Problems of Tribology = Проблеми трибології - 2019 рік
Постійне посилання зібрання
Переглянути
Нові надходження
Документ A flat contact problem the interaction two prestressed stripes with an infinite stringer(Khmelnytskyi National University, 2019) Dikhtyaruk, N.N.; Poplavskaya, E.A.The article is devoted to the research of problems of contact interaction of infinite elastic stringer with two identical clamped along one edge of pre-stressed strips. In general, the research was carried out for the theory of great initial and different variants of the theory of small initial deformations within the framework of linearized theory of elasticity with the elastic potential having arbitrary structure. The integral integer-differential equations are obtained using the integral Fourier transform. Their solution is represented in the form of quasiregular infinite systems of algebraic equations. In the article alsaw was investigated the influence of the initial (residual) stresses in strips on the law of distribution of contact stresses along the line of contact with an infinite stringer. The system is solved in a closed forms using transformation of Fourier. Expressions of stresses are represented by Fourier integrals with a simple enough structure. Influence of initial stress on the distribution of contact stresses is study and discovered the mechanical effects under the influence of concentrated loads.Документ Fuel of the keeping needs of the energy discharge during nitrogen on the tribological chara(Khmelnytskyi National University, 2019) Stechyshyna, N.M.; Stechyshyn, M.S.; Martyniuk, A.V.The effect of power discharge category W in BATR on tribological characteristics of nitrous steel 45 is investigated in the work. The highest wear resistance of steel 45 corresponds to mode 7, which provides optimum physico-chemical characteristics of the nitrided layer. The ratio of the intensities of the passage of the main BATR subprocesses determines the structure and phase composition of the nitrided layers. Depending on the current combination of parameters of the mode of formation of the nitrided layer, the intensity of the flow of the above subprocesses (nitride formation, sputtering and diffusion saturation of the surface with nitrogen), and therefore the intensity of the formation of certain phases may be different, and sometimes reverse. For example, as the energy of the incident stream W increases, the pre-formed nitride layer is sprayed, which stimulates the process of nitrogen diffusion into the metal base and the formation of ε and γ - phases. When the flow energy is insufficient to atomize the nitride layer, it acts as a kind of barrier that impedes or completely stops the process of nitrogen diffusion. It is established that the decrease in the specific discharge power leads to a decrease in the thickness of the nitride and diffusion zones and, as a consequence, the tribological characteristics deteriorate. It is revealed that at the maximum values of energy parameters, a nitrous containing layer is formed ε, γ і α - phase. The decrease in voltage and current density causes the particle to increase γ - pfase (Fe4N) and according to the reduction of the share ε - phase (Fe2N). At minimum values of energy parameters of formation of nitrides on the surface is absent and the nitrided layer consists only of α - phase.Документ Wear resistence of complex electrolitic coatings in electrolite environments(Khmelnytskyi National University, 2019) Bilyk, Yu.M.; Martyniuk, A.V.; Medvedchuk, N.K.; Kupets, B.I.The technology of formation of wear-resistant composite electrolytic coatings (CEP) based on nickelbased is presented. CEP. These coatings contained a filler consisting of powders of silicon carbide of various fractions and amorphous boron with a particle size of about 1 μm for further heat treatment. The obtained coatings were tested for their cavitation and erosion resistance in electrolyte mediaДокумент Modern studies of tribological bearing systems: a review(Хмельницький національний університет, 2019) Dykha, O.; Dytynyuk, V.; Posonsky, S.; Zelenska, L.; Дыха, А.В.; Дытынюк, В.А.; Посонский, С.Ф.; Зеленская, Л.И.Sliding bearings are one of the important friction points of modern machines, ensuring their long-term operation. Sliding supports determine the accuracy of the executive movements of the working parts of the machines. Creating and researching reliable and accurate sliding bearings is an important engineering issue. This review presents the results of studies of bearings, published in recent years in specialized scientific journals. The issues of creating efficient structural bearing assemblies, including through the use of new hybrid materials and structures, are considered. Much attention is paid to the problem of bearing wear and reducing the coefficient of friction. Separately considered issues of computer modeling of working conditions and design of structures. Considered modern approaches to the calculated evaluation of bearings, the solution of contact problems. This review allows scientists and engineers to do the right task setting when planning further research on bearing tribo systems.Документ Formation of the characteristics of the energy state in the local contact of the processing and tool materials in the cutting process(Хмельницький національний університет, 2019) Buryak, V.G.; Buryak, A.V.; Buryak, V.V.; Буряк, В.Г.; Буряк, А.В.; Буряк, В.