Ukrainian Journal of Mechanical Engineering and Materials Science. – 2016. – Vol. 2, No. 2

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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, 2016. – Volume 2, number 2. – 108 p. : il. – Паралельна назва англійською.


Recent Submissions

Now showing 1 - 11 of 11
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    Analysis of modern investigations of vibratory processes of wheeled vehicles
    (Publishing House of Lviv Polytechnic National University, 2016) Zalutskyi, Yurii; Zhytenko, Oleksandr; Kuzio, Ihor
    The history and modern tendencies of development of cushioning systems are analyzed in this paper. The development of mathematical modelling as a process is denoted, the methods and means are described and the necessary information of model choosing is presented. It is focused on the development of simulation modelling. The approaches of researchers, recommendations, indexes and specific features of evaluation of motion evenness are described. The works of many scientists are dedicated to analysis of car vibrations, evaluation of motion evenness and vibration-proof features. Many of them are devoted to investigation of vibrations, to optimization of basic design parameters of the cushioning system of cars and to development of new cushioning systems which allow reducing of vibratory overloading of trucks of general purpose. Taking into account the problems of motion evenness from the point of view of vibration of cushioning parts, the works of scientists are based on the linear theory of cushioning and the simplest one-mass car models are considered. It is also established that the drawback of usage of such theory consists in the fact that it is impossible to overview separately the vibrations of cushioning parts, which weight transfers to elastic elements of the suspension, and non-cushioning parts. The overview of scientific works dedicated to investigation of dynamics of wheeled vehicles allows to show the limited possibilities of traditional passive suspension system according to continuously increasing requirements to modern structures and to substantiate the necessity of usage of controlled cushioning systems. Among the existing variants of controlled cushioning systems, the half-controlled systems, which are the most optimal from the point of view of motion evenness increasing, energy consumption, complexity of structural implementation and usage safety, are of the greatest interest nowadays. On the basis of analyzed materials, it may be concluded that there exists a great amount of scientific investigations in the field of motor vehicles vibrations many of which are devoted to improvement of vibration-proof features of cars. Also a number of works are dedicated to investigation of vibratory overloading of industrial, construction and agricultural motor vehicles which are engaged in transportation of cargo of general purpose. However, too small attention is payed to development of techniques of determination of design parameters of cushioning systems of trucks which are engaged in transportation of cargo of special purpose, for example, cars transportation, where essentially greater attention should be payed to vibratory loadings which act upon such cargo during uneven motion.
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    Two-mass vibratory conveyor-manipulator with three-component electromagnetic drive
    (Publishing House of Lviv Polytechnic National University, 2016) Vrublevskyi, Іgor
    Vibratory conveyor with three-component oscillations provides the opportunity to move the piece goods and details for any trajectory on a plane. Phase difference between independent horizontal (longitudinal or transverse) and vertical (normal) oscillations releases elliptical vibration of conveyor in plane perpendicular to the conveyor’s track. Elliptical vibrations allow increasing conveying velocity and inclination angle of conveyor’s track in comparison with the simplest linear vibrations. Three-component oscillations of the conveyor’s track are implemented by independent exciters of oscillations in the direction of conveying (longitudinal oscillations), oscillations in the direction perpendicular to conveying in plane (transverse oscillations) and oscillations in the direction perpendicular to conveying plane (normal oscillations) with phase difference between them. Conveying velocity of details moving upon the track varies with the change of phase difference angle and reaches a maximum with a certain angle, depending on several parameters. When electromagnetic exciters of longitudinal and normal oscillations are turned on, conveying details move in longitudinal direction. When electromagnetic exciters of transverse and normal oscillations are turned on, conveying details move in transverse direction. When electromagnetic exciters of longitudinal and transverse oscillations are turned on, conveying details rotate around their axes. When all three exciters are turned on, conveying details move at any trajectory. The change in the ratio of longitudinal and transverse amplitudes and phase difference angles between them allows changing the trajectory of details moving on conveyor’s track, making them not only move forward but rotate as well. That’s why such conveyor can be called a manipulator. The resilient system of two-mass vibratory conveyor-manipulator with three-component oscillations should have elastic pliability in three mutually perpendicular directions. It includes four resilient elements; each of them consists of two latticed leaf springs, fixed at the right angle to each other. The working body with conveying track is joined with reactive frame by resilient elements. Electromagnetic drive includes four electromagnetic exciters of longitudinal oscillations, four electromagnetic exciters of transverse oscillations and one electromagnetic exciter of normal oscillations. The bodies of electromagnets are fixed on the reactive frame and their anchors are fixed on the working body of conveyor-manipulator. A block diagram of the electrical control of conveyor-manipulator is referred. A voltage is supplied from two phases of threephase electricity to the coils of electromagnets through diodes, auto-transformers, switches and phase-shifter. The amplitudes of oscillations are regulated with aid of auto-transformers, phase difference between them and the change of conveying modes are carried by switches and phase-shifter. The oscillating system of vibratory conveyor-manipulator has six degrees of freedom and respectively six frequencies of natural oscillation. The formulas for calculating the vibratory conveyor-manipulator’s frequencies of natural oscillation are derived. Vibratory conveyor-manipulator with three-component electromagnetic drive was designed and manufactured. Its research and testing show the possibility of conveying details and piece goods at any trajectory.
