Ukrainian Journal of Mechanical Engineering and Materials Science. – 2015. – Vol. 1, No. 1

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Науковий журнал

Засновник і видавець Національний університет «Львівська політехніка». Виходить двічі на рік з 2015 року.

Ukrainian Journal of Mechanical Engineering and Materials Science = Український журнал із машинобудування і матеріалознавства : науковий журнал / Lviv Politechnic National University ; editor-in-chief Oleksiy Lanets. – Lviv, 2015. – Volume 1, number 1. – 134 p. : il. – Паралельна назва англійською.


Recent Submissions

Now showing 1 - 13 of 13
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    Innovation technologies in training specialists in engineering materials science
    (Publishing House of Lviv Polytechnic National University, 2015) Duriagina, Zoya; Bohun, Lidiya; Pleshakov, Eduard; Tepla, Tetiana
    The aim of educational program TEMPUS is the integration of Eastern countries in the Bologna process. Participating of Lviv Polytechnic National University in project “Modernization of two cycles (MA, BA) of competence-based curricula in Material Engineering according to the best experience of Bologna Process – 543994-TEMPUS-1-2013-1-BE-TEMPUS-JPCR” allows to improve the quality of training of specialists in the field of materials science. Directions of “MМATTENG” project realization by Applied Material Science and Materials Engineering chair, implementation of computer-integrated technologies within the project, formation of modernized educational programs, trainings and retrainings of lecturers, seminars on the base of EU Universities, enterprises and companies-developers of software products and formation of the common research centers of materials science with participation of leading foreign and home companies are described in this article.
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    Causes of ductility-dip cracks formation In In52 and In52 MSS alloys during fusion welding
    (Publishing House of Lviv Polytechnic National University, 2015) Beliaiev, Grigorii; Volosatov, Ivan; Kakhovskyi, Mykola
    The aim of the paper is to investigate one of the causes of ductility-dip cracks (DDC) formation. The main aim of this work is calculation of grain boundaries (GB) cohesive energy in nickel based In52 and In52 MSS alloys. For measuring the GB energy anisotropy methods of thermal etching and light interferometry were used. DDC form on the grain boundaries of nickel based alloys due to adsorption of impurities during multipass welding. The In52 alloy has tendency to form DDC during multipass welding fusion unlike In52 MSS one doped with Mo and Nb. The main cause is the change of thermodynamic state of the GB, as it is indicated by the decrease in the cohesive energy to 1.8-1.26 J/m2. During multipass fusion welding in In52 alloy adsorption of S and O from the grains body to GB takes place. The average concentration of O and S on the surface of DDC for high angle boundaries is within 2.3-4.5 and 0.5-1 at. %, respectively. Presented in this paper results have shown the influence of welding heat for reduce the cohesive strength of GB and, as a result, of the formation of DDC. Quantitative effect of S and O as embrittlement elements on the value of decrease in the cohesive energy was shown.
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    Micromechanical properties and thermal annealing of zinc oxide bulk ceramic
    (Publishing House of Lviv Polytechnic National University, 2015) Virt, Ihor; Pavlovskyy, Yuriy; Hadzaman, Ivan
    Zinc oxide has numerous commercial device applications. Polycrystalline ZnO varistors, for example, are widely used in high voltage and power-related applications in industries such as microelectronics. One of the ways to control the properties of ZnO is its annealing in various environments, including oxygen, which leads to increased hardness and fracture toughness of ceramics. Therefore, the study of micromechanical properties of materials for modern electronics is an important and vital issue, both in terms of technology for improving quality of the final product and from the point of view of prospect of its practical use. The structural properties of the ceramic samples of ZnO have been studied. The average grain size has been defined. The micromechanical properties have been studied. The temperature conditions of increasing microhardness of ZnO have been defined after annealing in an oxygen atmosphere.