В.The formation of characteristics of the energy state in the local contact of machined and tool materials in the cutting process is performed. The adoption of a model of the choice of unit microniveness in the form of a straight truncated cone is substantiated. The rate of deformation of the machined material on of unit microniveness is determined. The probability of the presence of acoustic oscillation and wave processes that occur in the conventional shear plane during the cutting process is shown. The dependence of the magnitude of unit microniveness area on the roughness parameters is established. Analyzing the dimensions of microniveness, and also taking into account the calculated data of the autocorrelation function of the structural and energy state of the working surfaces of the cutting plates, which in microniveness there is a certain amount of grain of the solid base of the material of the cutting plates. The functional dependences of the conditional number of grains on the size of roughness parameters as well as on the average grain size are established. The obtained research results are the initial data when using the methodology of performance evaluation of cutting tools by analyzing the acoustic characteristics of the energy state of processing and instrumental materials using the differential equation of cause and effect relationship.Документ Contact problem of elastic strips with initial stresses with periodically placed resilient protective strap(Хмельницький національний університет, 2019) Gonchar, V.; Kaplun, P.; Rudyk, O.; Matviishen, P.; Гончар, В.А.; Каплун, П.В.; Рудык, А.Е.; Матвиишин, П.В.The article highlights the results of experimental research of the wear resistance of different structures of steels with different thermal and chemical-thermal treatment in corrosive and abrasive medium on special friction machines that modelled the working conditions of the extrudes when processing feed grain with the additives of saponite. Comparative study showed that metal wear resistance in corrosive and abrasive medium at higher temperatures depends not only on the hardness of friction surface, but also on its structure, phase composition and hardness of gradient change in the depth of the hardened layer. To provide extruder’s high wear resistance when manufacturing feed grain mixed fodder with the additives of saponite it is recommended to make the details of extruding assembly unit of steel 5 that is strengthened by nitrohardening.Документ Contact problem of elastic strips with initial stresses with periodically placed resilient protective strap(Хмельницький національний університет, 2019) Dikhtyaruk, N.N.; Kurinienko, O.V.; Poplavskaya, E.A.; Діхтярук, М.М.; Курінєнко, О.В.; Поплавська, О.А.The present article considers the formulation and solution of the problem on contact interaction of a pre-stressed band with regularly placed elastic cover plates. The study has been carried out within the framework of the linearized elasticity theory in general form for the theory of large (finite) initial deformations and two variants of the theory of small initial deformations with an arbitrary structure of the elastic potential [1]. The solution of the problem comes down to a singular integro- differential equation for unknown contact stresses with a kernel expressed in the form of a sum of the kernel and some regular kernel under certain boundary conditions. The solution sought is given in the form of a series of Jacobi polynomials. A quasiregular infinite system of linear equations is obtained in order to determine the unknown coefficients of the series [2].Документ Direct wear-contact task for radial sliding bearing(Хмельницький національний університет, 2019) Dykha, O.V.; Babak, O.P.; Dytynyuk, V.O.; Дыха, А.В.; Бабак, О.П.; Дытынюк, В.А.The paper presents an approximate solution of the wear-contact problem for a cylindrical sliding bearing. The law of wear is adopted in a dimensionless form, depending on the determining factors: contact pressure and sliding speed. The law of wear also includes: the coefficient of friction, the modulus of elasticity of the material of the bearing, the gap in the bearing and the thermal diffusivity of the material of the bearing. For the calculation, an approximate relationship was used for maximum contact pressures in the bearing. To simplify the geometric dependence of normal wear on the contact angle, the decomposition of trigonometric functions into a power series was used.Документ Investigation of the influence of thickeners and fillers on Properties of lubricants obtained by recycling technologies(Хмельницький національний університет, 2019) Mandzyuk, І.А.; Prysiazhna, К.О.; Мандзюк, І.А.; Присяжна, К.О.The possibility of obtaining a new class of the bases of lubricants by modifying the natural fat molecule by a fragment of a link of synthetic polymer - polyethylene terephthalate is considered. The influence of thickeners of various chemical nature is considered: paraffin P400, beeswax, aerosil 200, modified bentonite, sodium stearate and lithium stearate on antifriction characteristics of PET-acylglycerol based on beef fat. The influence of fillers, namely: aerosil 200, modified with quaternary ammonium salts bentonite clay (particle size is 20 nm), talc, graphite and molybdenum disulphide on the value of static shear stress and anti-wear properties are considered.Документ Cavitation and erosion wear resistance of carbon structural steels(Хмельницький національний університет, 2019) Skyba, M.Ye.; Oleksandrenko, V.P.; Stechyshyn, M.S.; Martynyuk, A.V.; Скиба, М.Є.; Олександренко, В.П.; Стечишин, М.С.; Мартинюк, А.В.In the paper, based on the analysis of literary sources and own researches of authors, the results of cavitation and erosion wear resistance of structural steels are systematized depending on their thermal processing (structure) and type of environment. The structural structure of steels is based on the analysis of wear resistance during cavitation and erosion fracture of surfaces, and the mechanisms of cavitation fracture of dodectoid, zavectotoid and perlite steels are considered. Destruction of dodectoid steels begins with ferrite, and then extends to perlite grains. The wear resistance of the pearlite grains of the plate-shaped form is higher than that of perlite of the granular form. Cavitation wear resistance of zeutectoid steels is determined mainly by the properties of perlite. The mechanical properties of which depend on the dispersion and shape of the particles of cementite. In perlite steels, reducing the size of its grain increases their erosion resistance, especially in the presence of cementite in the structure of the grid, and not ferrite grids. Using different types of thermal and thermocyclic heat treatment, it is possible to form appropriate structures and, accordingly, increase the cavitation and erosion wear resistance.