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Analytical Determination of the Reduced Rotational Resistance Coefficient of the Construction Machine Slewing Gear
(Дніпровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2019) Bondarenko, Leonid N.; Posmitiukha, Oleksandr P.; Hlavatskyi, Kazymyr Ts.
EN: Purpose. Designing new models of construction machines is closely related to the development of slewing gear, and that, in turn, has a drive whose power and dimensions depend on the rotational resistance and the reduced fric-tion coefficient in the units. The absence of analytical dependencies for determining the reduced coefficient of friction for the rotation of construction machines, first, restricts the designer's ability to select materials, and secondly, does not allow the adoption of optimal design solutions. Therefore, the purpose of the article is to find analytical solutions to determine the rotational resistance in the slewing gear of construction machines, which allows project-ing more advanced gears and machines in general. Existing techniques are based on empirical dependencies and experimental coefficients that reduce the accuracy of calculations, increase the size and cost of work. It is proposed to improve the accuracy and simplify the process of determining the rotational resistance and the magnitude of the reduced rotational resistance coefficient of the building tower cranes. Methodology. The set objectives can be achieved by means of analytical dependencies for determination of rolling friction coefficients over linear and point contacts. This will enable to find the more accurate value of the resistance coefficient, and the constructor during the calculations to take targeted measures to reduce it, using the mechanical constants of materials of the units and their geometric parameters. The calculation is based on Hertz contact deformation theory and the body point plane mo-tion theory. Findings. The obtained dependencies will allow analytically to find the resistance of rolling resistance of rollers in construction machines with fixed and rotating pillars, with circular rotary devices, as well as in ball and roller slewing rings. The calculated values of the rotational resistance coefficients for some types of mechanisms give similar values with those recommended, while for others they significantly differ and require their refinement in reference values. Originality of the work consists in the use of analytical dependences for determining the reduced coefficient of the rotational resistance over linear and point contacts using Hertz contact deformation theory and Tabor partial analytic dependencies theory. Practical value. The obtained dependencies will allow to design new types of slewing gear units of the construction machines and to reveal the additional rotational resistances.
Analytical Method of Determining the Movement Resistance of a Tip for Forming Rectangular Technological Hole in the Lower Structure Tracks
(IOP Publishing, 2020) Posmitiukha, Oleksandr P.; Hlavatskyi, Kazymyr Ts.; Kravets, Svyatoslav V.; Suponyev, Volodymyr; Koval, Andrey
EN: Abstract. The aim of this work is to theoretically determine the total resistance to soil pricking with a wedge-shaped tip to create a rectangular cavity and to determine the influence of the size of the working equipment and soil environment in the repair of earthenware or areas where trench technology can-not be used. To determine the forces of the recess of the replaceable pilot, the law of change of soil pressure on the working surfaces of the working equipment was first determined, which is based on the idea of the change of the soil elastic state at its compaction was determined, which is determined by the compression module of deformation of the soil. The processes occurring during the formation of wells and new approaches to the improvement of calculations have been described. On the basis of the pro-posed model of the piercing process, the laws of change of the normal pressure of soil resistance on the surface of the wedge working equipment are established. Based on its value, the results of theoretical studies have received a rational form and parameters of the tip of the work equipment.
The Calculation of Stress Intensity Factor Steel of Railway Wheels
(Silesian University of Technology, Katowice, Poland, 2020) Vakulenko, Ihor O.; Proydak, Svetlana V.; Askerov, Hangardas
EN: From an analysis of the dependence complex of carbon steel properties on structural parameters, it was found that for an isostructural state, the influence of austenite grain size on impact strength exceeds the dependence on carbon content. As a result of explaining correlation relationships between individual mechanical characteristics, to evaluate critical stress intensity factor, a relationship is proposed based on the use of impact strength. The proportionality coefficient in proposed dependence is determined by ratio of elongation to narrowing at tensile test.
Concept of Determining the Friction Stir Welding Mode
(Національний гірничий університет, Дніпро, 2018) Vakulenko, Ihor O.; Plitchenko, Serhii; Murashova, Nataliia H.; Bohomaz, Volodymyr M.
ENG: Purpose. To determine the optimal mode of friction stir welding of aluminum alloy. Methodology. 2.5 mm thick plates made of aluminum alloy AMg5 with chemical content of alloying elements within grade composition were used as a material for the research. Friction stir welding was carried out using specially designed equipment with a preselected form and dimensions of working tool. At different ratios of the working tool rotation frequency the forces of pressing and speed of its movement along the connecting edges determined the metal heating degree and the quality of welded joint formation. Temperature of the connecting edges heating was determined by thermocouples immersed in metal at different distances from the welded joint. Rotational speed of the working tool was from 800 to 1600 min-1 with the effort of pressing to the plate surface from 580 to 1370 N and the speed of movement along the joint of 50 mm/min. Findings. On the basis of different ratios of the working tool rotation speed and pressing to the connecting edges, there were determined conditions for achieving the effect of constant softening during friction stir welding. In order to achieve a high level of welding joint quality during friction stir welding it is necessary to carry out the process at high revolutions of the working tool and low levels of pressing to the connecting edges. Originality. At the constant speed of the working tool rotation proportional increase in alloy temperature from increasing the level of its pressing to the connecting edges is disturbed by achievement of conditions of the dynamic softening processes development. Practical value. The concept of choosing the technological parameters of welding process is determined, when it is preferred to increase in speed of the working tool rotation when the level of its pressing to the connecting edges decreases.
Determination Activation Energy of Friction Stir Welding
(WRTYS, Kyiv, 2017) Vakulenko, Ihor O.; Plitchenko, Serhii
EN: According to the technology of friction stir welding (FSW) heating of the edges is equal to 0.85-0.9 from the melting temperature of metal (T). Increase in temperature is accompanied by increased degree of the metal stirring, which leads to ambiguous influence on the metal density and concentration of cavities at different distances from the welding joint. At the same time, the temperature gradient across the section of joint leads to a different speed of recrystallization processes development and forming of structural heterogeneity in metal edges. Thus, the relevant question is to determine the optimal scheme of metal edges heating during the implementation of FSW technology. Material for the study was alloy AMg5. For different ratio of rotation speed and pressure on operating tool there were obtained the conditions of superplastic state of alloy at the temperatures of heating at the level of 0.45-0.5 from T, which corresponds to the beginning of dynamic recrystallization development during FSW. At the same time, it was evaluated the energy of activation (EA) of FSW process. Using the analysis of the obtained results it was determined the fact that when reaching the same temperature of alloy heating the EA value of FSW process decreases with increasing the rotation frequency of the operating tool and decreasing the degree of its pressing to the edges of welding joint. On the basis of the above mentioned the development of FSW technology should be directed toward the use of high speed rotations of the operating tool and low levels of its pressing to the alloy edges.
