Кафедра "Прикладна механіка та матеріалознавство" <br> (з 2016 року об'єднано каф. "Прикладна механіка" та каф. "Технологія матеріалів")

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http://crust.ust.edu.ua/handle/123456789/660

ENG: Department of Applied Mechanics 2016 Department of Applied Mechanics Department of Material Technology

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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.
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.
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 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.
Simulation Modelling of the Rolling Stock Axle Test-Bench
(EDP Sciences, 2019) Raksha, Serhii V.; Anofriev, Pavlo G.; Kuropiatnyk, Oleksii S.
ENG: Abstract. Wheelset axles are essential parts of railway and mine site rolling stock. For fatigue testing of axles, various test-benches are designed to implement the cyclic loads. The effectiveness of test-bench vibration analysis grows with the use of numerical approach and simulation models created with the aid of visual programming tools. The purpose of the work is to develop and assess the proposed simulation models of test-bench dynamics created with the aid of visual programming tools. Based on mathematical models, the test-bench simulation models of the lever system vibration have been developed. Simulation models are created with the aid of Simulink visual programming tools running under Matlab system. For modelling the components of Simulink, the SimMechanics and DSP System Toolbox Libraries are used. The comparative analysis of proposed models has been made. For the first time, with the aid of Simulink visual programming tools, the set of test-bench vibration simulation models has been obtained in steady-state and transient motion modes for linear task formulation. The proposed S-models allow automation and visualization of the motion dynamics study for test-bench components in order to determine their rational elastic-weight, kinematic and dynamic behavior. Simulation of vibrations was carried out using design parameters of the test-bench metal framework.
Stand for Accelerated Tests of Rail Vehicles Wheelsets
(IOP Publishing, 2020) Raksha, Serhii V.; Anofriev, Pavlo G.; Kuropiatnyk, Oleksii S.
ENG: Tests and research can be greatly accelerated by applying a multi-point load to the test wheel. The aim of this work is to substantiate rational parameters of the stand for accelerated life tests of railway wheelsets, in which a multi-point load applies to the rolling surface of the test wheel. On the basis of the laws of the theory of elasticity, we performed analytical calculations of the contact stresses created by the rolling bodies of the load mechanism of the test stand. Research has shown that the dependence of the contact stresses on the wheel rolling surface on the ball’s diameter is nonlinear. The decrease in stress is due to an increase in the contact area. We obtained the analytical and graphical dependencies, which make it possible to evaluate the influence of the parameters of the stand for accelerated life tests of railway wheelsets on contact stresses on the wheel rolling surface, taking into account the shape and dimensions of this surface. The authors have proposed a stand design for accelerated life tests of railway wheelsets. The use of a stand with the parameters justified in this work will reduce the test duration by 10-15 times.
Substantiation of the Parameters of the Bench for Testing of Railway Wheels for Contact and Fatigue Strength
(Technologija, Kaunas, 2022) Raksha, Serhii V.; Anofriev, Pavlo G.; Kuropiatnyk, Oleksii S.; Glavatskij, Kazimir Ts.; Bohomaz, Volodymyr M.; Posmitiukha, Oleksandr P.; Volkova, Svetlana A.
ENG: Strength indicators are important parameters of the railway wheels, as they determine the allowable service life of both the wheel itself and the wheelset as a whole. Therefore, the development of bench equipment that allows in the laboratory to reproduce or simulate the real conditions of the wheel load in order to conduct strength tests, is an urgent scientific and practical task. The purpose of this work is to substantiate the parameters of the bench for testing railway wheels for fatigue and contact strength. As the bench has to test railway wheels for fatigue and contact strength at the same time, the requirements of various normative and methodological documents, which determine the procedure for conducting such tests on separate benches, were combined when determining the parameters of the bench. We determined that the working force of the bench should vary from 10% to 100% of the wheel endurance limit, the duration of the tests should correspond to five million load cycles with a frequency of 5 to 10 Hz. To reduce the duration of the tests, pushing on the wheel was carried out by several rollers, which were evenly distributed around the wheel. For the proposed bench, we obtained the dependence that connects the parameters of the test wheel, the parameters of the bench, the wheel pair axle load and the wheel material endurance limit. The results of this study can be used as a basis for the development of new schemes of benches for railway wheels tests.

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Browsing Кафедра "Прикладна механіка та матеріалознавство" <br> (з 2016 року об'єднано каф. "Прикладна механіка" та каф. "Технологія матеріалів") by Author "Anofriev, Pavlo G."

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