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1

Estimation of strength properties of functionally graded structures with elliptical stress concentrators

Stotsko Z.A., Kuzin B., Kuzin M.O., Mechanik V.A.

Archives of Materials Science and Engineering

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2022

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Vol. 113, nr 1

35--41

EN

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.

2

The use of computational contact mechanics approaches to assess the performance of parts bearing stress concentrators

Lyashenko B. A., Stotsko Z. A., Kuzin O. A., Kuzin M. O.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 103, nr 1

25--32

EN

Purpose: The purpose of this work is to build new computational schemes for assessing the strength parameters of parts with inhomogeneous properties of surface layers in the presence of stress concentrators. Design/methodology/approach: Using the developed approaches of mathematical modeling and open software for calculating the structures of the FEM - FEniCS, the required thickness of the hardened zones of parts has been established, which ensures their minimum softening during operation, depending on the characteristics of the stress concentrator. Findings: It is shown that for each size of the surface stress concentrator there is a critical value of the hardening thickness, the excess of which does not affect the operational strength of the parts, but increases the cost of technological operations. Research limitations/implications: In this article proposes a method for calculating the influence of the dimensional characteristics of hardening zones on the contact strength of parts with stress concentrators under conditions of prevailing power loads. Practical implications: The results obtained in this work were used to determine the technological modes of plasma hardening, which ensure an increase in the contact strength of parts with stress concentrators, depending on their dimensional characteristics. Originality/value: Using the approaches of computational mechanics and mathematical and computer modeling, methods for controlling the contact strength of parts with inhomogeneous non-local properties in the presence of a surface stress concentrator are proposed for the first time.

3

Analysis of friction interaction and optimisation of detail surface hardening technologies using non-local mathematical models

Lyashenko B. A., Stotsko Z. A., Kuzin O. A., Kuzin M. O., Mechnik V. A.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 100, nr 1

20--25

EN

Purpose: The aim of the work is to build physically sound engineering and design schemes that take into account the behaviour of polycrystalline metal systems under intense loads and allow optimization of surface treatment technologies to increase the operational reliability parameters of products. Design/methodology/approach: Using the approaches of thermodynamics, a methodological scheme is proposed, on the basis of which it is possible to optimize surface engineering technologies to increase the contact durability of details. Findings: It was found that the maximum increase in the durability of steel 40X13 (AISI 420) is achieved with thermocyclic ion nitriding in a cycle of ± 50°C, and the minimum with isothermal nitriding. Research limitations/implications: In this paper, the optimization of technological solutions to increase the contact durability of structural elements operating under prevailing power loads is given. Practical implications: Using the proposed mathematical relationships, optimal technological regimes of ion-plasma nitriding were established for various operating conditions, under which the maximum durability and wear resistance of 40X13 (AISI 420) steel are ensured. Originality/value: The paper proposes an approach to the formation of functionally gradient surface layers of steel with specified operational parameters when choosing optimal nitriding technology modes based on nonlocal mathematical models.

4

Determination of the optimal parameters of the structure of functional gradient materials using mathematical modelling approaches

Lyashenko B. A., Stotsko Z. A., Kuzin O. A., Kuzin M. O., Mikosianchyk O. A.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 92, nr 1-2

13--18

EN

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.

5

Use of modern tribology approaches for correcting the behaviour of adaptive biomechanical friction units

Stotsko Z. A., Kuzin O. A., Kuzin M. O.

Archives of Materials Science and Engineering

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2018

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Vol. 92, nr 2

49--52

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.

6

Modelling of abrasive blasting technological modes for curvilinear surfaces of machine parts

Stotsko Z. A., Stefanovych T. O.

Przetwórstwo Tworzyw

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2013

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[R.] 19, nr 1 (151)

54--57

EN

An expression for determining the glancing impact angle for a point on the curvilinear surface of machine parts for abrasive blasting is obtained. It allows to estimate the distribution of kinetic energy of working medium all along the treated surface and, therefore, the surface quality parameters.