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    Modification of surfaces of special alloys by nitrogen for power engineering
    (Publishing House of Lviv Polytechnic National University, 2015) Duriagina, Zoya; Tepla, Tetiana
    The use of nitrogen as an alloying element presents a great interest for the improvement of properties of alloyed steels and special alloys. Superficial layers were formed by ionic implantation and by melting the surface by nitrogen plasma. After this kind of treatment, there form a continuous defect-free layers with a good adhesion to the surface. Surface treatment of steels and vanadium alloys increases their corrosion resistance and microhardness of surface layers. A combined supply of alloying elements into the melting area allows us to control the type and the density of secondary phases which are formed as the result of the reaction diffusion. In this way, depending on external needs, it is possible to increase either corrosive-electrochemical properties of the surface (when alloyed layers consist mainly of nitride or oxinitride phases) or wear resistance (when carbide or carbonitride phases will constitute a greater specific volume in the formed layers).
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    The structure, mechanical and electrophysical properties of monocrystalline silicon under influence of constant magnetic field
    (Publishing House of Lviv Polytechnic National University, 2015) Kutzova, Valentina; Nosko, Olha; Sulay, Andrey
    The monocrystalline silicon is one of the most important materials in the view of the fact that it is used in contemporary electronics. The issues concerning silicon processing methods up to now attract a lot of attention of scientists all around the world. From this point of view, the influence of constant magnetic field upon the monocrystalline Czochralski silicon had been studied. The processing of monocrystalline Cz-Si (alloyed with Zr, Hf, Mg, Al, and unalloyed) in weak constant magnetic field (0.07 Tesla) has been carried out. The influence of weak constant magnetic field on the structure, mechanical and electrophysical properties of silicon, namely, increasing of internal defects density, forming of polycrystalline structure in unalloyed silicon, significant increment of microhardness and considerable degradation of minority carriers time of life has been noted. The qualitative explanations of magneto-stimulated phenomena in studied specimens from the viewpoint of spin-conversion as well as changes of electronic states density in the space-time as well as that of the influence of alloying elements on the critical points of first type phase transitions in silicon have been suggested. It has been found that using the weak constant magnetic field lets us to manage the properties of silicon by acceleration or slowing the shear and shear-diffusion phase transitions.
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    Development of welding consumables for wet underwater welding of high-alloy corrosion-resistant steel
    (Publishing House of Lviv Polytechnic National University, 2015) Kakhovskyi, Yurij; Kakhovskyi, Mykola
    This paper discusses a technology of mechanized wet underwater welding of high-alloy corrosion-resistance steel. The main aim of the investigation is development of self-shielded flux-cored wire for wet underwater welding for the first time in the world practice. A mathematical method of experiment design was used for determination of quantity and quality characteristics. Besides, quantitive and qualitative indices of welding-technological characteristics such as weld metal gas saturation, stability of arc burning in water medium, and optimum composition of gas-slag-forming components of flux-cored wire charge were determined. Problems of this branch and current ways of performance of welding – repair operations on objects of high-alloy corrosion-resistance steel were outlined. Application of experimental self-shielded flux-cored wire in mechanized wet underwater welding of high-alloy corrosion-resistance steel allows increasing efficiency and quality of underwater welding-repair operations and receiving economical effect due to reduction of production downtime of object under repair. Usage of present technology provides for the possibility of complete elimination or partial reduction of human participation in welding process under extreme conditions in radioactive environment (in the case of NPP) and in welding at greit depth. The results of researches can be used for weldingrepair operations in nuclear power plants, for ship repair and ship-raising operations and on hydraulic structures. Proposed innovation technology allows complete replacement of wet underwater welding using coated electrodes as well as eliminating human participation in welding-repair operations of critical structures under especially dangerous conditions such as underwater welding.
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    Identifying the elastic moduli of composite plates by using high-order theories
    (Publishing House of Lviv Polytechnic National University, 2015) Diveyev, Bohdan
    The study aims to predict elastic and damping properties of composite laminated plates from the measured mechanical characteristics. The elastic constants and damping properties of a laminated element are determined by using experimental data and the results of a multi level theoretical approach. Solution examples for particular problems are given. On the basis of static three-point bending tests, measured eigenfrequencies, and refined calculation schemes, the elastic properties of layered composite beams were identified. For determining Young’s and shear moduli, the method of genetic minimization of error function was used. It is shown that, by employing combined criteria, the transverse elastic moduli can be determined uniquely. It is shown that, by employing combined criteria, the transverse elastic moduli can be determined. The elastic modules were also determined from measured vibration eigen-frequencies of the beams. New combined criteria of identification – schemes averaged over the calculation results for a homogeneous beam and for a sandwich with a core identical to the homogeneous beam and rigid outer layers are considered. The error function is chosen as the sum of error functions for the homogeneous beam, and for the sandwich. In the present study, combined identification schemes making it possible to unequivocally determine the transverse modules and Poisson ratio are suggested.