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    Ways of improvement of operational efficiency of hopper devices
    (Publishing House of Lviv Polytechnic National University, 2016) Koruniak, Petro; Shenbor, Vladyslav; Korendiy, Vitaliy; Bezpalov, Anatoliy; Brusentsov, Volodymyr
    The operation of hopper devices, which are used in industry, civil engineering, agriculture and transport, is analyzed on the article. The external factors, which influence the process of charging, storing and discharging of loose cargo (freights) from hopper tanks, are overviewed. The subject of research of presented paper is the improvement of mechanisms of fracturing of products hangs-up (bridges) in hoppers at the stage of designing and setting up of hopper devices. In order to solve the stated problem the schemes of bridges fracturing and the structures of devices for debarment of products bridging and their uniform outflow from the hopper tank are proposed. The proposed schemes are based on the principles used in development of vibratory machinery with mechanical, cam and electromagnetic vibratory principles of structures forming. For cam spring device of bridges fracturing the technique of calculation of stiffness of elastic system and of the necessary forces for performing of technological process of bridges fracturing is presented and the recommendations for choosing of the stiffness of the system of elastic elements are suggested. For the hoppers with spring and electromagnetic blocks of bridges fracturing and of metered (batched) feeding of products the structural diagrams of devices are presented and the recommendations for usage of various modifications of devices are suggested. The influence of parameters of flat spring elements on the efficiency of devices operation is overviewed. The structural diagrams of devices with one-cycle and two-cycle electromagnetic vibration exciters and the modifications of elastic systems are considered. the structural diagram of the production prototype of the hopper feeder is presented. The materials of the article, the proposed structural diagrams, the operation scheme of the hopper feeder and the derived analytical formulas may be used by designers, researchers and technologists while improving of existent and developing of new devices.
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    Experimental improvement of the technology of cutting of high-pressure hoses with metal braid on hand cutting machine
    (Publishing House of Lviv Polytechnic National University, 2016) Karpenko, Mykola; Bogdevicius, Marijonas; Prentkovskis, Olegas
    In the article the review of the problem of improvement of technology of high pressure hoses cutting on the hand cutting machines is analyzed. Different methods of cutting of high pressure hoses into the billets are overviewed and the quality of edge cuts of hoses is analyzed. The comparison of treatment on automatic cutting machines and on hand cutting machines is carried out. Different experimental techniques of improvement of the quality of edges cutting of high pressure hoses are presented. On the basis of experimental method, a new cutting technology which consists in maximally close fixation of high pressure hoses to the cutting disc is proposed. In the basic design of the hand cutting machine, the only supports are provided, so that the cutting of the edge section of high pressure hoses causes the metal braid loosening. The proposed technology excludes the scrolling and bending of high pressure hoses during cutting, so that the loosening of metal braid is also excluded. In the paper it is shown that the scheme of distribution of cutting forces during the cutting of high pressure hoses is presented and the mathematical model of determination of normal and tangential cutting forces is formed. With a help of tensiometric table the values of components of cutting forces during free and fixed cutting of high pressure hoses were defined and their comparison was performed. As a result of the use of this technology the edges of the cut off high pressure hoses meet the necessary requirements without using of complicated technological processes.
