Browsing by Author "Kuzin, Mykola O."

Now showing 1 - 9 of 9
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    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.
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    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, Oksana
    EN: 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.
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    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.
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    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.
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    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.
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    Influence of the Structure of Babbitt on the Stress-Strain State in the Zone of Friction Contact
    (Springer, US, 2007) Burak, Ya. I.; Kuzin, Mykola O.
    EN: The methods of mathematical simulation are used to study the process of contact friction interaction for homogeneous lead and heterogeneous intact or run-in B16 babbitt. It is shown that the hard and soft structural components of the run-in babbitt strongly decrease the size of the zones of plastic deformation in the material, improve its wear resistance, and promote the increase in the operating reliability and service life of plain bearings.
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    Life Cycle Assessment of Technical Systems Taking into Consideration Degradation Processes in Materials of Constructions
    (International OCSCO World Press, Poland, 2018) Stotsko, Z. A.; Kuzin, Mykola O.
    EN: Purpose: In the engineering analysis and transport forensic examination, there are often arise problems in establishing the causes and mechanism for the destruction of structural elements. At the moment, such problems are poorly formalized and practically do not take into account the degradation of the material and the gradient of its properties when destroyed. The purpose of this article was to build a methodology for determining the distribution of material properties at the initial time and establishing its compliance with the requirements of regulatory documentation. Design/methodology/approach: As a technique for solving the problem, was proposed the expansion of a function in a given basis with subsequent refinement of the solution using iterative algorithmic schemes. Findings: Using the developed approaches, it is established that in the surface layers of 12X18H10T steel (AISI 321), after technological modification under the conditions of laser doping, functional-gradient layers are formed with the material viscosity level characteristics at 0.8, which corresponds to the established norms, and their destruction occurred as a result of excessive loads. Practical implications: With the using of the developed methods makes it possible to solve the problem of technical forensic examination to determine compliance to the requirements the properties of functional gradient materials in initial time. Originality/value: The technique of solving inverse problems of fracture mechanics for functional gradient materials is shown for the first time.
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    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.
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    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.