear resistance of B16 babbitt increases if its microstructure contains an Sn Sb hardening phase whose size is equal to 53 μm.Item Determination of the Optimal Parameters of the Structure of Functional Gradient Materials using Mathematical Modelling Approaches(International OCSCO World Press, Poland, 2019) Lyashenko, B. A.; Stotsko, Z. A.; Kuzin, Oleg A.; Kuzin, Mykola O.; Mikosianchyk, OksanaEN: Abstract. Purpose: Functioning of mechanical friction systems largely depends on the characteristics of the structure of their surface layers. By controlling these parameters, it is possible to significantly adjust the reliability and durability of parts under the conditions of contact interaction. Design/methodology/approach: he proposed approach, which is based on the principle of nonlocality of the operational properties of materials, allows determining the optimal microhardness values of the surface layers and the gradient of this parameter, at which the contact durability of friction pair elements significantly increases. Findings: It is established that by adjusting the ratios of the surface strength of materials and its gradient, it is possible to achieve a significant increase in the operational parameters of friction units. Practical implications: The engineering relationship considered in the work allows to establish functional distributions of microhardness in the structure of surface layers, at which their wear reaches minimum values. Originality/value: Mathematical approaches are proposed, which allow determining the parameters of the structure of the surface layers of parts to increase their durability under conditions of friction contact loads.Item Estimation of Strength Properties of Functionally Graded Structures with Elliptical Stress Concentrators(International OCSCO World Press, Poland, 2022) Stotsko, Zinoviy A.; Kuzin, Oleg A.; Kuzin, Mykola O.; Mechnik, V. A.ENG: Purpose: The purpose of this paper is to elaborate new calculation schemes for evaluating the strength parameters of railway rolling stock parts with non-local properties of surface layers in the presence of elliptical stress concentrators. Design/methodology/approach: Using the proposed approaches of developed mathematical modelling and open software for calculating FEniCS, it were established the most dangerous angles of stress concentrator orientation and the required thickness of the hardened zones of parts, which ensures their minimum softening during operation. Findings: It is shown that for an elliptical stress concentrator with any orientation angle, there is a certain key size of surface hardening thickness, the exceeding the value of which does not have influence on the operational strength of the parts, but rise the price of technological operations. Research limitations/implications: In this paper proposes a method for computation the impact of the orientation of the surface elliptical stress concentrators on the contact strength of parts under conditions of dominate friction power loads. Practical implications: The obtained results were used to set the modes of plasma hardening, which increase the contact strength of railway parts with elliptical stress concentrators. Originality/value: Using the approaches of contact mechanics, mathematical and computer modelling, methods of controlling the contact strength of the parts with the surface elliptical stress concentrators were proposed for the first time.Item Improving Contact Durability of Polycrystalline Systems by Controlling the Parameters of Large-Angle Grain Boundaries(НВП ПП «Технологічний Центр», Харьків, 2019) Kopylov, Vyacheslav; Kuzin, Oleg A.; Kuzin, Nickolai O.EN: ABSTRACT: Polycrystalline metal systems in the samples made of steel 40X with different morphology and parameters of the distribution of large-angle grains boundaries for energy have been examined. The effect of the structural-energy state of grains boundaries on the operational reliability of improved steel 40X has been established. Based on the hierarchical modeling of polycrystals structure, new approaches have been proposed and algorithms have been developed for defining relationships between the structure that is formed in the technological processing of materials and stages in the life cycle of parts. It has been revealed that it is advisable to use, as a digital prototype of the structure of polycrystalline alloys that describes their performance under conditions of contact loads, the matrix representation of a system model that would incorporate the quantitative characteristics of grains. By using the devised procedures, the ways to execute technological control over the energy state of grain boundaries in the structural components have been defined in order to improve durability of parts exposed under contact loads. An estimation-experimental method has been developed to assess the effect of quantitative characteristics of the structure on the parameters of strength of the grains boundaries and their ability to form intragrain damage under external loads. The energy level of grains boundaries and triple joints between the groups of small and large grains is higher than that between grains of the same size. The boundary surfaces with a high level of energy are places where damage occurs at technological processing and under external loads on structural materials. This points to the crucial role of large-angle boundaries placed between triple joints with a high energy gradient in the process of forming microstructurally short cracks and intragrain destruction of polycrystalline systems. The use of hierarchical modeling methods and computational materials science makes it possible to improve the operational reliability of articles by choosing the optimal parameters for internal boundary surfaces. The lower cost of the parts' life cycle is achieved by thermal treatment regimes, which alter the quantitative characteristics of the steel structure.Item Improving the Energy Efficiency of Operation of Elements of the Structures of the Rolling Stock by Means of Surface Engineering(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Kopylov, Vyacheslav; Kuzin, Oleg A.; Kuzin, Mykola O.EN: Abstract. The manufacture