Ukrainian Journal of Mechanical Engineering and Materials Science. – 2017. – Vol. 3, No. 2

Permanent URI for this collectionhttps://ena.lpnu.ua/handle/ntb/42871

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, 2017. – Volume 3, number 2. – 118 p. : il.

Ukrainian Journal of Mechanical Engineering and Materials Science

Зміст (том 3, № 2)


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Content (Vol. 3, No 2)


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    Determination of stresses and ultimate loads for composite plates with elastic inclusions
    (Lviv Politechnic Publishing House, 2017-10-19) Jaroszewicz, Jerzy; Maksymovych, Olesya; Dzyubyk, Andrii; Nazar, Ihor; Bialystok University of Technology; Lviv Polytechnic National University
    In the article, the algorithm for determination of stresses in anisotropic plates with elastic inclusions of another anisotropic material was developed on the basis of complex singular integral equations. The solving of integral equations has been carried out numerically using the method of mechanical quadratures. The strength analysis (calculation of strength) of composite plates with inclusions has been performed using the Hoffman criterion.
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    Evaluation of dynamic characteristics of DPKr-2 diesel train on straight sections of railway track
    (Lviv Politechnic Publishing House, 2017-10-19) Kuzyshyn, Andriy; Batig, Andriy; Lviv Research Institute of Forensic Science
    The increase in motion speed of the trains moving along certain routs changes the operational conditions and interaction of the rolling stock and the track, and requires the solution of important issues related to the specifications of their maintenance, since there occur additional dynamic loads. In this case, the particular attention is paid to the interaction of the rolling stock and the railway track; to the problems of scientific substantiation of the criteria for assessing the dynamic characteristics of carriages; to the motion smoothness, traffic safety and travelling comfort; as well as to improvement of the maintenance specifications of the track and the rolling stock in the process of their operation and on the basis of scientific analysis and determination of top (safe) speeds of the trains motion. Using the three-dimensional mathematical model of the DPKr-2 Diesel train waggon, its basic dynamic characteristics were determined and analysed: coefficients of vertical and horizontal dynamics, maximum acceleration of the body both in vertical and in horizontal plane. The influence of the amplitude of vertical and horizontal obliques of the railway track on the dynamic characteristics of the Diesel train was investigated. The determination of the basic dynamic characteristics was carried out on the basis of the developed three-dimensional mathematical model of the waggon, which consists of 38 differential equations of the Diesel train motion. The simulation (solving) of the mathematical model was carried out using Maple software. The geometrical periodic equivalent obliques of the left and right rails were adopted as perturbations both in vertical and in horizontal plane. The determination of the basic dynamic characteristics of the DPKr-2 Diesel trane waggon will allow evaluating its vibro-protective properties. The determination of the coefficients of vertical and horizontal dynamics both in central and in axle leaf-spring suspension, of the maximum accelerations of the waggon body in vertical and in horizontal plane will allow carrying out the analysis of vibro-protective properties of the mechanical part of the Diesel train wagon. The obtained results may be used to define the safe interval of the Diesel train motion speeds on the track sections in the presence of vertical and horizontal obliques.
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    Functional performance of the main lighting system of motor vehicles
    (Lviv Politechnic Publishing House, 2017-10-19) Kachmar, Roman; Zhuk, Roman; Lviv Polytechnic National University
    Visual perception plays a crucial role in the safety of road users. However, certain conditions such as twilight, the impact of bad weather, dirty windshields, etc. have a negative impact, which in turn increase the likelihood of traffic accidents (TAs) [1]. The ever increasing number of vehicles on the road is an additional potential danger. In response to these factors work is constantly being done to modernize existing and develop new lighting devices. Vehicular headlights are firstly assigned to optimally illuminate the roadbed in order to ensure safety [2]. For this reason headlights, including their light source, are important safety elements for vehicles, and their application requires official permission. The type and location of vehicular lighting, as well as their design, light source, color and light settings are regulated by law [3]. Automakers pay sufficient attention to the fuel economy and safety of their vehicles. So for this reason automotive light sources, such as incandescent and gas-discharge (HID) bulbs, are increasingly being replaced by LED and laser diode bulbs as they provide superior lighting with lower power consumption. This in turn leads to increased vehicle safety and economy [3].