7

Influence of pulse laser irradiation on structure and mechanical properties of amorphous Fe73.1Nb3Cu1.0Si15.5B7.4 alloy

Mudry S.I., Nykyruy Yu.S., Kulyk Yu.O., Stotsko Z. A.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 61, nr 1

7--11

EN

Purpose: The aim of this work was to study structure changes in Fe-based amorphous ribbon under laser radiation, determine it dependence from laser treatment parameters and establish the correlation between structure and microhardness. Design/methodology/approach: Amorphous ribbons of Fe73.1Nb3Cu1.0Si15.5B7.4 alloy, obtained by rapid cooling from the melt, has been treated by pulsed laser radiation with wavelength λ = 1.06 μm and pulse duration τ = 130 ns. Structure transformation has been studied by means of X-ray diffraction method, which allowed us to determine the phase composition, volume fraction and grain size of crystalline phases has been determined. Findings: It has been shown, that laser treatment method allows forming an amorphous-nanocrystalline composite. It was found that microhardness of ribbon increases after irradiation and linearly depends on percent of crystalline phase. Practical implications: Laser treatment can be used as an substitute of isothermal heat treatment to produce amorphous-nanocrystalline materials with improved properties. Originality/value: The originality of this work is based on applying of pulse laser irradiation for modifying structure of amorphous Fe73.1Nb3Cu1.0Si15.5B7.4 alloy.

8

Effect of ultrasonic treatment of activated carbon on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors

Venhryn B. Y., Grygorchak I.I., Stotsko Z. A., Bakhmatyuk B.P., Mudry S.I., Kulyk Yu.O.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 60, nr 2

59--65

EN

Purpose: Use of ultrasonic radiation for improving the properties of activated carbon was the aim of this paper. Increase of density of states at Fermi level was the main factor, responsible for working characteristics of electrochemical supercapacitors. Design/methodology/approach: Working parameters of supercapacitors on the base of activated carbon have been studied by means of precisional porometry, small angle X-ray scattering, cyclic voltamerometry, electrochemical impedance spectroscopy and computer simulation methods. Findings: The possibility to effect the interface between activated carbon and electrolyte by means of ultrasonic treatment in cavitation and noncavitation regimes is proved. It is shown that ultrasonic treatment in noncavitation regimes causes the significant increase of density of states at Fermi level that results in better farad-volt dependences. Research limitations/implications: This research is a complete and accomplished work. Practical implications: Modification of electric double layer by meanans in ultrasonic treatment, proposed in this work, could be regarded as effective way to obtaine the advanced electrode materials in devices of energy generation and storage. Originality/value: This work is important for physics, material science and chemistry because it is related with new possibilities to change the mobility of charge carries in electric double layer by means of ultrasonic irradiation.

9

New trends in nanoscale compounds for energy storage

Stotsko Z. A., Venhryn B.Ya.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 54, nr 2

227--232

EN

Purpose: Mechanism of supramolecular complexes C formation and investigation of their electrochemical characteristics were the aim of this paper. Supramolecular complexes were created by inserting an organic receptor into nano/mesopores of activated carbon. Design/methodology/approach: Electrochemical studies of supramolecular complexes C were carried out by means of impedance spectroscopy, cyclic voltammetry and galvanostatic cycling. Findings: The possibility to combine the capacitive storage with faradaic energy generation in one unit is proved. It can be reached by means of active electrode formation as a supramolecular complex C. It is shown that faradaic generation of energy occurs at low positive potentials, whereas the capacitive one at higher potentials. Method of synthesis of blue graphite is developed. Research limitations/implications: This research is a complete and accomplished work. Practical implications: Supramolecular complexes, obtained in this work, could be regarded as promising electrode materials in devices of energy generation, storage and transformation. Originality/value: This work is of urgent importance for physics and chemistry of energy generation, storage and transformation, because it opens new possibilities to new highly effective electrode materials search and enables to reach a high values of functional characteristics.

10

Surface layer modelling and diagnostic after loose solid balls treatment

Stotsko Z. A., Stefanovych T. O.

Przetwórstwo Tworzyw

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2011

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[R.] 17, nr 6

529-533

EN

Purpose of this paper is development of the mathematical models of the methods of treatment with using loose solid balls. The main methods used for the theoretical research are mathematical modelling, integral calculus, fundamentals of analytic geometry, probability theory, hydraulics of multiphase flow. The main methods used for the experimental investigations were conducted by receiving diagrams of removed material depth, microhardness of the oblique slices of the treated samples, speckle interferograms of the surfaces treated with using loose solid balls. Method of mathematical modeling for treatment with using loose solid balls is developed based on the energy conception. Mathematical model is created that allows calculating the characteristics of surface quality depending on the technological modes of the treatment. It is planned developing and improving the mathematical modeling methods of the treatment with using loose solid balls in future research by extending theirs for the curvilinear treated surfaces. Practical implications has the applied software, elaborated on the models basis, that allows providing for calculations automation of the surface quality characteristics depending on the technological modes.

