Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan

About: Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan is a education organization based out in Dnipro, Ukraine. It is known for research contribution in the topics: Track (rail transport) & Bogie. The organization has 736 authors who have published 655 publications receiving 1468 citations. The organization is also known as: Institute of Railway Transport Engineers.

Diagnostic features research of ac electric point motors

Abstract: Purpose. Considerable responsibility for safety of operation rests on signal telephone and telegraph department of railway. One of the most attackable nodes (both automation systems, and railway in whole) is track switches. The aim of this investigation is developing such system for monitoring and diagnostics of track switches, which would fully meet the requirements of modern conditions of high-speed motion and heavy trains and producing diagnostics, collection and systematization of data in an automated way. Methodology. I n order to achieve the desired objectives research of a structure and the operating principle description of the switch electric drive, sequence of triggering its main units were carried out. The operating characteristics and settings, operating conditions, the causes of failures in the work, andrequirements for electric drives technology and their service were considered and analyzed. Basic analysis principles of dependence of nature of the changes the current waveform, which flows in the working circuit of AC electric point motor were determined. Technical implementation of the monitoring and diagnosing system the state of AC electric point motors was carried out. Findings. S ignals taken from serviceable and defective electric turnouts were researched. Originality. Identified a strong interconnectionbetween the technical condition of the track switchand curve shape that describes the current in the circuit of AC electric point motor during operation which is based on the research processes that have influence on it during operation. Practical value. Shown the principles of the technical approach to the transition from scheduled preventive maintenance to maintenance of real condition for a more objective assessment and thus more rapid response to emerging or failures when they occur gradually, damages and any other shortcomings in the work track switch AC drives.

Ensuring the durability of concrete in aggressive environment

Abstract: The article presents the results of experimental and theoretical studies, aimed at improvement of antisulphate stability of concrete in the structures, operated in conditions of a sulphate aggression. It has been shown that usage of a mathematical model of concrete anti-corrosion stability enables to calculate the ratio of anti-sulphate stability and to forecast the service time of the structures, made from reinforced concrete.

Physico-technological aspects of work of lubricant films in the tribosystem "overhead line – current collector contact strip"

Abstract: Purpose . The article aimed at comprehensive analysis of the processes occurring in the lubricant films of the friction surfaces of the tribosystem «overhead line – current collector contact strip» (OLCCCS) and identification of the features of such systems. Methodology . The systematic analysis was used as the main methodology for studying the physico-technological aspects of work of the lubricant films in the tribosystem «overhead line – current collector contact strip». Findings . The theory of electro-friction interaction is now at such a stage that is characterized by a large amount of accumulated empirical data, hypotheses and models that cannot adequately represent phenomena in a sliding, high-current electrical contact. The sliding electrical contact of the tribosystem «overhead line – current collector contact strip» during the operation is affected by many factors, one of which is the processes in the lubricating layers of the friction pair. The work leads to a new level of understanding of the peculiarities of the processes occurring in the lubricating layers and their effect on the work of a sliding, high-current electrical contact, which can become the guarantee of significant increase in the efficiency of such systems and, as a consequence, substantially increase the reliability and safety of the work of the electric stock. Originality . It is proposed to consider the processes of electro-friction interaction of electrical contacts from the position of synergy using the theory of fractals as the core one for the quantitative description of self-organizing structures. Practical value . Taking into account the empirical experience of operation of the tribosystem «overhead line – current collector contact strip» in combination with theoretical knowledge allows us to propose three possible directions for solving tribological problems in high-current sliding electrical contacts. They are: 1) change in contact geometry and surface topography, for example, the use of regular macrorelief of contact surfaces; 2) development of conductive composites which are characterised with self-lubrication, for example the use of composite materials containing solid conductive lubricants; 3) development of effective lubricants for electric high-current sliding contacts, which may require some complication of the component design.

Methods of investigation of thermal processes in the armatures of the motors switch processes in the armatures of the motors switch actuators

Abstract: The article considers issues of experimental research of thermal processes in the anchors of d. c. electrical motors in electrical drives of railway switching points. It has been proposed to determine the temperature of winding anchor insulation by the value of its capacity. This method allows to increase reliability and accuracy ofd.c.electrical motors diagnostics.

Microstructural Features and Mechanical and Tribological Properties of Fe–Cu–Ni–Sn Composites Precipitation-Hardened with CrB2 Additions

Abstract: The structural features, hardness, elastic modulus, and wear resistance of Fe–Cu–Ni–Sn composites with different CrB2 contents, produced by cold pressing and subsequent sintering with additional hot pressing, were studied by X-ray diffraction, scanning electron microscopy, microindentation, and tribological testing. The micromechanical and tribological tests were performed on composite samples 10 mm in diameter and 5 mm thick in dry friction conditions. The test results showed that the mechanical and tribological properties of the composites depended on the CrB2 content. The microhardness and elastic modulus of the samples varied from 1.2 to 9.2 GPa and from 110 to 245 GPa, respectively, depending on their composition, resulting from the uneven distribution of α-Fe, Cu, Cu9NiSn3, NiSn3, and CrB2 phases. The addition of 2 wt.% CrB2 to the 51Fe–32Cu–9Ni– 8Sn composite increased its hardness from 1.2–2.8 GPa to 2.0–4.5 GPa and the elastic modulus from 110–190 GPa to 130–200 GPa and decreased the wear rate from 22.93 ∙ 10–3 to 10.19 × 10–3 mm3 ∙ N–1 ∙ m–1. The mechanism of increasing the wear resistance of the composite sample containing 2 wt.% CrB2 in comparison with the starting composite was associated with the refinement of iron and copper grains from 5–40 μm to 2–10 μm and the presence of discrete areas of greater hardness and higher elastic modulus. A further increase in the CrB2 content from 2 to 8 wt.% in the composite was accompanied by a simultaneous increase in hardness from 2.0–4.5 GPa to 4.8–9.2 GPa, elastic modulus from 130–200 GPa to 150–245 GPa, and wear rate from 10.19 ×10–3 to 16.68 ∙10–3 mm3 ∙ N–1 ∙ m–1. The higher wear rate of these composites was due to excessive brittleness caused by excessive CrB2 content.