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    Gears with asymmetric tooth profiles and new alternative method of their manufacturing
    (Lviv Politechnic Publishing House, 2017-10-19) Hrytsay, Ihor; Lviv Polytechnic National University
    The article presents a new gears cutting process – radial circular generating method and describes its multiple benefits for manufacturers of transmissions. The overall increase of efficiency is realized due to using a simple tool and the conventional gear tool machine for cutting gears of different types. In particular, this new method was used for cutting gears with the asymmetric profiles of wheel teeth, which allows considerably amplifying power transmission density, increasing load capacity, and reducing size and weight.
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    Influence of the technological gap value of the tool-joint tapered thread on the drilling mud flow rate in its screw coupling
    (Lviv Politechnic Publishing House, 2017-10-19) Borushchak, Lubomyr; Borushchak, Stepan; Onysko, Oleh; Ivano-Frankivsk National Technical University of Oil and Gas
    Tightness is one of the parameters of the quality of pipe drill string. Consequently, the reduction of hydraulic costs and wear of the tool-joint tapered thread of the drill string can be achieved by changing the cutting part of the cut tools. It is precisely because of the reduction of the tightness we have bigger expense of hydraulic energy on the one hand and the wear on the surface of the thread is accelerated, since the drilling fluid together with the abrasive, moves along the screw threaded channel at a high speed (over 50 m/s) on the other side. To date, the tightness of tool-joint tapered thread provided in two ways. The second is the filling of the spiral channel, which is formed due to the standard gap between the box and the pin by a special lubricating and sealing filler. Typically, such fillers in the presence of significant pressure and untightness when contacting the ends of the box and pin are displaced from the channel. The authors of the article propose to reduce the cross-sectional area of the specified gap to achieve a sharp decrease in the speed of the drilling mud in the channel formed by the gap. As a result of the virtual experiment, actual data were obtained regarding the speed of the drilling mud, which became 40-50 times smaller in the case of a decrease in the height of the channel by 4 times and its width by 1.6 times. In the article it is shown that the existing sizes and tolerances for the gaps in the standard are of an optional nature and are presented for the design of a cutting tool for cutting. Consequently, the reduction of hydraulic costs and wear of the tool-joint tapered thread of the drill string can be achieved by changing the cutting part of the cut tools.
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    Investigation of magnetically controlled electric arc
    (Lviv Politechnic Publishing House, 2017-10-19) Biloborodchenko, Volodymyr; Dzyubyk, Andrii; Zabranskyi, Andrii; Lviv Polytechnic National University
    In this work, the results of pad welding with the circularly rotating arc existing in an inert gas between a circle cathode with the diameter suitable to dimensions and geometry of a welded surface, with the kinematic characteristics of the motion provided (with the rest equal conditions) by the external magnetic field, are considered. It is shown that the strict theory of an electric arc is insufficient for the description of real physical processes occurred in it under the action of external exciting magnetic fields, and so it does not allow conducting satisfactory technological calculations of the parameters of the pad welding process performed by the arc moved by the external magnetic field. The main problem consists in determining the effectiveness and the direction of superposition of electrodynamic and mechanical forces in it, which resist arc interaction with the magnetic field. Therefore, the aim of the work is to investigate the influence of the induction value В of the transvers magnetic field of a solenoid inductor on predicted kinematic characteristics of the arc. The investigations were conducted with the use of experimental equipment (test bench) consisting of a toroidal inductor with a winding. On the inductor, a nonfusible water-cooled ring copper electrode is mounted. Electrode dimensions agree with the diameter of pad surface. The shielding gas is provided through the system of radially located nozzles with discreet valvular operation, whose work priority is agreed with the arc motion velocity by a control unit. Since the values of abovementioned forces directly conditioned by the presence of a magnetic field in an interelectrode gap, the investigation of its intensity by the electrodynamic method with the help of the measuring instrument for magnetic induction ИМИ-1 was carried out. The analysis of the superimposed surface of the impact of the magnetizing current and the arc gap, which are used at pad welding by magnetically controlled arc, on the field induction shows that the range of their influence as technological mode parameters is quite narrow. Accordingly, for optimal choice of model nomographic solutions and the description of the correlation of parameters of the arc gap and magnetizing current, which provide the technologically suitable induction, an experiment was conducted according to the matrix of simplex-summarized С-С2 design. The investigations of a model extremum shows the acceptable induction value of 850∙10-5Т for the length of the electrode gap of 4 mm and inductor magnetizing current of 6 A. As a result, the proposed design of the test bench satisfies the geometrical parameters of renovated workpiece and enables using the effective repeated thermal pad cycle per unit of the surface by the rotating arc in the stable magnetic field. Settings of the magnetically operated arc, which provide the necessary value of field induction in the inter-electrode gap, can be determined either by nomograph solution, or by the strict statistic models. The influence of the length of the inter-electrode gap on the choice of the induction value is limited by technologically suitable pad current and corresponding length of an arc column. The main setting and controlling parameter of the magnetic field mode is the inductor magnetizing current. The force of resistance to arc motion at the stage of arc development and at the stage of arc steady motion is directly proportional to the value of the pad current. Calculated values of the velocity of arc motion at given values of the pad current are in the range relevant to its steady motion and provide the processes of anode melting without thermal damaging the ring cathode.
