Ukrainian Journal of Mechanical Engineering and Materials Science. – 2022. – Vol. 8, No. 1

Permanent URI for this collectionhttps://ena.lpnu.ua/handle/ntb/60073

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 : Lviv Politechnic Publishing House, 2022. – Volume 8, number 1. – 52 p.

Український журнал із машинобудування і матеріалознавства

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    Mathematical model of dynamics of vibrating systems working environments
    (Видавництво Львівської політехніки, 2022-02-22) Topilnytskyy, Volodymyr; Kabanov, Kostiantyn; Lviv Polytechnic National University
    Using the apparatus of the special periodic Ateb-functions in combination with the asymptotic methods of nonlinear mechanics, the nonlinear mathematical models of motion of working environment of the oscillation system, which dependences take into account resilient and viscid making tensions from descriptions of the deformation state of environment, her physical and mechanical properties and features of co-operation of environment with the oscillation system, are worked out. The nonlinear model for describing the dynamics of the working environment of oscillating systems is more flexible, because the nonlinearity index, which depends on the type of working load, significantly affects the results of the oscillating loading process. It allows us to take into account the type of load, and, accordingly, increase the level of adequacy of the constructed analytical model of the oscillatory process that needs to be investigated. Taking into account this model, the study of various processes in oscillating systems can be carried out, in particular in different modes of vibration processing.
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    Contents
    (Видавництво Львівської політехніки, 2022-02-22)
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    Safety-overrunning ball-type clutch parts contact interaction features
    (Видавництво Львівської політехніки, 2022-02-22) Protsenko, Vladyslav; Malashchenko, Volodymyr; Kłysz, Sylwester; Avramenko, Oleksiy; Kherson State Maritime Academy; Lviv Polytechnic National University; Air Force Institute of Technology
    The article deals with the field of machinery, namely, with the protecting of devices for mechanical driving systems. Safety-overrunning clutches, operating on gearing principle, where safety and overrunning parts are mutually integrated, are perspectives for the building based on modular machines. This case is due to their compactness and low components, comparatively with combined constructions.New clutch design is investigated insufficiently. Particularly their calculation methods, namely parts contact stresses determination, developed deficiently. For balltype overrunning clutches, contact strength calculations are well-developed, but its transference on new construction safety-overrunning clutches is impossible because of the difference between parts contact interaction in those clutches. The aims of the article are: to analyze created by authors safetyoverrunning ball-type clutch parts contact interaction features; to propose on its base clutch construction improvement which could provide parts contact stresses minimization out of dependence with clutch manufacturing and assembling accuracy; taking into account Hertz contact interaction theory results, to obtain expressions for determining clutch parts loads and contact stresses. It is established that using safety-overrunning clutch grooves parallel to radius side surfaces is inexpedient. This can increase balls and internal semi-coupling grooves edge contact and significant contact stresses. To exclude the impact of clutch parts manufacturing and assembling accuracy on contact stresses in paper, proposed to incline grooves side surfaces at an angle to the semi-couplings radius, passing through the ball centre in diametric section. Comparatively,contact grooves inclination to radius with the edge allows decreasing contact stresses in 45–55 times. Further investigations should be focused on force parameters and operating characteristics justification for a clutch with inclined grooves proposed in this paper.
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    Analysis of vehicles drive with different characteristics of power supply
    (Видавництво Львівської політехніки, 2022-02-22) Myskiv, Teodozii; Sorokivskyi, Oleg; Lviv Polytechnic National University
    The characteristics of internal combustion engines (hereinafter referred to as ICE) have the following disadvantages: there is a gap between zero and minimum angular velocity, so it is impossible to move out of a state of rest; the dependence of torque on angular velocity is not ideal. They are corrected by the following converters: the first by a clutch or torque converter, and the second by a gearbox or variator. In addition, the ICE characteristics can be partially close themselves to ideal. Electric motors (here in after referred to as motors) of electric vehicles have an ideal characteristic that starts from scratch and has a large zone with a sustainable maximum power. The addition of the drive with the ICE motor in hybrid electric cars solves these problems. The different characteristics of ICE, motors and converters increase the number of possible configurations that affect the characteristics of the supply of power to the wheels. According to the traction characteristics of the car, the indicators of the traction and speed properties of the car are determined: the ability to overcome climbs, maximum acceleration, maximum speed on a horizontal road, acceleration time to a given speed, etc. The last two indicators depend primarily on the maximum power of ice or motor and are important for supercars, while for conventional cars or electric vehicles with close values of maximum speed and acceleration time to a given speed, they mean nothing. The authors propose to evaluate the efficiency of the drive during acceleration with maximum acceleration of the power utilization factor kN 0–100 – the particles from the division of the average value of the realized power on the wheels in the interval of speeds (0; 100) km/h by the maximum power value on the wheels. The characteristics of ICE and motors are given, traction characteristics in power coordinates are calculated – the speed of movement of cars with typical drive configurations, their power utilization coefficients are determined and appropriate conclusions are made. In the future, it is planned to investigate the use of power in more complex drive systems of hybrid cars with the recovery of braking energy.