of rolling stock components with a given life cycle based on the computerization of all design and production stages is the most promising way to increase the energy efficiency of its operation. The implementation of this approach requires the expansion of the use of technologies that provide parts with a high level of mechanical and operational properties. The state of the surface layers is important in the formation of the reliability parameters of high-loaded parts. The principles of using system approaches for the physical justification of the choice of the optimal modes of engineering grain boundaries depending on the operating conditions of products are presented. New approaches and algorithms have been created that allow quantitative and qualitative studies of the effect of technological treatments and the chemical composition of polycrystals on the strength of grain boundaries and the processes of softening of the boundary zones. Using the developed techniques, the ways to control the energy state of the internal interfaces by doping, microalloying and heat treatment were determined to increase the resistance to brittle fracture and wear of the steels used in the manufacture and repair of rolling stock.Item Influence of the Modes of Laser Alloying on the Parameters of Wear Resistance of 12Kh17T Steel(Springer, US, 2011) Duryahina, Z. А.; Kuzin, Oleg A.; Kuzin, Mykola O.; Shcherbovs’kykh, N. V.EN: By using the approaches of contact mechanics, we analyze the influence of laser alloying with Nb, B, and Ni on the behavior of the parameters of wear resistance of 12Kh17Т steel. It is shown that, in the process of operation of the components in the case where the force load is much lower than the yield strength of steel, it is reasonable to perform laser alloying by using a CO2 -laser with a power of 800 W. At the same time, in the case where the load is equal to the yield strength, it is reasonable to apply a laser with a power of 6.5 kW which increases the contact strength of the subsurface layers.Item The of Mathematical and Computer Modelling in Solving the Problems of Rail Transport Expert Examination(Czestochowa University of Technology, Poland, 2016) Kuzin, Nickolai O.; Meshcheryakova, Tatjana N.; Kuzin, Oleg A.; Kurileva, Elena F.; Gordinskaya, Natalia V.EN: The analysis of the current state of expert research of the failure of structural elements of railway rolling stock is presented. On the basis of the approaches of mechanics, mathematical and computer modeling the technique of establishing a mechanism for softening of parts and units of friction in the operation of rail transport is suggested.Item The Optimal Thickness of the Surface Plasma Hardening Layer of Functional-Gradient Parts with Symmetrical Stress Concentrators(Springer, Cham, 2021) Stotsko, Zinoviy A.; Kuzin, Oleg A.; Kuzin, Mykola O.EN: Based on the approaches of continuous mathematical modeling, a computational methodology is proposed for establishing one of the most important operational parameters of surface engineering technologies, which determines the life of parts - the thickness of the hardened layer. For the first time, using non-local models of mechanics and the Fenics finite element analysis package, a scheme for finding the optimal hardening depth of parts depending on the load parameters and characteristics of stress concentrators has been built. Using the example of wheel rims of locomotives, it is shown that in the presence of stress concentrators, the increase in the life cycle of parts is achieved by plasma strengthening to a depth of 2.5… 3.5 times larger than the radius of the concentrators. The methodology proposed in the work is necessary for describing the behavior of the material of parts under the action of force loads in the presence of stress concentrators for selecting the optimal technological modes of hardening the surface layers. The established relationship between the change of properties of local volumes of wheels of locomotives at operational loadings and characteristics of concentrators of tension is used to obtain products with the defined life cycle, computer designing of the technological process of plasma strengthening of surfaces of contact interaction of details.Item Specific Features of Fracture of Improved 40Kh SteeL Under Conditions of Contact Interaction(Springer US, 2001) Kuzin, Oleg A.; Bespalov, S. A.; Meshcheriakova, Tetiana M.EN: Investigations of the effects of the quenching temperature and tempering conditions show that the development of a dispersion in grain sizes and precipitation of carbides along the boundaries of grains and subgrains decrease the wear resistance of 40Kh steel. Quenching from 1050°C and elimination of the development of temper brittleness enable one to obtain a microstructure that increases the serviceability of friction units.Item Use of Modern Tribology Approaches for Correcting the Behaviour of Adaptive Biomechanical Friction Units(International OCSCO World Press, Poland, 2018) Stotsko, Z. A.; Kuzin, Oleg A.; Kuzin, Mykola O.EN: Purpose: Functioning of mechanical system friction units is characterized by the ability of their self-adaptation under the influence of external loads. Referring to this phenomenon it becomes possible to provide the necessary correction of the work of friction units being parts of artificial and natural tribosystems. Design/methodology/approach: As an approach used to solve the above problem, an expansion of the function describing friction unit parameters in a given basis with further refinement of the solution in accordance with the functional optimization is proposed. Findings: The received ratios allow solving the problem of adaptive control of friction units functioning when they are incorporated into the biomechanical systems. Practical implications: Using approaches developed in the present work, a pattern for the gradual adjustment of instep supports for the restoration of normal weight distribution in the human foot is presented. Originality/value: Novel approaches to the methodology of solving the problem in regard of managing the load condition of biomechanical tribosystems by their commanded control over time are offered.