11

Investigations on the machine parts treatment by non-bound blast particles

Stotsko Z. A., Stefanovych T. O.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 49, nr 2

440--459

EN

Purpose: of this paper is development of the mathematical models of the methods of treatment by non-bound blast particles. Analysis of non-bound blast particles behavior is carrying out for modeling. The operating factors such as geometrical parameters of a nozzle, distance to the treated surface, and pressure of compressed air and outlet factors such as level of strengthening, depth of hardened layer are determined. It is proposed to put into basis of the mathematical models the energy conception that permits the unification and simplification of mathematical description of the processes. The level of strengthening, and depth of hardened layer are estimated for the plain surfaces by means of created mathematical models. Design/methodology/approach: The main methods used for the theoretical research are mathematical modelling, integral calculus, fundamentals of analytic geometry, probability theory, hydraulics of multiphase flow. The main methods used for the experimental investigations were conducted by receiving diagrams of surface roughness, microhardness of the oblique slices of the treated samples, speckle interferograms of the surfaces treated with the use of non bound blast particles. Findings: Method of mathematical modeling for treatment by non-bound blast particles is developed based on the energy conception. Mathematical model is created that allows calculating the characteristics of surface quality depending on the technological modes of the treatment. Research limitations/implications: It is planned to develop and improve the mathematical models in future research by extending them for the curvilinear treated surfaces, which has movement relative to the nozzle. Practical implications: has the applied software, elaborated on the basis of the models, that allows providing for automation of calculations of the characteristics of surface quality depending on the technological modes of the treatment. Originality/value: It is pioneered receiving functional dependences between the depth of hardening layer, changing of microhardness, degree of hardening and the parameters of equipment, blast, and working medium. Created functional dependences takes into account the distribution of characteristics of working medium (mass and velocity) all along the cross-sections of the blast.

12

Hyper capacity of MCM-41 supramoleculer structure in the radiofrequency range

Grygorchak I. I., Vojtovych S. A., Stotsko Z. A., Seredyuk B. A., Tovstyuk N. K.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 49, nr 2

200--203

EN

Purpose: of this paper was: 1) to synthesize supramolecular MCM-41 structure (p-cyanogen phenyl ether of n-heptyl benzoic acid - 40%)>> with inserted guested nematic and 2) to study its dielectric properties. Design/methodology/approach: Supramolecular MCM-41 structure has been synthesized by vacuum encapsulated method at room temperature. Dielectric properties have been studied by impedance spectroscopy method in the frequency range 10-3-106 Hz by “AUTOLAB” complex of “ECO CHEMIE” (Holland), supported by computer programs FRA-2 and GPES. Findings: We have found a tremendous increase of the permittivity and a low value of the tangent of angle of electric losses, as well as the appearance of low frequency inductive response. Practical implications: Super high capacitors of radio range and time-delay lines allow to use them in a direct incorporation into nanoelectronics devices as a new class of super high capacitors and nanostructured time-delay lines. Originality/value: First time we have received: 1) supramolecular structure of the configuration of molecular-lattice nonorganic matrix with a non nematic substrate, 2) significant inductive response in such structures.

13

Strengthening surfaces of machine components by treatment using loose solid balls

Stotsko Z. A., Stefanovych T. O.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 40, nr 2

195-202

EN

Purpose of this paper is to develop mathematical models of the treatment methods using loose solid balls. Analysis of treatment with the use of loose solid balls behaviour is carried out for modelling. The operating factors such as geometrical parameters of a nozzle, distance to the treated surface, and pressure of compressed air and outlet factors such as level of strengthening, depth of hardened layer are determined. It is proposed to put into basis of the mathematical models the energy conception that permit for unification and simplification of mathematical description of the processes. The level of strengthening, and depth of hardened layer are estimated for the plain surfaces by means of created mathematical models. Design/methodology/approach: The main methods used for the theoretical research are mathematical modelling, integral calculus, fundamentals of analytic geometry, theory of probability, hydraulics of multiphase flow. The main methods used for the experimental investigations were conducted by receiving diagrams of surface roughness, microhardness of the oblique slices of the treated samples, speckle interferograms of the surfaces treated using loose solid balls. Findings: A method of mathematical modelling for treatment with the use of loose solid balls is developed based on the energy conception. The mathematical model is created and allows calculating the characteristics of surface quality depending on the technological modes of treatment. Research limitations/implications: It is planned to develop and improve the methods of mathematical modelling of the treatment using loose solid balls in future research by extending them for the curvilinear treated surfaces, which are characterised by a movement relative to the nozzle. Practical implications: have the applied software, elaborated on the basis of the models, that allows providing for automation of calculations of the characteristics of surface quality depending on the technological modes of the treatment. Originality/value: It is pioneered to receive functional dependences between depth of a hardening layer, changing microhardness, degree of hardening and the parameters of equipment, blast of loose solid balls, and working medium. The created functional dependences take the distribution of characteristics of working medium into account (mass and velocity) all along the cross-sections of the blast.