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    Optimization of cyclone operating modes with intermediate dust removal using gas flow structure analysis
    (Видавництво Львівської політехніки, 2022-02-22) Maistruk, Volodymyr; Lviv Polytechnic National University
    The analysis of works in which designs of the dust collecting devices which are often used in the industry are investigated is carried out. It is established that forecasting the work of dust collecting devices in certain conditions is most effective to perform methods of numerical modeling and simulation of the separation process, which are widely used for research of devices of this type. Using numerical simulation methods, it is defined the structure of the gas flow in the cyclone with intermediate dust removal for different modes of operation, which was obtained by suction of gas through the dust unloading holes at constant total costs. For this cyclone, the change in the radius of the tangential, radial, and axial velocity component for different operating modes is investigated. In the course of the research, it is established that in the separation space the tangential component of velocity with increasing radius changes according to the parabolic law. The maximum values are 16–17 m/s. The suction of part of the gas in the amount of up to 20 % through the dust unloading holes slightly reduces the tangential component of the speed (up to 5 %) in the separation zone. It is determined that in the conical part the maximum values of the tangential component of the velocity decrease to 6–7 m/s. The reduction occurs both due to the flow of gas flow from the descending to the ascending, and the suction of gas through the dust unloading holes. It is established that the radial component of the velocity varies from 1 m/s in the separation zone to 5.5 m/s in the conical part. It has been found that the suction of gas through dust unloading holes in the amount of more than 15 % of the total volume leads to a change in the direction of the radial velocity component in the conical part. It is determined that the axial component of the velocity of the separation zone receives maximum values of 9–11 m/s. In the conical part of the device, it decreases to 2–4 m/s. The suction of part of the air through the dust unloading holes leads to a shift of the axis of the internal vortex relative to the geometric axis of the apparatus below the lower end of the exhaust pipe.It is established that the creation of a directed flow of gas through the dust unloading holes in the additional dust collector in the amount of up to 15 % of the total gas volume contributes to a more efficient operation of the dust collector. A further increase in the amount of exhaust air leads to greater turbulence of the flow and less efficient operation of the apparatus.
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    Effects of the yttria content and sintering temperature on the phase evolution in yttria-stabilized zirconia
    (Видавництво Львівської політехніки, 2022-02-22) Vavrukh, Valentyna; Lviv Polytechnic National University
    The microstructure of YSZ ceramics stabilized by the various amount of yttria, namely 3 mol % Y2O3 (3YSZ), 4 mol% Y2O3 (4YSZ) and 5 mol % Y2O3 (5YSZ) has been studied. Three sintering temperatures, namely 1450 °C, 1500 °C and 1550 °C were used for each series of samples (3YSZ, 4YSZ, 5YSZ). The total area of the monoclinic and cubic zirconia phases in the microstructure of ceramics and the regularities of distribution of these phases were determined by ImageJ. Peculiarities of changes in volume percentage of the monoclinic and cubic phases with an increase in sintering temperature of ceramics were found. Quantitative analysis of these phases was carried out. The total distribution of the monoclinic and cubic phases by ranges of their areas was presented. Correlations between the yttria content, the sintering temperature and changes in the microstructure and phase balance of the studied ceramics were found.
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    Modeling and simulation of machined surface layer microgeometry parameters
    (Видавництво Львівської політехніки, 2022-02-22) Stupnytskyy, Vadym; Dragašius, Egidijus; Baskutis, Saulius; Xianning, She; Lviv Polytechnic National University; Kaunas University of Technology
    The formation of the microtopography of the machined surface is one of the most critical factors in ensuring the effective operating properties of the product. These are indicators such as wear resistance, fatigue strength, provision of friction parameters of moving joints, etc. The most important reason for the formation of microroughness is vibration in the technological surface of the machine-tool-tool-tool-workpiece. This article is devoted to describing a new method of modelling the dynamic processes of machining. The peculiarity of this technique is using the results of rheological modelling (DEFORM). In addition, the consideration of regenerative vibrations of the tool is the difference of the described model. Regenerative oscillations arise due to surface roughness, which will be processed as a result of the previous technological stage of mechanical treatment. The mathematical model and the research results are described in the article. Recommendations for reducing oscillations are given.