Determination of Equivalent and Optimal Sizes of Wedge Tip from Flange for the Static Perforation of Soil
(Український державний університет залізничного транспорту, Харків, 2018) Posmitiukha, Oleksandr P.; Kravets, Svyatoslav V.; Suponyev, Volodymyr; Glavatsky, Kazimir Ts.
EN: Abstract. The purpose of the study is to create a new design of the working tip for the perforation of the soil when laying two or more buildings trenchless way and determine its rational parameters. Method. It is known that for static perforation in the formation of cavities in the soil for communication is traditionally used cone-shaped working elements, which is the most common, cheap and reliable. However, the study revealed inefficiency. The design of the working elements of the soil perforation for trenchless laying of two or more buildings simultaneously in the form of a tip, which consists of a wedge-shaped part and a control part in the form of a rectangle with half-cylinders. The basic principles and mathematical dependences of determining the size of the working body are described. Scientific novelty. Regularities of changes in soil pressure on the lateral, conical and wedge surface, flat and cylindrical part of the tip, allowed to obtain an analytical dependence for the calculation of the resistance force depending on the physical and mechanical properties of the soil, the diameter and the number of cases established simultaneously. Also, when comparing the cone-cylindrical and flat tips, it can be argued that the breakdown force of the flat tip decreases from 1.2 to 1.7 times.
Determination of the Causes of Rolling Surface Damage during Operation of the Railway Wheels
(Dnipro University of Technology, Dnipro, 2025) Vakulenko, Ihor O.; Plitchenko, Serhii O.; Yilmaz, A. F.
ENG: Purpose. Substantiation of the mechanism of damage formation on the rolling surface of railway wheels by different strength levels to determine optimal structural state of the carbon steel. Methodology. The material for study was steel from rim fragments of the railway wheels with a carbon concentration of 0.61 and 0.69 % and other chemical elements within the range of the grade composition. Samples for mechanical tests were subjected to thermal hardening to obtain different structural states. The microstructure was examined under light and electron microscopes, using quantitative metallography techniques. Metal wear was determined under dry friction conditions, with different degrees of slippage, on a machine of the SMC-2 type. Hardness was estimated by the Rockwell method, and micro hardness of structural components – on a PMT-3 micro hardness tester. Findings. Based on the analysis of the wheel-rail interaction, it was determined that resulting inhomogeneity at distribution of plastic deformation and heating temperature in the plane of the contact surface are due to the development of slippage processes. Heating the metal to temperatures higher than onset of phase transformations and subsequent accelerated cooling determine the mechanism of structural transformations. The difference between adjacent sections of the rolling surface with different structural states and corresponding level of strength determines conditions for the formation of a fracture center of the railway wheel during operation. Originality. Heating the metal to temperatures above onset of phase transformations from the wheel sliding along rail and subsequent forced cooling is the cause of formation of gradient of the structures from pearlite to martensitic-bainite. The cyclic nature of the change in the structural state of the metal from simultaneous influence elevated temperatures, high plastic deformations and phase transformations corresponds to the development of low-cycle fatigue processes. Plastic deformation of the rolling surface area with martensitic or bainite structures is accompanied by softening, and with pearlite structures – by a hardening process. Practical value. The obtained results of the development of phase transformations in carbon steel on rolling surface will be useful in determining optimal structural state of the railway wheels of different strength levels.
Determination of the Size of Theseal Zone and the Soil Pressure on Underground Communications in the Process of Soil Deformation by the Wedge-Shaped Tip
(НВП ПП «Технологічний Центр», Полтавська державна аграрна академія, 2018) Posmituha, Alexander; Kravets, Svyatoslav; Suponyev, Vladimir; Kulazhenko, Yevhenii Yu.
EN: The object of the study is a working element with a wedge tip for static perforation of the soil with the laying of several cases for underground utilities. One of the problems that require research is the laying, location and proximity of various types of underground utilities, laid trenchless way. The study of the zone of influence of working bodies on the ground and communication will give us the opportunity to more efficiently design the use of underground space, to reduce the risks of damage to or destruction of communications and reduce the cost of the work. Studies are based on the law of conservation of mass before and after compaction of the soil with a wedge tip and on the basic theories of soil mechanics. This allows you to determine the pressure of the soil on the working element and on the communication, located nearby. The result obtained in the work shows that the pressure value is not the same in different directions of the wedge working element. It is also proved that the number of cases, which are simultaneously laid, have little effect on the zone of elastic-plastic deformation of the soil. These effects make this form of hole indispensable when you need to simultaneously lay several, more than 3, cases, compared to the traditional conical-cylindrical tip. To determine the soil pressure on underground utilities were used only the size of the working elements, and data that are easy to determine – the type and density of soil, humidity, porosity and other standardized characteristics. The use of this method has a significant advantage over other methods, which are based on empirical relationships that are either difficult to determine or their reliability is questionable. Due to the reduction of the cross-sectional area of the deformable soil, the wedge working body is indispensable for stretching the group of cases.
Dynamics of the Interbank Exchange using Neural Technologies
(Scientific Publishing Center “Sci-conf.com.ua”, Lviv, Ukraine, 2022) Volkova, Svetlana A.; Anofriev, Pavlo G.; Hiliavskyi, Denys
ENG: Artificial intelligence is used to predict various events. Recently, the direction of predicting the exchange rate of bitcoin in pair with the dollar has been actively developing. Due to volatility, it is very difficult to predict the price of cryptocurrency. Recurrent neural network are proposed in the work.