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    Investigation of the carbide-tipped tool wear hardened by method of aerodynamic impact
    (Lviv Politechnic Publishing House, 2017-10-19) Zhygalov, Anatoly; Stupnytskyy, Vadym; “Promlizing Corporation”, Belarus; Lviv Polytechnic National University
    Theoretical calculations and experimental studies of the influence of wear on the cutting process and the precision parameters of machining by hard alloys during milling are described in the article. The method of aerodynamic hardening is designed to increase the durability of tools, which are heterogeneous compositions of tungsten carbides, titanium and tantalum with cobalt ligature operating under severe process conditions with varying impact loads. The effect of hardening by the ADH method is achieved due to the influence of sound waves on the structure of hard alloys. The results of imitation studies of the wear process in the DEFORM system are described.
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    On free oscillations of a quadratic nonlinear oscillator
    (Lviv Politechnic Publishing House, 2017-10-19) Olshanskiy, Vasyl; Olshanskiy, Stanislav; Slipchenko, Maksym; Petro Vasilenko Kharkiv National Technical University
    A free oscillations of a system with one degree of freedom, caused either by the initial deviation from the stable equilibrium position or by the initial velocity provided by the oscillator in this position was considered. Analytical solutions of the nonlinear Cauchy problem for a second-order differential equation were constructed. The solutions are expressed in terms of Jacobi's periodic elliptic functions relating to occultation of special functions. Compact equals are derived for calculating the displacements of the oscillator and the oscillation periods for various methods of motion perturbation and for various variants of the elastic characteristic. The restrictions on the initial excitations for an oscillator with a soft elastic characteristic are determined, when its free oscillations are possible. The existence of a solution of the nonlinear dynamics problem in elementary functions is established. The behavior of an oscillator with a soft characteristic of elasticity under conditions of its freezing are studied. It is shown that from the derived equals, as special cases, the results known in the theory of linear oscillators, as well as oscillators with a purely quadratic nonlinearity, without a linear component, follow when the solution of the problem can be expressed in terms of Ateb-functions. The aim of the work was to derive new calculation equals for determining the displacements of a mechanical system with one degree of freedom under conditions of free oscillations, in the absence of friction. To achieve this objective, the representation of the second integral of the differential equation of motion due to the incomplete elliptic integral of the first kind were used. Using the known tables of the indicated integral, examples of calculations are given in which the probability of the derived equals is confirmed. According to the results of the study, it is also established that in the case of a quadratic elasticity characteristic of the linear component, the motion of the oscillator is described by the periodic elliptic Jacobi function, both in providing it with an initial deviation from the stable equilibrium position, and giving it the initial velocity in this position. In the case of a soft elasticity characteristic, free oscillations are possible only with certain restrictions on the initial perturbations of the system.
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    Optimization of welding modes for high-strength low-alloy domex 700 steel
    (Lviv Politechnic Publishing House, 2017-10-19) Dzyubyk, Andrii; Palash, Volodymyr; Khomych, Ivan; Hrynus, Stanislav; Lviv Polytechnic National University
    The microstructure and hardness of the weld joints of DOMEX 700 steel were investigated. As a result, the optimization of the parameters of robotic arc welding in the environment of protective gases was carried out taking into account the size of the energy per unit length. The optimum modes of welding were determined. The size of the deterioration area, where there is a decrease in hardness in comparison with the main metal, for a thickness of 6 mm is 2.36 mm, and for a thickness of 3 mm is 1.51 mm. The parameters of the robotic welding process in the arc mode in the environment of protective gases for the investigated thicknesses of the DOMEX 700 steel were recommended. As a result, the energy-saving conditions for welding performing were achieved ensuring the required technological strength.