14

Ensuring uniformity of strengthening for machine parts surfaces by shot-peening

Stotsko Z. A., Stefanovych T. O.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 1

440--447

EN

Purpose: of this paper is developing the mathematical models of shot-peening, in which is reflected moving shot-peening head or machine parts surfaces during treating that will achieve uniformity of treatment machine parts. Design/methodology/approach: The main methods used for the theoretical research are mathematical modelling, integral calculus, fundamentals of analytic geometry, probability theory. It is used approved enough and well known numerical methods for calculations after mathematical models. Findings: Method of mathematical modeling for shot-peening is developed based on the energy conception. Mathematical model in which is reflected moving shot-peened head or machine parts surfaces during treating is created. It allows forecasting the characteristics of surface quality depending on the technological modes of treatment. Research limitations/implications: It is planned developing and improving the methods of shot-peening mathematical modeling in future research by extending theirs for the curvilinear treated surfaces, which has movement relative to the nozzle of shot-peening head after the different laws of motion, and for different kinds of materials, especially for metal joint endoprosthesis biomaterials. Practical implications: has the applied software, elaborated on the basis of the models, that allows providing for automation of calculations of the characteristics of surface quality depending on the technological modes of treatment. Originality/value: It is pioneered receiving functional dependences in which is reflected moving shot-peened head or machine parts surfaces during treating. Created functional dependences takes into account the distribution of characteristics of working medium (mass and velocity) all along the cross-sections of shot blast.

15

Complex mathematical model and optimisation of vibration volumetric treatment for surfaces of machine parts

Stotsko Z. A., Sokil B. I., Topilnytskyy V. G.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

283-290

EN

Purpose: The objective of this work is to develop the principles of the theoretical investigation of vibration volumetric treatment for the surfaces of articles manufactured by friable dry medium and to create the method for choice and optimization of machine parameters. Design/methodology/approach: Theoretical investigations are based on using the analytic methods of theory of non-linear oscillations and asymptotic methods of solving non-linear differential equations for describing dynamic processes of volumetric vibration treatment. Experimental investigations of dynamic processes that take place in the vibromachines were carried out with using the computer and vibration measuring system. Findings: Complex non-linear mathematic model of the system "vibromachine - treating medium" is created. Due to their non-linearity, models of such kind are adequate to real situation of vibrotreatment, they can also be applied in investigation of dynamics of the vibromachine and its medium. Research limitations/implications: Processes of vibration volumetric treatment need additional investigations. Practical implications: The obtained complex mathematical model of the system "vibromachine - trading medium" enables us to analytically determine the influence of its parameters upon the intensity of articles treatment in it according to the chosen criterion; thus it saves us from carrying out time taking cumbersome experiments both for designing a vibromachine and for selecting modes of treating articles in it. Originality/value: The new approach to the investigations of volumetric vibration treatment by means nonlinear mathematic model of the system "vibromachine - treating medium" have been shown.

16

Influence of vibratory-centrifugal strain hardening on surface quality of cylindric long-sized machine parts

Stotsko Z. A., Sokil B. I., Kusyy M. J., Topilnytskyy V. G.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

25--30

EN

Purpose: The objective of this work is to develop mathematical models based on experimental data that enables us to predict the values of physico-mechanical parameters of surface quality of MLSMP (microhardness, depth of hardened layer, level of hardening) when VCSH is applied. Design/methodology/approach: For all round studying of the effect of main technological factors on physico-mechanical parameters of MLSMP surface layer quality (microhardness, depth of hardening layer, level of hardening) it is expedient to use the method of factor planning with applying plane 2k, where k is the number of variation factors. Findings: The obtained empiric relations enable us to predict the values of physico-mechanical parameters of MLSMP made of alloyed steels (especially of 40XH2MA steel) depending technological parameters of VCSH, the parameters being within their ranges. Research limitations/implications: The effect of technological parameters of VCSH and that of constructional dimensions of the hardening device equipped with electromagnetic drive and elastic system parameters of MLSMP surface hardening qualities is ambiguous. Originality/value: The hardening devices equipped with electromagnetic drive and elastic systems for treating internal and external MLSD surfaces are designed to solve the problem.