The Effect of Stress Pulses on the Cyclic Endurance of Steel Axle Wheel-Set
(Nevsehir Haci Bektas Veli University, Cappadocia, Nevsehir, Turkey, 2019) Vakulenko, Ihor A.; Bülent, Kurt; Raksha, Serhii V.; Askerov, Hangardas; Hryshchenko, Mykola A.
ENG: For different temperature and speed deformation conditions, the nature of the increase in the number of defects in the crystal structure and the achieved complex of properties are due to the peculiarities of the internal structure of the metallic material. Compared with unidirectional static loading, the violation of the monotonous nature of the effective stress is accompanied by qualitative changes in the internal structure of metals and alloys. Thus, the pulsating nature of the acting stresses in case of fatigue, depending on the degree of cyclic overload per cycle, can lead to significant changes in the development of the processes accumulation and redistribution of defects in the crystal structure and, above all, dislocations. Based on this, the rate of accumulation of dislocations per loading cycle can be considered as one factor that will allow the development of measures to increase the cyclic endurance of metallic materials during fatigue. Compared to thermal technologies, treatments that are based on the use of short stresses pulses for moving defects in a crystal structure have gained some fame. In addition to sufficiently strong magnetic fields or high-power pulses of electric current, treatments based on mechanical effects on the metal can be used.
Energy-Efficient Excavation of the Soil of the Lower Track Structure by Bulldozers with a Combined Knife System
(IOP Publishing, 2020) Hlavatskyi, Kazymyr Ts.; Raksha, Serhii V.; Gorbenko, Yu. О.
ENG: The motivation of the research and further development of the new type combined knife system on the irreversible bulldozer blade and the results of the first series of laboratory studies of the process of digging the soil with the irreversible blade of the bulldozer with the first set of its physical models, which indicate the feasibility of continuing research in this direction. The proposed combined knife system makes it possible to realize oblique digging of the soil on the irreversible blade of the bulldozer and maximally complete its orientation in the prism of the soil before the blade in order to increase the productivity of the bulldozer with irreversible blade by reducing soil losses in the side rollers, reducing the time of filling and digging the soil by reducing the coefficient of specific soil resistance to digging. The paper substantiates the technology of more efficient use of bulldozers with non-return blade compared to their traditional counterparts, which is possible due to the use of the new combined knife system, and argues in favor of expanding the technological capabilities of the bulldozer with non-return blade, equipped with the proposed solutions new type with different digging angles and a spatial inclination of the cutting edges.
Energy-Efficient Means of Transporting Oil Products to Ukraine During Martial Law
(MATEC, 2024) Zelenko, Yuliia V.; Cherkudinov, Volodymyr E.
ENG: Carrying out transportation of oil products, there is a danger of having a negative impact on the environment - a leak of liquid can create an environmental problem for a certain area. Transportation of oil-containing cargoes to Ukraine, during martial law, is carried out by multimodal transport, namely, road, sea and rail modes of transport. As of June 2023, there are 14 border railway stations connecting Ukraine with five countries: Poland, Slovakia, Hungary, Romania and Moldova. International railway transshipment stations were studied, which allow oil products to be transshipped into tankers for further customs clearance and transportation to warehouses, civilian or military recipients. The distance of the transportation path is not always decisive in the matter of energy saving. Environmental friendliness and energy consumption during the transportation of petroleum products are also affected by the topography of the road, the landscape of the area where the roads pass, and the traffic on the roads with other vehicles.
Evaluation of the Influence of Dispersion of Pearlite on the Fatigue of Carbon Steel
(Springer Link, 2020) Askerov, Khangardas; Vakulenko, Ihor O.
EN: It is shown that the slope of a tangent to the fatigue curve can be used to analyze the effect of dispersion of pearlite on the fatigue strength of carbon steel. For a constant thickness of the ferrite-pearlite layer, we established an inversely proportional relationship between the indicated parameter and the density of accumulated dislocations. We also estimated the mechanism of influence of the dispersion of pearlite on the transition from low- to high-cycle fatigue of carbon steel.
Experimental Research of Ropeway Dynamics
(Kaunas University of Technology, Kaunas, Lithuania, 2022) Kuropiatnyk, Oleksii S.; Raksha, Serhii V.; Krasnoshchok, Oleksandr L.
ENG: Research of ropeways is carried out in several directions, one of which is the establishment of dynamic characteristics of rope systems under different operating conditions. In previous works, we proposed a mathematical model for calculating the frequency spectrum of ropeway, which is based on the representation of the ropeway traction circuit as a discrete-continuous dynamic system. The main purpose of the experimental studies is to confirm the adequacy of this model; its results are presented in this article. The considered single-span ropeway is usually used as a means of industrial transport for moving goods between production and storage facilities, in the mining industry – for transporting various materials from the place of extraction to railways and highways. Studies were carried out using experimental equipment developed by us. According to the results of the experiment, we drew the frequency diagrams, which show the change of eigenfrequencies of the ropeway traction circuit during the cars movement between stations. The total array of results includes information on the decoding of about a thousand oscillograms, which were obtained and studied according to the methodology developed by us.
Formation of Carbon Steel Structure During Hot Plastic Deformation
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, Dnipro, 2020) Vakulenko, Ihor O.; Bolotova, Daria M.; Proidak, Svitlana V.; Askerov, Hangardas; Cug, H.; Tchaikovska, H. O.