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    The hydro-automatic damping system against dynamic vibrations
    (Publishing House of Lviv Polytechnic National University, 2015) Pelevin, Leonid; Karpenko, Mykola; Lavryk, Stanislav
    A review and analysis of the developed hydraulic system for quenching dynamic oscillations has been carried out. A mathematical model for determining the operation delay time of the hydraulic system of the dynamic quenching of oscillations has been created. A period’s calculation of cleavage of the soil and the operation delay time of quencher dynamic oscillations from which it is possible in theory to establish the ability of the hydraulic system of dynamic quenching of oscillations to operate in due time is performed. A hydraulic system of dynamic quenching of oscillations that occur inside the working unit to prevent the transmission of vibrations to the base of the machine is developed. The analysis of the damper’s means and the method of dynamic damping was conducted, based on which hydraulic system for dynamic quenching of oscillations has been developed. A mathematical sequence for determination of the operation delay time of the quencher was created. The parameters allow us to construct experimental model of hydraulic system for dynamic quenching of oscillations. The basic idea is the presence of feedback from the hydraulic system in the form of reed switch, which allows us in due time to turn on a pump and supply additional portion of hydraulic fluid for more efficient operation of the quencher. A hydraulic damping system which allows full vibroisolation is developed. At the expense of that, the average speed of operation is between 10–20 % of the period of soil cleavage.
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    The phase difference between components of elliptical oscillations of vibratory conveyor providing maximum conveying velocity
    (Publishing House of Lviv Polytechnic National University, 2015) Vrublevskyi, Іgor
    The piece goods conveying by the vibratory conveyor with elliptical oscillations is considered. Elliptical oscillations of the conveyor track are realized when conveyor has independent drives of oscillations in the direction of conveying (longitudinal oscillations) and oscillations in the direction perpendicular to conveying plane (normal oscillations) with phase difference between them. Elliptical oscillations allow increasing conveying velocity and inclination angle of conveyor track in comparison with the simplest linear oscillations. Conveying velocity of parts moving along the track of conveyor varies with the change of phase difference angle and reaches a maximum with a certain angle, depending on several different parameters. This angle is called the optimal phase difference angle, and it depends on the amplitudes and frequency of the component oscillations, the track inclination angle, the frictional properties, impact parameters of conveying parts. As the experimental investigations have shown, the piece goods conveying is quite accurately described by the theory of a massive point particle moving on an inclined plane under the action of vibration. A system of nonlinear differential equations describing the conveying in continuous contact modes and in modes with hopping was composed. This system has been solved by gradual integration method with numerical calculation with any desired accuracy. This allowed us to study the dependence of conveying velocity on different parameters in the form of graphs. And for greater generality the study was conducted in dimensionless parameters. There were studied in detail the influence of dimensionless parameters on dimensionless velocity – the coefficient of velocity that is the ratio of conveying velocity to amplitude of longitudinal oscillations with a constant frequency. To verify the obtained dependences, the experimental investigations of conveying velocity were carried out on vibratory conveyor with removable tracks. The conveyor was fastened on the turntable, the inclination of which was varied by a screw jack. The amplitude of the component oscillations was varied by changing voltage applied to the electromagnetic drives, the phase difference between component oscillations was varied by the phase shifter. Waveforms of oscillations were recorded by vibration measurement equipment. The coefficient of friction was measured directly during conveying. The velocity was measured by the stopwatch. The comparison of experimental results with theoretical data has shown the excellent agreement in continuous contact modes and the acceptable match in modes with hopping. Based on the obtained graphs, the approximate formulas for calculating velocity and optimal phase difference angle were derived. The influence of frictional properties of the conveying parts, namely, the coefficient of friction on optimal in terms of velocity phase difference angle between the longitudinal and normal components of the elliptical oscillations is investigated. It is shown that the optimal phase difference angle decreases with the increase in the coefficient of friction. The approximate formula of optimal phase difference angle dependence on the coefficient of friction and track inclination angle is derived.
