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.

Electric pulse treatment of rim wheel metal after operation

Abstract: Introduction. Load increase on the wheel pair ax requires the use of railway wheels with the advanced complex of properties. Except strength properties, the properties of metal resistance to defect nucleation on the wheel thread are of high importance. The above mentioned properties increase is possible by using different technological decisions: alloying and heat strengthening. Purpose. The purpose is an attempt to estimate the softening degree of the wheel thread metal using the electric pulse treatment. Methodology. Electric pulse treatment (ET) was carried out on the special plant in the conditions of JSC DS (Nikolayev city). As the property of metal strength the Vickers hardness number is used. The microstructure research was carried out using the light microscope. The material for research is the carbon steel of the rim fragment of railway wheel №181732, withdrawn after operation, containing 0,55 % С, 0,74 % Mn, 0,33 % Si, 0,009 % P, 0,01 % S, 0,06 % Ni, 0,1 % Cr, 0,08 % Cu. Findings. Exposing the rim fragment to electric pulse treatment (ET), the qualitative changes of internal structure of the wheel rim metal corresponded to the experimentally observed geometrical dimensions change of the specimen, depending on the cycles number. As a result of the treatment the reduction of cold strained metal hardness is observed. It was found out 20 % softening on the wheel thread for the І rim area the, for the ІІ rim area the 8% softening and for the ІІІ 11% softening in relation to the initial state. Originality. As a result of electric pulse treatment, the change of the specimen geometrical dimensions is observed. Depending on the number of cycles it causes softening effect. It is proved that the observed softening value during ET is qualitatively connected with the cold strain level on the rail wheel thread. Practical value. As a result of metal cold work on the wheel thread its resistance to the defect nucleation is being reduced. The resulted data can be used during elaboration of measures to increase the operational safety of railway transport The technology development of the strain hardening embrittling influence reduce is an important scientific direction in further researches.

Research of Interference in the Operational Current of DC Motors of Railway Switch Points

Abstract: This paper deals with the research of interference in the current curve of DC motors of railway switch points and the diagnostics of using harmonic analysis of it during the operation. The current spectral composition of the DC motor with the series excitation was evaluated experimentally and theoretically. The influence of DC motors interferences on the adj acent railway automatics devices was investigated.

Rational steel corrugated profile design

Abstract: Purpose. The work sets forth the search results of new, more efficient design solutions for metal silos, namely, the analysis of existing types of profiles cross-section in a steel wall of such silo and development of less material-intensive section of corrugated profile. Methodology. To achieve the set goal there were researched the existing types of capacitive structure profiles and their strain-stress state under the load. The analysis was performed on the results of computational experiments. The prototype object was mathematical computer models. The calculations were made using the finite-element method. For computational experiment there was used the design-computing system Structure CAD for Windows. Findings. In this work there were obtained the data allowing to assess work of the profiles and to find more effective type of cross-section in terms of its material consumption. In the process of joint study of the authors a new type of profile for capacitive structures was developed; it has higher utilization efficiency and the attachment point of individual steel sheets with this type of profile. Both solutions are easy to install, reliable in operation and can be manufactured in the conditions of modern industrial production using standard equipment, materials and components. Originality. A new type of corrugated profile cross-section for steel silo walls was proposed; it has higher load carrying capacity and rigidity and allows reducing the metal thickness without changing the structure carrying capacity that results in material consumption reduction of the whole structure. For this and similar types of profiles there was designed and proposed the attachment point of individual corrugated sheets screwed with extending flange, which enables the unit connection in case of small size corrugations, where the distance is not sufficient to accommodate the bolt cap between the individual corrugations. Practical value. Application of the proposed solutions can increase efficiency, manufacturability and maintainability of steel silo wall structures. The results obtained during the research show promise for further development of research on finding new and more economic solutions for corrugated steel silo wall design, as well as other ways to reduce material consumption of bulk material storage structures.

Softening of hardened medium-carbon steel during heating

Abstract: I.Vakulenko: ORCID 0000-0002-7353-1916, S. Proidak: ORCID 0000-0003-2439-3657, L.Vakulenko: ORCID 0000-0003-2616-740X, N. Grischenko: ORCID 0000-0002-0091-1387

Determining of the equivalent and optimum diameters of cone-cylinder tip with soil broaching spurs

Abstract: Purpose. Building of new railway tracks and facilities, repair and replacement of existent underground utilities and communications is related to the receipt of horizontal cavities in soil by trenchless method. A static soil broaching with a working body with cone tip is the most widespread method in practice of forming a pilot hole at the trenchless laying of distributive communications. However, in the process of implementation of project calculations, receipt of pilot hole and subsequent expansion to the necessary sizes, there is a question of workings effort calculation methods. Existent methods are based on empiric dependences and experimental coefficients which diminish exactness of calculations and increase the cost of works. Methodology. The work proposes the dependence for determination of equivalent diameter of cone tip depending on the hole diameter and theoretical method for calculation of optimum parameters of soil broaching head using the well-known parameters: type of soil and its humidity, that determined by the State Construction Regulations (DBN). Findings. The results of the theoretical studies can be used to increase the efficiency of the working equipment for soil broaching by static method during trenchless laying of underground utilities and communications. Originality. The authors establish the dependence of the equivalent diameter of the cone base on the diameter of the cylindrical part of the broaching head, which allows for removal of the frictional force from the static broaching on the lateral cylindrical surface of the tip. Practical value. The obtained theoretical calculations for determining the optimal diameters of the cone tip with soil broaching spurs made it possible to establish that if the diameter of the cone is greater than the maximum diameter of the hole ( soil cavity ), then the frontal resistance of the cone - cylinder tip increases more intensively than the resistance of the cylindrical part of the tip . The maximum reduction in the broaching force takes place for a soil cavity whose diameter is 2 times smaller than the maximum limit diameter. When conducting the calculations regarding the choice of the size of working bodies for soil broaching, the source data include the type of soil, and its characteristics by DBN, as well as the moisture content of the soil determined by traditional methods.