EN: Purpose. The main purpose of the work is to determine the peculiarities of the development of recrystallization processes of carbon steel austenite depending on the degree of hot plastic deformation and to develop proposals for improving the structural state of the metal of the railway solid-rolled wheel. Methodology. Two carbon steels of a railway wheel with a minimum and maximum carbon content of 0.55 and 0.65 % and other chemical elements within the grade composition of the steel 60 were used as research material. Samples in the form of cylinders with a diameter of 20 mm and a height of 40 mm were heated in a muffle furnace, exposed for a certain time to equalize the temperature across the cross section of the sample. After that, the samples were subjected to hot compression on Instron type test machine. The temperature interval of hot compression of the samples was 950–1100 ºС, with deformation degrees in height in the range of 10–40%. The strain rate was 10-3–10-2 sec-1 . A standard etching was used to detect the boundaries of the austenite grains. Structural studies were performed using Epikvant type light microscope at magnifications sufficient to determine the structure of austenite grains. The grain size of austenite was determined by the methods of quantitative metallography. Findings. In the case of hot compression of the railway wheel blank, increasing the concentration of carbon atoms only within the grade composition of the steel is sufficient to increase the average austenite grain size, which confirms the proposals to limit the carbon content in the metal of railway wheels. The formation of a certain degree of austenite structural heterogeneity at the cross section of the rim or hub of the railway wheel is due to a change in the development mechanism of recrystallization processes depending on the deformation value. Under conditions of the same degree of hot plastic deformation, the replacement of one-time compression by fractional one is accompanied by a violation of the conditions of formation of the recrystallization nucleus. As a result of the specified replacement of the scheme of hot plastic deformation we obtain reduction in the austenite grain size. Originality. Based on a study of the development of collective recrystallization processes during the hot compression of carbon steel of the railway wheel, it was determined that the increase in carbon content contributes to the austenite grain increase. After hot compression of the wheel blank, the structural inhomogeneity of austenite that occurs is determined by a change in the mechanism of recrystallization processes development. During deformations above the critical degree, the recrystallization nuclei are formed and successively grow, which leads to the structure refinement. In the case of deformations below the critical value, the growth of austenite grains occurs according to the coalescence mechanism, according to which fragments of boundaries with large disorientation angles consistently disappear. Practical value. For austenite grain refining in massive elements of solid-rolled railway wheel we offer to replace one-time hot compression by fractional one.
Frequency Analysis of Vehicle Drive with Cable Traction
(Український державний університет залізничного транспорту, Харків, 2018) Raksha, Serhii V.; Kuropiatnyk, Oleksii S.; Anofriev, Pavlo G.; Onopreychuk, Dmytro V.; Kovalov, Ihor
ENG: Abstract. The paper outlines the basic principles of constructing frequency diagrams and specifies the features of their application for the analysis of the dynamic state of the vehicle drive with cable traction on the example of a ropeway. To draw up the frequency diagrams, the ropeway traction circuit was presented as a dynamic system containing lumped masses and elements with distributed parameters. In this case, the moments of inertia of the rotating masses of the drive were brought to the traction pulley as a lumped mass. The traction cable segments are represented as elements with distributed parameters. The mathematical model describing the dynamic state of the drive consists of equations in the form of deformations of the traction cable segments using the positions of wave mechanics. Studies have shown that in most cases there is a fairly wide inter-resonance band, limited by the first and second eigenfrequencies. This phenomenon may be the basis for justifying the rational values of the rotational speed of the pulley as one of the kinematic parameters of the ropeway drive.
Improving the Performance Parameters of Railway Wheels with the Help of Optimal Design Technologies of their Electric Pulse Processing
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Vakulenko, Igor A.; Kuzin, Nickolai O.; Vakulenko, Leonid I.; Raksha, Sergey V.; Proidak, Svetlana V.
ENG: Abstract. The processing by pulses of electric current (PEC) of a fragment of the rim of a railway wheel was carried out on the DS10D equipment. When the density of the electric current is from 3 to 17 A/mm2, the processing cycle consisted of the action of a pulse with a duration of 2.5-3 s and a pause between pulses of 4 s. After 150 cycles of PEC, the hardness of cold-formed metal was reduced from 10 to 20%. Studies of the parameters of the metal structure of the wheels have determined that the processing of PEC leads to a decrease in the number of defects in the internal structure, which are accumulated as a result of cold deformation of the rim along the rolling surface of the railway wheel. It has been established that, according to the nature of the influence on the hardness distribution of carbon steel, the PEC treatment corresponds to changes during tempering in the average temperature range and allows to significantly increase the operating parameters of the wheels of railway equipment.
Influence Factors on Electrophysical Parameters of Composite Varistors
(Український державний університет науки і технологій, м. Дніпро, 2023) Ahadzade, Shafag; Vakulenko, Igor A.; Asgarov, Hangardash
ENG: Purpose. The work is aimed to evaluate the influence of the structural state of polymer phase on the response voltage and nonlinearity coefficient of a multilayer varistor based on zinc oxide. Methodology. Zinc oxide consisted of 97% zinc oxide and 3% total oxides of Bi2O3, Co3O4, MnO2, B2O3, SbO3, ZrO2, Al2O3. To obtain the composite of thermoplastic polymers and zinc oxide, non-polar and polar polymers, high pressure polyethylene and polyvinyli-denefluoride were used. The composites were obtained by hot pressing at the melting temperature of the polymer phase and a pressure of 15 MPa. After that, using silver paste measuring electrodes 10 mm in diameter were applied to the surface of the synthesized samples and then current–voltage characteristics were measured. Modification of composites under the action of gas-discharge plasma was carried out in a special cell that creates a dielectric-gas-composite system. The composites structure was studied by X-ray diffraction analysis and IR spectroscopy. Findings. The obtained experimental results show that the size of inorganic phase particles significantly affects the cur-rent-voltage characteristics of the composite varistor: at a given thickness of the composite varistor, the operation voltage decreases markedly, and the nonlinearity coefficient increases. The influence of electric discharge plasma on the polymer zinc oxide-composite results in a significant change in the permittivity and the concentration of local levels at the separation boundary of the composite. The results research showed that electrical plasma effect on the response voltage depends on the polarity of polymer matrices. Moreover, plasma processing itself significantly changes the structure of the polymer phase in the composite. Originality. The magnitude of the potential barrier at the phase boundary is mainly determined by the volume fraction and size of the main structural element of ZnO ceramics. The change in the structural state of the polymer matrix allows adjusting the response voltage and nonlinearity coefficient of volt-ampere characteristic of the multilayer varistor. Practical value. The discovered development of electron-ion processes in the polymer phase of the varistor indicates the need of taking into account the change in its service characteristics from the duration and intensity of use. The result obtained shows not only the reason for the properties change, but also the need to develop the measures to increase the service life of varistor.