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    Electromechanical model of machine for vibroabrasive treatment of machine parts
    (Publishing House of Lviv Polytechnic National University, 2015) Gorbatiyk, Ruslan; Palamarchuk, Igor; Chubyk, Roman
    A lot of operations on trimming clean and finishing – stripping up treatment, first of all, removing of burrs, rounding and processing of borders, until recently time was carried out by hand, and hardly exposed to automation and became a serious obstacle in subsequent growth of the labor productivity. Machines with free kinematics connection between a tool and the treating parts is provided by the printing-down of all of the surface of the machine parts, that allows us to effectively treat both internal and external surfaces of the machine parts. The analysis of literary sources, patents and charts of methods of the intensification of the processes of vibro abrasive treatment, allowed us to determine the basic directions of development of vibro machines constructions for intensification of the trimming - stripping of the machine parts in a freely granular environment in default of hard kinematic connection between the parts and the tool. The feature of vibro abrasive treatment is a free kinematic connection between a tool and the machine parts, i.e. there exists complication in providing with the stable beforehand set technologically optimum influence of abrasive grains on treated parts under variable parameters of the working chamber of vibroabrasive machine. The purpose of this work is the development of a structural electromechanical model of a vibromachine for adaptive vibroabrasive treatment of the machine parts. To solve this problem, the structural electromechanical model of vibromachine for adaptive vibroabrasive treatment of machine parts was developed. The offered machine is able to provide minimum energy consumption on the vibrodrive of vibroabrasive machine due to providing and maintenance of the permanent resonance mode of operations of working chamber.
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    Synthesis of structure and research of operation of resonance two-mass vibrating table with electromagnetic drive
    (Publishing House of Lviv Polytechnic National University, 2015) Lanets, Oleksiy; Borovets, Volodymyr; Lanets, Olena; Shpak, Yaroslav; Lozynskyy, Vasyl
    An industrial necessity of creation of 100-Hz vibratory tables is grounded. The prospect of researches of just resonance electromagnetic vibratory tables is conditioned. The existing vibrating tables on the basis of electromagnetic drive are considered. It is noted that the stages and problems which arise during the creating of high-frequency two-mass vibration table of middle sizes constructed according to classic chart are oulined in the article. The principle scheme of an electromagnetic vibratory table which is to be developed is described. The basic analytical dependences for determining the coefficient of inflexibility of the resonance resilient system and hauling effort of the electromagnetic vibroexciters are obtained. The construction of the upper plate of vibrating table is grounded, and its first eigenfrequency is determmined in order to avoid the coincidence with its forced frequency. The construction of vibrating table is given: its spatial model is presented, and the general draft and the draft of the two-mass vibratory system are also given. The inertia parameters of the oscillating masses are determined. The parameters of stiffness and structural parameters of the resonance resilient system are determined. Checking of the resilient elements for durability is conducted. The parameters of stiffness and structural parameters of vibration isolators are determined. The results of calculation of vibroexciter, according to the hauling effort with the use of the specially developed program, are presented. The theoretical gain-frequency description of vibratory table and time dependences of motion of the oscillating masses are presented. The experimental gain-frequency description of vibratory table and time dependences of motion of the oscillating masses, which absolutely coincide with the theoretical, are presented.
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    Robust mechanical system swith mechatronic devices: parameters identification and vibration control
    (Publishing House of Lviv Polytechnic National University, 2015) Chovnyuk, Yurii; Dikterjuk, Mykhailo
    The disturbance estimated with the help of advanced mechatronic devices is used for realization of robust mechanical system, such as agricultural machines. In the actual application, the estimated disturbance is effective not only for the disturbance compensation but also for the parameter identification in the mechanical system. The identified external force is applicable to sensorless force feed-back control in mechanical system and is utilized for a realization of mechanical vibration control. The progress of robust control technologies makes it possible to realize high performance motion control. In the industrial drive system such as a modern agricultural machine with advanced mechatronic device system for motion control, however, the developed technology is not enough to obtain the stable and high speed motion response since the mechanical vibration arises under the high accuracy positioning control. The mechanical vibration control is also taken in the field of the motion control. In particular, a vibration control based on the external force feedback brings the sophisticated advantages to the mechatronic system. The paper introduces a vibration control strategy based on the external force feedback called “resonance ratio control” in multiple resonance system. In this case, the external force may be obtained by using the identification process.