Browsing by Author "Hnativ, Yuriy M."

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    Development of a Promising System for Diagnosing the Frogs of Railroad Switches Using the Transverse Profile Measurement Method
    (PC "Technology Center", Ukrainian State University of Railway Transport, Kharkov, 2018) Kovalchuk, Vitalii V.; Sysyn, Mykola P.; Hnativ, Yuriy M.; Bal, Olena M.; Parneta, Bohdan Z.; Pentsak, Andrii Ya.
    EN: We have developed a system for diagnosing the frogs of railroad switches, based on the application of modern microcontrollers of the type ESP with high technical characteristics and the simultaneous use of the information technology IoT (Internet of Things). The proposed system has advantages over mechanical systems in terms of the accuracy of data, their operational processing and submission to user in order to analyze technical condition of frogs at railroad switches. The results of measuring the transverse profile of frogs at railroad switches make it possible to take scientifically-substantiated decisions regarding the need for recovery repair of frogs by the method of surfacing and for control over gradual decrease in their carrying capacity, for establishing their actual technical condition and residual resource. We carried out experimental-theoretical research into longitudinal profile of frogs at railroad switches laid on the reinforced concrete bars. It was established as a result that after passing 50–65 million tons of cargo (that corresponds to the medium degree of wear) the trajectory takes the shape of a bump. We observe sharp hollows on the reinforced concrete base in the zone where a wheel rolls from a rail wing onto the core, characterized by significant total inclination. Subsequently, when the passed cargo increases, the number of sinusoidal irregularities grows. At wear close to maximal (80–95 million tons passed), the percentage of unfavorable trajectories (sinusoidal and hollows) grows; at low wear, they make up 49.8 %, at a wear of 5−6 mm and larger – 88.3 %. Sometimes there is a transformation of the sinusoidal irregularities into the wave-shaped ones. We have established characteristic motion trajectories of the center of mass of the wheel over the frog depending on the wear of rail wings and the core of a frog and the passed cargo. A mathematical model was constructed for predicting the wear of frog profile depending on the total weight of passed cargo.
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    Investigation of KPP-5 Rail Fastener Elastic Deformation
    (Universiti Malaysia Pahang, Malaysia, 2018) Marcul, Ruslan V.; Nastechik, Nicolai P.; Kovalchuk, Vitalii V.; Hnativ, Yuriy M.
    EN: For a long period of operation, a number of shortcomings have been identified in KPP-5 fastener that is mainly due to an intensive decrease of pressing force of the rail on leepers. This leads to the appearance of frequent cases of track displacement and fastening elements failure. To verify such hypothesis, the process of power work of KPP-5 fastener during railway track operation was researched. The technique and practical means of controlling the power work of KPP-5 fastener are developed. The influence of various factors of the rail pressing force on the sleeper is determined. The main influence is conditioned by under-rail wear (50.4%). The obtained results made it possible to formulate recommendations for the improvement of KPP-5 fastener where the methodology and practical means of controlling the power work of KPP-5 fastener were proposed. At the same time, it allows increasing the reliability and safety of the rail track during the entire overhaul period.
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    Method of Calculation of Temperature Field and Deflected Mode of Bridge Structures in Software Environment NX NASTRAN
    (Szcześniak, Warsaw, 2013) Luchko, Josyp; Hnativ, Yuriy M.; Kovalchuk, Vitaliy V.
    EN: Abstract: Designs of bridges and overpasses during operation are sustained to complex climatic factors. Study of heat exchange components is an integral part of preparation data for thermal stresses and deformations calculation. Sequence determination of thermal stresses and deformations of bridge structures. Close conditions of the structural elements of modern bridges and overpasses, a variety of their shapes, materials and sizes result in extremely difficult and expensive full- or part-scale investigations. In this regard, there is need to develop and apply various computational approaches that allow relatively in a short time and with little cost to obtain data about engineering structures.
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    Restoration of the Bearing Capacity of Damaged Transport Constructions Made of Corrugated Metal Structures
    (RTU Press, Latvia, 2021) Kovalchuk, Vitalii V.; Sysyn, Mykola P.; Hnativ, Yuriy M.; Onyshchenko, Artur; Koval, Maksym; Tiutkin, Oleksii L.; Parneta, Mariana
    ENG: The paper deals with damages of transport constructions made of corrugated metal structures in the body of a railway track or a road during their operation. A constructive variant to restore the bearing capacity of structures was developed, which consists of installing an annular stiffening rib into the concave part of the corrugated metal profile. The main advantage of this method compared to the double corrugating method is the possibility of performing the reinforcement works during structure operation without interrupting the movement of transport vesicles. The study has proved that the reinforcement method significantly increases the carrying capacity of corrugated metal structures. A numerical finite element model was developed to determine the stress-strain state of structures made of corrugated metal structures reinforced with round stiffening ribs. The soil pressure on the corrugated shell in the model is taken into account with the application of radial and axial forces on the outer surface of the shell. It was determined that the most appropriate location of the ribs is in the centre of the building, where the reinforcement area corresponds to the width of the road or railway line. The advantage of this approach is the ability to more efficiently distribute the reinforcement material by selecting the ribs in the most loaded sections of corrugated metal structures.
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    Study of the Temperature Field and the Thermo-Elastic State of the Multilayer Soil-Steel Structure
    (Institute of Roads and Bridges, Poland, 2020) Kovalchuk, Vitalii V.; Hnativ, Yuriy M.; Luchko, Joseph; Sysyn, Mykola P.
    EN: The technology of renewal of metal corrugated structures allows efficient and economical reconstruction of existing reinforced concrete structures by the method of encapsulation. However, such structures can be exposed to adverse temperature effects that in combination with traffic loadings could influence the operational reliability of the structures. This article deals with the method of evaluation of the stress-strain state of a three-layer cylindrical structure. The technique is based on the thermo-elasticity theory. The study is performed in two steps: determining the temperature field of a structure, and then calculating the temperature stresses and deformations. As a result of calculations, it was established that the level of temperature field and stresses in a three-layer structure caused by the maximum and minimum ambient temperatures can reach a significant level.