Influence Ferrite Grain Size on the Development of Discontinuons Flow at Lowcarbon Steel
(Nevsehir University, Turkey, 2021) Vakulenko, Igor A.; Kurt, Bulent; Erdogdu, Ahmet Emrah; Asgarov, Khangardash
ENG: On example of low-carbon steel, it is shown that development of strain hardening processes, starting from the moment initiation of plastic deformation, determines nature behavior of the metal at all subsequent stages of loading. The conditions formation of deformation bands and reasons for the disappearance of intermittent yield section on the deformation curves are considered. The use of the dependence characteristics of strain hardening on the size ferrite grain made it possible to explain evolution structure of low-carbon steel at region of intermittent flow.
Influence of Current Shunting and Technological Parameters of Spot Welding on the Strength of Joints of Dimensional Products
(Dniprovsky State Technical University, Kamianske, 2024) Nosov, Denys; Peremitko, Valerii; Plitchenko, Serhii O.; Makarenko, Mykola; Shevtsov, Viktor
ENG: The effect of current shunting and technological parameters of spot welding on the strength of joints of dimensional products was studied. Experiments were carried out using a spot contact welding machine type MT-1614. As the main material to be joined, structural carbon steel of the 08Yu brand was chosen in the form of plates of various thicknesses. After welding, samples were made for testing according to standard techniques for shearing, tearing, or twisting. The experimental part of the study included determining the dependence of the fracture force and weld nugget diameter on the welding current, the distance between welded spots, and the duration of the welding current pulse. It was determined that the optimal welding current to ensure high strength of welded points is 7400…8000 A. Exceeding this value leads to a decrease in strength, especially when the distance between welded spots increases. The duration of the welding current pulse also plays a significant role: the optimal increase in strength is observed with pulses lasting 0.18…0.22 s. for currents of 7900…8200 A. The dependence of the diameter of the welded spot on the distance between the welded spots and the duration of the pulse was also established. A significant increase in the distance between the welded points leads to a decrease in their diameter. On the other hand, the duration of the current pulse in the range of 0.22...0.24 s increases the diameter of the points to 22 % on average. Based on the results of the experiments, mathematical models were developed that quantitatively evaluate the influence of the investigated parameters on the strength and diameter of the welded spot. Practical recommendations include optimizing welding parameters and implementing mathematical models in the production process to predict the quality of welded joints. The obtained results will contribute to improving the quality of welded joints and the efficiency of production processes in the manufacture of large-scale products.
Influence of Grain Size Ferrite on Speed of Distribution Sonic Vibrations in Alloy Steel
(China, 2016) Vakulenko, Ihor O.; Nadezhdin, Yurii L.; Sokyrko, V. A.; Yaremchuk, A.
ENG: On the example of steel XI8TI after cold rolling and annealing influence of grain size ferrite and texture is investigational on speed of distribution sonic vibrations. Character influence of grain size and texture is set on correlation of hardness and speed of distribution sonic vibrations.
The Influence of Nonmetallic Inclusion on Strain Hardening Carbon Steel
(Silesian University of Technology, Katowice, Poland, 2019) Vakulenko, Igor A.; Vakulenko, Leonid I.; Proydak, Svetlana V.
EN: Summary. On a fragment of the rim of a railway wheel removed from service, the volume of the metal with non-metallic inclusions located near the tread surface was investigated. The use of the microhardness measurement technique made it possible to establish the nature of strain hardening of carbon steel near non-metallic inclusions. It showed that with a normal orientation of the plastic flow relative to the inclusion surface, the metal volumes undergo hardening. In proportion to the appearance of a fraction of the tangential component of the deformation near the nonmetallic inclusion, a decrease in the degree of hardening of the metal was observed.
Influence of Perlite Dispersion of Carbon Steel on the Fatugue Processes
(Springer, 2018) Vakulenko, Ihor O.; Kawalek, Anna; Vakulenko, Leonid I.; Proidak, Svitlana V.
EN: Using the example of carbon steel with perlite structure it was determined the influence nature of the ferrite layer thickness of perlite on the angular coefficient of tangent at a certain point of the fatigue curve. Based on the analysis of the obtained dependencies, it is determined that the value of angular coefficient of the tangent can be used to evaluate the resource of limited endurance of the metal under conditions of cyclic loading.
Influence of Plastic Deformation Carbon Steel on the Process of Burning lectric ARC
(Silesian University of Technology, Poland, 2021) Vakulenko, Igor A.; Plitchenko, Sergey; Kurt, Bulent; Askerov, Hangardas; Proydak, Svetlana V.; Erdogdu, Ahmet Emrah
EN: During a study of the combustion process of a direct polarity electric arc, a directly proportional dependence of the electric current value on the degree of cold plastic deformation of carbon steel used as an electrode was found. To calculate the value of the electric current during arc burning, in the indicated ratio, it was proposed to replace the surface tension force of the liquid metal with the surface tension of ferrite of plastically deformed carbon steel. Calculation of the ferrite’s surface tension value on the deformation degree of the steel under study through the size of the coherent scattering regions was used to explain the observed dependence of the electric current during arc burning. From the analysis of the considered correlation ratios, it was found that with an increase in the cold deformation degree, the refinement of the coherent scattering regions results in the ferrite’s surface tension increase and consequently, to an increase in the electric current during arc burning. Comparative analysis of the obtained results of calculating the value of electric current during arc burning through the surface tension of ferrite of cold-deformed carbon steel showed a fairly good coincidence with experimental data. The differences did not exceed 9%.
Influence of Structural Parameters of Low-Carbon Steel on Electric Arc Burning
(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Vakulenko, Ihor O.; Plitchenko, Serhii; Murashova, Nataliia H.