Документ Equilibration of sugar centrifuges by method of automatic balancing(Хмельницький національний університет, 2019) Tkachuk, V.P.; Sokolan, K.S.; Sokolan, J.S.; Ткачук, В.П.; Соколан, Л.С.; Соколан, Ю.С.The article represents materials that illustrate operation principle of centrifuges for separation of massecuite strike on sugar refineries and methods of increasing reliability and performance quality of their operation are revealed in the article. Reasons of origin of centrifuge vibrations as a result of non-equilibrium during their operation are envisaged among other factors. Methods of vibration decreasing as a result of applying auto-balancing devices are offered and results of experimental researches on research stand are summarized.Документ Contact interaction of elastic strips with initial stresses with a infinite and finite stringers(Хмельницький національний університет, 2019) Dikhtyaruk, N.N.; Poplavskaya, E.A.; Kurinyenko, O.V.; Діхтярук, М.М.; Поплавська, О.А.; Курінєнко, О.В.The present article the problems of the contact interaction of infinite and finite elastic stringer with a prestressed elastic strip. The study is performed in the framework of the linearezed theory of elasticity in common form for the theory of large (finite) initial deformations and two variants of the theory of small initial deformations with elastic potential of arbitrary structure. Based on the assume that the stringers load at the same time the vertical and horizontal forces, fair model of bending beams in combination with horizontall elongation. This problem is mathematically formulated as a system of integrodifferential equations of a relatively unknown contact stresses. The system is solved in a closed forms using transformation of Fourier. Expressions of stresses are represented by Fourier integrals with a simple enough structure. Influence of initial stress on the distribution of contact stresses is study and discovered the mechanical effects under the influence of concentrated loads.Документ Estimation of the stress-strain state of a discrete medium by a plastic flow model(Хмельницький національний університет, 2019) Dorofeyev, O.A.; Kovtun, V.V.The article considers the possibility of using the apparatus of the plastic flow theory to evaluate the stress-strain state of a medium filled with discrete material. The ratio of the rheological model associated with the Coulomb condition is formulated, which takes into account the characteristic features of the deformation of discrete materials: the effect of dry coulomb friction and the manifestation of dilatation. The ratios which describe the boundary condition of the plastic medium, both under the conditions of Saint-Venant and Mohr – Coulomb, are given. In the solid-state plastic flow model, the Saint-Venant condition is used as a potential function. Therefore, it is logical to consider the use of the Mohr – Coulomb condition as a potential function in the plastic flow model of a bulk medium. This is done in the Drucker – Prager model. The authors analyzed the validity of the findings of this model with respect to the discrete environment. The ratio for the analysis of the reasons for the discrepancy between the conclusions of the Drucker – Prager model and the results of experiments with discrete materials is given. The comparison of the magnitude of the dilatation coefficient with the condition of coincidence of the stress and deformed state in the limiting stage of deformation of the discrete medium, suggests that the Drucker – Prager model which is associated with the Coulomb condition doubles the value of this coefficient. The ratio of the Drucker – Prager model is related to the stresses acting on non-orthogonal planes of the boundary equilibrium, with deformations along the orthogonal planes of maximum displacement. This leads to a discrepancy between the predicted model and the experimentally determined values of the dilatation coefficient, as well as the impossibility to reconcile the fields of the slip lines in the stress and deformation plane. The authors conclude that the highlighted differences between the theoretical conclusions and the results of experimental checks can be eliminated by presenting the relations of the model of the plastic flow of the discrete medium through the stresses and deformations that arise in the twisted conjugate sliding planes.Документ Research of the contact and deformation properties of lubricated surfaces(Хмельницький національний університет, 2019) Dykha, O.V.; Posonsky, S.F.The article considers the issues of contact interaction of steel surfaces under various contact conditions. To assess the depth of ball penetration, an experiment was conducted based on the indentation procedure on the Brinell press. The hypothesis of the formation of internal stresses under conditions of non-lubricated and contact in the presence of a lubricant is formulated. The effect of lubricant on the occurrence of resistance forces to the movement of the indenter in a special laboratory setup is investigated.Документ Analysis of the influence of nitriding in a glow discharge on the properties of a titanium alloy(Хмельницький національний університет, 2019-10) Машовець, Наталія; Mashovets, N.S.Ця робота присвячена результатам низькотемпературного азотування в тліючому розряді для розробки рекомендацій щодо подальшого практичного застосування. Модифікація поверхні титанових сплавів проводилася низькотемпературним азотуванням в тліючому розряді в без водневому середовищі. Основна перевага цього методу полягає у відсутності водневого окрихчування та повноцінного екологічного безпечного процесу. Застосування тліючого розряду дозволяє не тільки прискорити процес дифузійного насичення поверхні азотом, але й істотно змінить кінетику процесу та якість азотованого шару, зокрема його фізико-механічні властивості та фазовий склад.