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    Investigation of the influence of machining factors on the workpiece deformation mode in the chip-forming zone by the finite element method
    (Publishing House of Lviv Polytechnic National University, 2016) Stupnytskyy, Vadym
    The results of studies of the impact strength, temperature factors and parameters of cutting tool geometry on the formation of the stress-strain and thermodynamic state of surfaces with different types of engineering materials in the cutting process are described in the article. Analysis of simulation modeling of power, temperature and deformation parameters is the basis for making of forecasting models of influence of the structure and process parameters on the formation of complex operational properties of the product.
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    Lathe turning mode optimisation for parts working under conditions of cyclic loading
    (Publishing House of Lviv Polytechnic National University, 2016) Barandych, Catherine; Vyslouh, Sergey; Antoniuk, Victor; Tymoshenko, Oleksandr; Koval, Viktor
    This work is devoted to questions of technological cyclic durability maintenance, of the material for parts working under cyclic loading conditions, by lathe processing optimization. The analysis of the impact of the surface layer quality on fatigue characteristics is described for parts operating under cyclic loads. Survey of methods for evaluating cyclic durability is completed, which showed lack of information about the mathematical relation between the cyclic durability of the part’s material and technological conditions of its production. A fatigue experimental study was carried out, the results of which allowed to create a mathematical model of cyclic durability of the material from lathe processing mode and tension cycle. The complex objective function that takes into account the dependence of cyclic durability of turning from technological conditions of handling and processing was developed. It is proposed to determine tension cycle for the most unsafe parts of a constructive element with consideration of conditions of service using the finite element method. The mathematical model of lathe processing of parts working under conditions of variable cyclic loads is developed and represented by total complex target function and system of constraints, including set of constrains on: feed, speed, strength and power of cutting, cutting precision, tool life and roughness of the workpiece. In addition, this mathematical model takes into account the actual characteristics of the material and expands its use to other materials of alloyed chromium steel. Submitted multi-criteria task is solved by using the method of sliding clearance. Steel 40Х GOST 4543-71 was used as an example for the proposed mathematical model of the part turning process, part operates under cyclic loading, and best values for feed and cutting speed are calculated.
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    Optimization of conditions of electroslag welding of bandings of rotary units
    (Publishing House of Lviv Polytechnic National University, 2016) Dzyubyk, Andrii; Dzyubyk, Liudmyla; Zinko, Yaroslav; Biruk, Stanislav
    The design of banding shells of rotary units is analyzed. It is shown that combined welding and cast manufacturing of bandings is used in the case of large structural sizes. The basic materials (30, 35, 25 HSL and 30 HML), being used in this process, are characterized by the tendency of forming of hardening structures due to the thermal cycle of welding. As a result of this, the cracks in the heat-effected zone, which lead to the destruction of the connection under the influence of welding residual stresses. The analysis of literature sources has shown that the usage of electroslag welding is perspective during the manufacturing and welding of operational cracks. Thus it is important to define the correct parameters of the welding conditions. In the case of electroslag method they are different from the arc methods and are characterized by the larger amount. In the paper the technological process of welding of banding (tread) ring with the external diameter of 4600 mm, wall thickness of 300 mm and wideness of 500 mm, which is made of steel 35. The defining of regime parameters is made using the following recommended techniques: taking into account the chemical composition of the basic metal; according to the nomogram depending on the ratio of the thickness of the metal to the number of electrode wires; using the calculation (design) method according to the conditions of electroslag welding of the banding. Taking into account the tendency of the steel 35 to cracks forming (cracking), the evaluation of the structure and phase composition and mechanical properties of metal of heat-effected zone of the weld. In order to define the microstructure, the cooling rate of the metal in the range of structural transformations was determined and the diagram of anisothermal decomposition of austenite was used. The technique of determination of the metal cooling rate as a result of the influence of thermal cycle of electroslag welding is proposed in the paper. It is based on the usage of special nomograms which characterize the specific features of the process being studied. The cooling rate equals w= 0.1876 degrees per second when using the developed process parameters. Also the investigation of temperature distribution in the cross-section of the weld has been carried out. It is shown that there are no significant deviations of temperature when using the proposed regime parameters. This influences the reduction of the level of residual stresses along the thickness of the weld. The analysis of the diagram of austenite transformation has shown that the structure of the steel 35 in the initial state is ferrite one with the mixture of pearlite and bainite. As a result of welding carrying out the structure will have a similar composition with slightly larger content of perlite and bainite. It was defined that their content in the heat-effected zone is as follows: 39 % for ferrite, 61 % for the mixture of perlite and bainite. At the same time, the investigated technology of electroslag process ensures the slow heating and cooling of the areas around the weld and obtaining of satisfactory mechanical properties of the metal. Therefore, the combined usage of existent techniques of regime parameters determination is expedient. Also it is necessary to carry out the verification of physical and chemical properties of the metal of heat-effected zone in order to prevent the formation of hardening structures.