EN: Purpose. The article is aimed to evaluate the influence of structural parameters of low-carbon steel on arcing process.Methodology. The values of the micro- and substructure characteristics of the electrode wire metal were changed by varying the parameters of heat treatment and cold deformation by drawing. The degree of plastic deformation was obtained by drawing blanks from different initial diameter to final dimension of 1 mm. The thermal treatment was carried out in electric chamber furnace of the SNOL-1,6.2,5.1/11-IZ type. The temperature was measured by chromel-alumel thermocouple and the electromotive force was determined using the DC potentiometer. In order to obtain the substructure of different dispersion degree the steel (after quenching from temperatures and tempering at 650°C for 1 hour) was subjected to cold drawing to reduction 17 – 80%. To form structure with different ferrite grain size the steel after drawing was annealed at 680°C for 1 hour. The microstructure was examined under a light and electron transmission microscope UEMV-100K at the accelerating voltage 100 kV. The grain and subgrain sizes were evaluated using the methodologies of quantitative metallography. A welding converter of the PSG-500 type was used to study the arc welding process of direct and reverse polarities. Findings. The experimentally detected value of the welding current, which depends on the degree of deformation during wire drawing, under conditions of stable arc burning of direct polarity is about an order of magnitude lower than the calculated value. Similar difference was found for the arc of reverse polarity: the experimental value of the welding current is 5...6 times less than the calculated value. Dependence analysis shows that, regardless of the polarity of the welding arc, a good enough agreement between the calculated and experimental values of the welding current is limited to deformations of 60%. For deformation degrees of more than 60%, the differences are explained by qualitative changes in the dislocation cell structure. Originality. In the conditions of stable arcing of different polarity for the electrode of low-carbon steel, an extreme dependence of welding current on the degree of cold plastic deformation was observed. Practical value. Influence of ferrite grain size of electrode wire on the value of welding current is much greater than that from substructure presence.
Influence of Substructure Strengthening of Law-Carbon Steel on the Arcing Process
(WRTYS, Kyiv, 2017) Vakulenko, Ihor A.; Plitchenko, Sergey; Nadezhdin, Yurii L.; Kirienko, Yu. D.
EN: For the arcs of forward and reverse polarities there found extreme dependences value of electric current on cold drawing with a maximum at 60% strain. In order to explain the nature of the dependencies of value of electric current on cold drawing the equation for estimating electric current was used with the replacement of surface tension coefficient for the surface tension coefficient of the ferrite of low-carbon steel. Taking into account the fact that as cold drawing increases from 17 to 80% the size of cells is reduced by 30%, the value surface tension coefficient of the ferrite was increased approximately by 1.5 times. After substituting surface tension coefficient of the ferrite in the ratio it has been found sufficiently good agreement of value of electric current with the experimental values of the welding current for reductions of up to 60%. Increase of cold drawing over 60% has led to an increase in differences up to 14 – 22% between value of electric current and the obtained experimental data.
Influence of the Isothermal Transformation Temperature on the Structure and Properties of Low-Carbon Steel
(Український державний університет науки і технологій, Дніпро, 2024) Vakulenko, Ihor O.; Plitchenko, Serhii O.; Asgarov, Khangardash; Lytvynov, Bohdan V.; Orak, Abdulkadir; Umur, Hakan
ENG: Purpose. The study is aimed at evaluating the effect of the isothermal transformation temperature on the structure and properties of low-carbon steel. Methodology. The material for the study was a 3 mm diameter wire made of mild steel with the following chemical composition: 0.21% C, 0.47% Mn, 1.2% Si, 0.1% Cr, 0.03% S, 0.012% P. The 0.3 m long wire samples were subjected to austenitizing at 920 °C for 8...9 min, after which they were held iso-thermally for 11 min at temperatures of 650...200 °C, followed by cooling in air. The strength, plastic properties, and strain hardening coefficient were determined from the analysis of tensile curves. Findings. It was found that a decrease in the temperature of isothermal transformation, starting from 450...400 °C, increases the amount of Widmannstätten ferrite due to the disappearance of polyhedral ferrite grains. At the same time, the number of areas with locally located dispersed cementite particles similar to pearlite colonies increases, and bainite crystals appear. Against the background of a sharp decrease in the strain hardening coefficient in the range of 450...400 °C, the ability of the bainite phase to undergo plastic deformation should be considered one of the reasons for the delay in den-sity reduction. Originality. The effect of steel hardening with a decrease in the pearlite transformation temperature is based on the grinding of ferrite grains, an increase in the amount of Widmannstätten ferrite, and the dispersion of pearlite colonies. The strengthening effect of steel with a bainite structure is based on an increase in the degree of supersaturation of the solid solution with carbon atoms and dispersion hardening by particles of the carbide phase. Practical value. The optimal structural state of steel intended for the manufacture of such critical elements as a sup-port beam, railroad car bogie, etc. is a mixture of phase components with different dispersion and morphology, and their quantitative ratio is determined by the operating conditions of a particular product.
Influence of the Shock Wave of Electric Discharge on the Fatigue Characteristics of Thermally Hardened Steel
(springer, 2018) Vakulenko, Ihor O.; Bolotova, Daria M.; Hryshchenko, Mykola A.
ENG: The procedure of treatment of thermally hardened steel by pulses of shock waves from electric discharges in water increases its hardness and the limited fatigue strength. As a result of the action of shockwave pulses, the number of dislocations increases. This guarantees the propagation of deformation in a cycle, which promotes the increase in cyclic fatigue strength.
Influence Structure on the Plasticity of Carbon Steel of the Railway Wheel Rim in Operation
(Silesian University of Technology, Poland, 2022) Vakulenko, Igor A.; Vakulenko, Leonid I.; Bolotova, Dariy M.; Kurt, Bulent; Asgarov, Hangardash; Çölova, Ömer
ENG: Summary. When simulating the operating conditions of the rim of a railway wheel, an analysis of change in the structural state from the possible degree of plastic deformation and the heating temperature of steel near the rolling surface was carried out. The development processes of spheroidization and coalescence of cementite during heating of the cold-worked steel change its ability to strain hardening. Substructure changes during heating to temperatures of 500-550°C deformed steel are accompanied by a simultaneous decrease in its ability to strain hardening and the level of plasticity. When heated above 500-550°C, the development of ferrite recrystallization processes provides a gradual transition of the metal from substructure hardening to hardening from grain boundaries with large angles of disorientation. It is shown that regardless of the nature of the main structural element, the ability of steel to strain hardening and the level of plasticity after heating are related by a proportional relationship.
Influense of the Shock Wave Treatment on Fatigue Carbon Steel
(Print ABC, Netanya, Israel, 2017) Vakulenko, Igor A.; Lisnyak, Alexander G.; Griaznova, Ludmila; Bolotova, Daria M.