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    Prospects of use of vibratory devices with electromagnetic drives for massive piece goods conveying
    (Lviv Politechnic Publishing House, 2017-10-19) Vrublevskyi, Igor; Hetman Petro Sahaidachnyi National Army Academy
    Vibratory conveying devices with electromagnetic drive are widely used in the different branches of industry. As a rule, they deal with relatively small piece goods and are not suitable for conveying of the large massive goods with high productivity. The conveying of massive piece goods needs the using of non-hopping modes of moving in which the high velocity can be reached only in the case of non-linear vibration trajectories of the conveying track, for example elliptical trajectories. Such trajectories are obtained by using of the independent drives of horizontal and vertical oscillations. Even greater velocity can be reached by using biharmonic vertical oscillation with particular optimal relations between amplitudes and phase differences of the component oscillations. These types of devices can be designed on a basis of three-mass oscillating system. Theoretical and experimental investigations show that the goods’ mass change significantly affects the vertical oscillations and weakly affects the horizontal oscillations. And at the certain relations between masses ratio and resonant tuning (ratio of frequencies of forced and natural oscillations) the vertical oscillations of active mass of two-mass vibratory device are insensitive to the change of goods’ mass. The sensitivity of vibratory conveying stability to the goods’ mass change was investigated for two-mass vibratory devices with elliptical oscillations. Three-mass oscillating systems with biharmonic oscillations in the point of view of the sensitivity to the goods’ mass changing were not considered. Analysis of different three-mass oscillating systems with electromagnetic drives of harmonic horizontal and biharmonic vertical oscillations allows determining two most preferable versions. The equations for amplitudes of components and frequencies of natural oscillations determining are derived. From the condition of insensitivity to conveying mass change the optimal relations between masses ratio and resonant tuning are obtained.
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    Structural and kinematic synthesis of the 1-Dof eight-bar walking mechanism with revolute kinematic pairs
    (Lviv Politechnic Publishing House, 2017-10-19) Korendiy, Vitaliy; Lviv Polytechnic National University
    Problem statement. The use of existing and the most widespread drives (wheeled and caterpillar one) is sometimes limited by complicated operational conditions while moving on rough terrain. The mentioned drives require a relatively flat surface to be operated effectively. A rocky or a hilly terrain imposes the demand of the use of alternative types of drives, in particular, walking ones. Purpose. In this paper, there will be proposed and analysed one of the possible structures of the walking mechanism for mobile robotic system to be used on rough terrain. Methodology. While carrying out the investigations, the structural and kinematic synthesis of the eight-bar hinge-lever walking mechanism has been performed using the well-known methods of the Theory of Machines and Mechanisms, in particular, the method of closed vector loops. In order to conduct experimental investigations and simulation of the mechanism motion, the applied software SolidWorks and MapleSim has been used. Findings (results). The structure and geometrical parameters of the eight-bar walking mechanism have been synthesized with the aim to ensure the required trajectory and kinematic characteristics of the supporting foot motion. Originality (novelty). The analytical dependencies describing the trajectory of each hinge of the analysed walking mechanism have been derived and the kinematic optimization synthesis problem has been solved. This allowed to substantiate of the mechanism’s geometrical parameters and to analyse its kinematic characteristics. Practical value. The proposed structure of the walking mechanism can be effectively used in various mobile robotic systems and in transporting and technological machines in order to ensure the possibility of their use on rough terrain where there is no ability to use wheeled and caterpillar drives. Scopes of further investigations. While carrying out further research, it is necessary to analyse the influence of the weight coefficients on the solution of the optimization problem, as well as to take into account the necessity of changing the step length and the foot lifting height during the process of walking according to the surface obstacles sizes.
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    Substantiation of parameters and analysis of operational characteristics of oscillating systems of vibratory finishing machines
    (Lviv Politechnic Publishing House, 2017-10-19) Korendiy, Vitaliy; Zakharov, Viktor; Lviv Polytechnic National University; ISKRA PJSC
    The calculation diagrams of oscillating systems and operation features of vibratory finishing machines are considered. The mathematical models of three-mass and four-mass oscillating systems are presented. The amplitude values of the oscillating masses displacements are derived. The functions of inertial and stiffness parameters optimization are formed. The optimization problems are solved with a help of MathCAD software. On the basis of synthesized inertial and stiffness parameters, the amplitude-frequency characteristics of the oscillating systems of vibratory finishing machines are formed and analyzed. In order to verify the validity of the proposed theoretical approaches, the simulation of the mathematical model of the oscillating system motion is carried out by means of numerical solving of the system of differential equations of the oscillating masses motion. The proposed structural diagrams and the operation schemes of the vibratory finishing machine, as well as the derived analytical formulas may be used by designers, researchers and technologists while improving existent and developing new equipment for vibro-finishing treatment.