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    Thermal processing of ZR-1 %NB tube in oxygenand nitrogen containing gaseous mediums
    (Publishing House of Lviv Polytechnic National University, 2016) Trush, Vasyl; Luk’yanenko, Alexander; Fedirko, Viktor
    Zirconium alloys have unique properties (physical, mechanical, radiation) is therefore are an essential structural material for nuclear energy. A feature of these alloys is high affinity to the interstitial elements (O, N). Saturation of oxygen and nitrogen occurs during the technological and exploitation heating. The dissolved interstitial elements greatly effect on the properties of finished products. The proposed results of experimental researches will expand the notions of patterns of relationship of the influence of elements interstitial on the properties of the zirconium alloy. The work presents results of the saturation of Zr-1 %Nb tubes after processing in oxygen- and nitrogen- containing gas environments. The distribution of micro-hardness and the size of the hardened layers in the section of the tube wall and the weight gain were determined. It is found that the oxidation of the Zr-1 %Nb alloy (Т = 650 °С, РО2 = 2.6·10-1 Pа, τ = 3…20 h) makes a greater weight gain than after nitriding (Т = 650 °С, τ = 5…20 h). The state of the surface of the inside and outside of Zr-1 %Nb tubes for fuel cladding depends of the processing time. The differences in saturation of outer and inner surfaces of the tube were registered. In particular, the hardness of internal surface of the tube is smaller relative to the outer surface after oxidation and nitriding processes. The results of study of the outer and inner surface of fuel cladding in contact with gaseous environment containing oxygen and nitrogen will be interesting for investigators of reactor materials.
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    Sound transmission properties of composite layered structures in the lower frequency range
    (Publishing House of Lviv Polytechnic National University, 2016) Diveyev, Bohdan
    This study aims to predict the sound transmission properties of composite layered plates structures in the lower frequency range. In present paper a novel procedure to derive the sound isolation parameters for layered plates is under discussion. This paper presents a new stress analysis method for the accurate determination of the detailed stress distributions in laminated plates subjected to cylindrical bending. Some approximate methods for the stress state predictions for laminated plates are presented here. The theoretical model described here incorporates deformations of each sheet of the lamina, which account for the effects of transverse shear deformation, transverse normal strain-stress and nonlinear variation of displacements with respect to the thickness coordinate. The main advantage of the present method is that it does not rely on strong assumptions about the model of the plate. Comparison with the Timoshenko beam theory is systematically made for analytical and approximation variants. The geometrical and mechanical parameters dependent frequency response functions and damping are presented for an arbitrary layered beam. The effective stiffness constants of equivalent to lamina Timoshenko beam (TB) and their damping properties have been determined by using a procedure based on multi-level numerical schemes and eigenfrequencies comparison. Numerical evaluations obtained for the vibration of the equivalent TB have been used to determine the sound transmission properties of laminated composite beams with the system of dynamic vibration absorbers (DVA’s). The optimization of beams – DVA’s system sound absorption properties is performed in the low frequency range. The results have shown that the presence of a DVA causes a decrease in the sound transmission in the low-frequency range. The extension of the present approach to various layered plates with various DVA’s systems will be performed in order to obtain optimal sound insulation.
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    Mag-welding of repair structures of main gas pipelines
    (Publishing House of Lviv Polytechnic National University, 2016) Maksimov, Sergii; Oleinik, Oleg; Gavrilyuk, Anatoliy
    Investigations on the development of a basic technology of the shielded-gas mechanized arc welding of strengthening structural elements which are used in repair of main gas pipelines were carried out. It is shown that the advanced welding wires Sv08G2S, Е71Т-1, DW-50, DW-A55 are in compliance with the requirements for providing the necessary level of mechanical characteristics, impact toughness of weld metal, content of diffusive hydrogen in the deposited metal and can be recommended for application in the further testing of technology for repair of the operating pipelines under the field conditions. The carried out works resulted in the working out of documentation on the technology of mechanized arc welding in shielding gases in repair of main gas pipelines of Ukraine.