EN: The process of introducing additional number of dislocations in the heat-hardened steel after shock wave pulse treatment apparently is not accompanied by the development of dislocation annihilation. Furthermore, implementation of the deformation per cycle for the area of high-cycle fatigue is ensured by the participation of more dislocations. Thus, in the process of shock wave pulse treatment, the vast number of introduced dislocations is mobile and able to interact with further cyclic loading or it takes place additional unlock of previously fixed dislocations after hardening and tempering. Overall, on the destruction surface after treatment with shock wave pulses it is found increased number of dislocations that are located in different crystallographic slip systems. They can be seen as evidence of the development of quite complex dislocation reactions that increases the metal limited endurance during cyclic loading.
Insights into Factors of Damage of Surface Rolling of Railway Wheels During Operation
(The Silesian University of Technology, 2019) Askerov, Hangardas; Vakulenko, Igor A.; Grischenko, Nikolaji
EN: The systematization results of microstructure studies of carbon steel has made it possible to explain the mechanism of formation of certain damages to the rolling surface of railway wheels during operation. The evaluation ability of metal to strain hardening was used to explain the nature of the influence compactly located non-deformable dispersed particles on the strength properties steel during cold plastic deformation. In the process of the interaction of a railway wheel with a rail, successively occurring heterogeneities in the distribution of the plastic flow metal are one of the main reasons for the formation of defects on the rolling surface of the wheel.
Investigation of the Influence of Elastic-Mass Characteristics of the Axle Test Stand Links on Its Own Oscillation Frequencies
(IOP Publishing Ltd, 2021) Raksha, Serhii V.; Anofriev, Pavlo G.; Kuropiatnyk, Oleksii S.; Plitchenko, Serhii
ENG: The reliability of work according to the criteria of vibration stability of the stand for testing the axles of wheelsets for endurance is largely determined by the natural vibration frequencies of the stand. The work considers a stand with a lever structure for loading the tested axles. In order to determine the influence of the parameters of the cross-section of the links on the natural frequencies of the vibration stand, the frequency characteristics were obtained by the method of mathematical modeling for two variants of the design schemes of the stand. Studies have shown that increasing the cross-sectional area of the levers without measuring other linear dimensions leads to a simultaneous increase in their mass and cruelty. The rigidity of the levers is defined as for beams on two supports with a load of a transverse concentrated force. As a result, the calculated values of the natural frequencies of the stand vibrations change insignificantly. A deeper analysis of the Eigen frequency characteristics of the stand with the tools of the Matlab system made it possible to obtain linear regression equations with the coefficients of determination close to one. The obtained research results gave reason to expect a decrease in stresses in the metal structures of the stand with an increase in the cross-sectional area of the levers, however, the values of the natural frequencies of the stand vibrations vary within a few percent. The way to control the natural frequencies of the stand vibrations only by changing the profile parameters is ineffective.
Justification of Criteria for Ropeways Energy Efficiency
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Raksha, Serhii V.; Kuropiatnyk, Oleksii S.; Krasnoshchok, Oleksandr L.
ENG: Purpose. The article is aimed to form and justify the energy efficiency indicators of ropeways of traditional design and ropeways with self-propelled wagons based on the determination and comparison of their values. The substantiation of the energy efficiency criteria of ropeway wagons allows us to determine fully the direction of further research in the field of development of alternative transport mode. Methodology. To obtain initial data, the authors reviewed the world trends in the development of ropeway wagons, proposed analytical formulas for determining criteria for ropeways` energy efficiency used to compare traditional ropeways and ropeways with self-propelled wagons. Herewith, we took into account the influence of the loading degree and rated power on the electric motor efficiency. In order to take into account the energy dissipation in the haul rope through its elastic properties, the concept of the efficiency coefficient of the haul rope was introduced. Findings. The authors formed a methodology for calculating the efficiency of ropeways, developed formulas for determining energy efficiency. We assessed the influence of the ropeway characteristics on their calculated values; constructed dependence graphs of the self-propelled ropeway efficiency coefficient on the rated electric motor power and the efficiency coefficient on the ropeway drive loading, as well as compared general efficiency coefficients for ropeways with self-propelled wagons and for ropeways of traditional design. The results are based on the averaged values of the electric motors parameters at their different loads. Originality. The authors first proposed and justified the energy-efficiency criteria for ropeways that make it possible a comparative analysis of traditional ropeways and those with self-propelled wagons. We determined the dependence of these indicators on the ropeway parameters. Practical value. The results of the comparative analysis of traditional construction of ropeways and the ropeways with self-propelled wagons, based on the proposed energy efficiency indicators, can be used to substantiate the feasibility of using certain type of rope-ways for the implementation of individual transport processes. The construction diagram of a self-propelled wagon can be used in the development of energy efficient passenger ropeway projects
Justification of Parameters of Wheelset Axle Fatigue Strength Test-Bench for Railway Rolling Stock
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Kuropiatnyk, Oleksii S.; Raksha, Serhii V.; Anofriev, Pavlo G.
ENG: Abstract. The operation safety of the railway rolling stock depends directly on the strength of the base part of the wheelset – its axle. Therefore, in recent years numerous studies of theoretical and experimental nature, both for means of rail transport, and for machines containing rail track equipment are carried out. This paper substantiates the main parameters of the fatigue test bench for axles for wheelsets of railway rolling stock. We performed an analysis of the load schema for bench tests, determined the dependence of the bench work force on the parameters of the wheelset axle. In addition, we substantiated the design and parameters of vibrator. For the research, we adopted the following criteria of rationality: work force, energy consumption and longitudinal dimension of the test bench. The design is considered the best, if these criteria acquire the smallest values. The results of the research indicate that the load scheme “cantilever beam” is rational for the fatigue bench tests of the axles for wheelsets of railway rolling stock. The best design of the vibrator have to provide the test bench work force by rotating the unbalanced mass around the stationary wheelset axle. The rational vibrator contains a sectoral eccentric mass rotating at an angular velocity of about 150 s-1. In this case, the eccentric mass value is about 80 kg, and its eccentricity is 135 mm.
Justification of the Parameters of the Life-Test Bench for Railway Wheelsets
(IOP Publishing Ltd, England, 2021) Raksha, Serhii V.; Anofriev, Pavlo G.; Kuropiatnyk, Oleksii S.
ENG: One of the tasks that need to be solved in order to predict the life of wheelsets is to assess the contact strength and wear of their parts. Thus, the purpose of this work is to develop a scheme and justification of the parameters of the life-test bench for railway wheelsets in conditions close to real operating ones. This bench simulates a contact of “wheel-rail” pair as a contact of “wheel-roller” pair. To ensure compliance of the bench tests conditions with the real wheelsets operation conditions we took that the maximum contact pressure in the “wheelroller” pair is equal to the maximum contact pressure in the “wheel-rail” pair. As results of this study we obtained the dependences of the values of the roller diameter and the working force of the bench on the characteristics of the tested wheelset and proved the mutual influence of these quantities. For railway wheelsets with an axle load of 230.5 kN and wheels with a tread diameter of 957 mm, we obtained the following values of the bench parameters: roller diameter is 75 mm; working force of the bench is 8,375 kN; wheel speed is 500 rpm; number of rollers is 8; test duration is about 220 h.
Mathematical and S-Models of Cargo Oscillations During Movement of Bridge Crane
(Національний гірничий університет, Дніпро, 2019) Raksha, Serhii V.; Anofriev, Pavlo G.; Bohomaz, Volodymyr M.; Kuropiatnyk, Oleksii S.
ENG: The effectiveness of research on the basis of mathematical models (linear, nonlinear) describing the dynamics of bridge cranes and cargo oscillations during transitional modes of movement, increases significantly with the use of numerical methods and simulation models created by visual programming tools.
Mathematical Modelling of Mixture Formation in the Combustion Chamber of a Diesel Engine
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Zhevzhyk, Oleksandr V.; Potapchuk, Iryna Yu.; Horiachkin, Vadym M.; Raksha, Serhii V.; Bosyi, Dmytro O.; Reznyk, Andrii
ENG: The object of research is the process of fuel mixture formation in a vortex combustion chamber located in the piston of a diesel engine. Ineffective mixture formation leads to increased specific fuel consumption and harmful emissions into the atmosphere. The research addresses determining the conditions under which complete evaporation of droplets is achieved and the required ratio of the amount of fuel vapor and the available amount of air depending on the piston radius. A mathematical model was created to describe the behavior of fuel droplets under the influence of aerodynamic forces, heat transfer, and phase transition processes. The calculations determined the radial fuel vapor concentration and air-fuel ratio distribution. The study found that fuel droplets with sizes ranging to 90.7 µm are completely evaporated which contributes to volumetric mixture formation. The model also identified regions where the mixture reaches stoichiometric conditions necessary for autoignition, particularly at a radius of r/Rc=0.22. This is explained by the rapid evaporation of small droplets, the number of which, as a function of the diameter distribution, is the majority, and their high speeds of movement relative to air and high mass transfer coefficients in the initial spraying area. The study demonstrates that despite non-uniform fuel vapor distribution, volumetric mixture formation is achieved. The interaction between fuel droplets and the swirling air motion ensures adequate mixing, facilitating complete and efficient fuel combustion. The results can be applied to optimize diesel engine designs by improving combustion chamber geometry and fuel injection strategies. The model is particularly useful for engines with high-pressure fuel injection systems. The work results contribute to developing more efficient diesel engines that comply with stricter emission regulations.
Modernization of Platform Schnabel Car with a Carrying Capacity of 220 Tons
(Дніпровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2021) Kebal, Ivan Yu.; Krasnoshchok, Oleksandr L.
ENG: Purpose. The article is aimed to calculate the strength of the element of the special design of the Schnabel car to increase the carrying capacity up to 250 tons, as well as consider the possibility of using special cars to transport the oversized cargo according to the strength calculation results of the span bolster of the Schnabel car. Methodology. A special design of the span bolster of the Schnabel car was developed, which allowed increasing the carrying capacity of the platform Schnabel car to 250 tons. SolidWorks CAD allowed testing the span bolster strength of the modernized Schnabel car. Findings. A review analysis of railway Schnabel cars has been performed. The possibility of testing the strength of the Schnabel car design details using modern SolidWorks CAD is considered. When loading the span bolster of the modernized Schnabel car with a compressive force of 2.5 MN, the stresses do not exceed the allowable, and the design has no weaknesses. The specialists of Design and Development Technolog-ical Bureau for the Design and Modernization of Rolling Stock, Track and Artificial Structures performed research and development for the production of a sixteen-axle platform Schnabel car with a capacity of up to 250 tons. Originality. The mathematical model of the modernized sixteen-axle platform Schnabel car with a loading capacity up to 250 t was further developed. The implementation of the mathematical model in SolidWorks CAD allowed testing the design for the strength of the Schnabel car. Practical value. The results of the work can be useful for the design departments for rolling stock design and relevant specialists. Modern CAD in some way simplifies the process of designing parts and assemblies of mechanisms, allowing one to test certain system parameters with high accuracy.
Optimisation of Petroleum Product Transportation by Multimodal Transport During Martial Law
(Springer Science and Business Media LLC, 2024) Zelenko, Yuliia V.; Cherkudinov, Volodymyr E.; Tarasov, Vsevolod; Soroka, Maksym
ENG: The hostilities in Ukraine have significantly changed the logistics of petroleum product supply. Overland routes via EU countries, in particular Poland, Romania and the Baltic states, have become the main transport solution. Rail transport remains the main mode of transportation for petroleum products, providing significant volumes, but faces the challenges of low capacity and delays at the borders. Road transport is showing growth due to the flexibility required in the crisis. The relevance of the work is determined by the need to increase the efficiency of logistics in the face of rising costs of transport resources and economic challenges that may be associated with a large number of both direct and indirect factors (economic, technological, political, security, etc.), the analytical set of which indicates the vulnerability of the security system for the transport of high-risk cargo.
The Optimum Design of Compressed Thin-Walled Columns of Open Cross-Section
(2000) Manevich, Arkadiy I.; Raksha, Serhii V.
ENG: The structural optimization problem for compressed thin-walled columns of open cross-section (channel and lipped channel) is considered on the base of the linear stability theory and the nonlinear interactive buckling theory. Optimal dimensionless parameters are presented as a function of a single leading parameter of load and geometry P* and imperfection amplitudes.