Vol 19, No 2 (2018)

Mechanical engineering and power-plant
DETERMINATION OF CONTACT STRESSES AND GAPS IN CHAIN TRANSMISSION HINGES
Belousov Y.V., Strashnov S.V.
Abstract

The article considers the questions of determination of contact stresses in the chain transmission hinges that need to be known for assessing their wear resistance, because the wear and tear of hinges is the most common type of damage to the chain gears. In this context the main attention was paid to determining the required clearance between the bushing and the pin of roller chain drives. This gap largely determines the character of the distribution and magnitude of contact stresses in the hinge, and, consequently, the durability of chain drives. A method of calculation of the maximum contact stresses in the chain transmission hinges is developed. It is shown that decreasing clearance in the hinges increases the contact angle between the pin and the bushing and reduces the maximum contact pressure. However, for the actual angles of contact the contact stress greatly exceeds the allowable average unit pressure, causing increased wear of the hinges. One of the possible solutions to this problem is the use of transition fits in hinges, in which the gaps and interferences are relatively small. When pressing the pins into in the bushings, due to cutting microasperities from the contact surfaces, the interference in the connection virtually disappears. Examples of determining gaps and contact stresses in the chain transmission hinges are provided.

RUDN Journal of Engineering Researches. 2018;19(2):147-154
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COMPUTER-AIDED DESIGN OF TYPE C4: COMPRESSOR BLADE PROFILE
Vinogradov L.V., Mamaev V.K., Oshcepkov P.P.
Abstract

The paper presents the results of designing a compressor blade profile of type C4 using CAD, which implements the method of nonlinear transformation. Girst transformation was used by the authors. All calculations and graphical representations were made in the computer algebra system Mathcad. For the calculation and graphical representation the centreline is approximated with three nonlinear segments in the form of second order Bezier curve. After determining the first and last point of the second order Bezier curve, the coordinates of the middle point on the intersection of tangential lines that start at the first and last point of the curve are determined. After the approximation of three sections with second order Bezier curves the integral function of the blade back (convex side of the contour) of the profile C4 considering the leading and trailing edges are made as arcs. According to the analytical formulas, the geometric parameters of the curved profile were calculated, which are necessary for calculating the strength of the compressor blade.

RUDN Journal of Engineering Researches. 2018;19(2):155-164
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INFLUENCE OF ENERGY ON PHASE COMPOSITION OF END-PRODUCT OBTAINED BY VACUUM-FREE ELECTRIC ARC SYNTHESIS OF CUBIC SILICON CARBIDE
Pak A.Y., Mamontov G.Y., Bolotnikova O.A.
Abstract

The paper describes the scientific and technical basis of the vacuum-free plasma method for obtaining silicon carbide realized by DC arc discharge between graphite electrodes. In a series of experiments the energy supplied to the system was changed by increasing the duration of arc discharge with the constant value of current intensity (165 A); two precursor types were used: a mixture of silicon powder with X-ray amorphous carbon in the microfiber form in the first case and with carbon powder in the second case; the mass ratio in the initial mixture was Si:C = 2:1. As a result of the evaluation of the synthesis product quantitative composition, the experimental parameters that allow to achieve the maximum content of the target silicon carbide phase (up to 45%) are determined. Moreover, it was possible to determine the parameters when the only impurity phase in the product was graphite; as a result, the purification of the product from unbound carbon and thereby obtaining silicon carbide with ~99% content was successfully performed by atmospheric furnace heating at a temperature of 900 °C. This result is ensured by two factors: the presence of carbon fibers in the initial reagents mixture and a sufficient level of the supplied energy of about 216 kJ/g.

RUDN Journal of Engineering Researches. 2018;19(2):165-176
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PYTHON PACKAGE FOR INTELLIGENT CONTROL SYSTEMS SYNTHESIS
Diveev A.I., Dotsenko A.V.
Abstract

This article is devoted to the desription of аpython library based on symbolic regression methods for control systems synthesis problem. Control sysnthesis is becoming more and more relevant, gaining particular importance in view of the rapid development of robotics. Usually, practicians and engineers apply template-type regulators when modeling, and then select optimal parameters for them. At a time when the computing power of PC’s has reached its peak, and programming languages have become extremely expressive due to the high level of abstraction and the vastness of libraries, it is better to implement the synthesis in the form of a library. Python was chosen as the language for synthesis implementation. According to the authors of the article, Python is a convenient language for programming matrix and vector calculations thanks to the numpy package. Moreover, the share of projects written in Python in the web service for hosting Github has been steadily increasing recently, which indicates the support of the language from the developer community. This article describes how to use the package to solve the problem of control synthesis. The authors provide the description of the symbolic regression method, the network operator and algorithms for finding the optimal solution using the principle of small variations of the basic solution. In the experimental part of the article, an example of how to use the library to solve the problem of synthesis of control of a mobile robot moving on a planewith obstacles is considered.

RUDN Journal of Engineering Researches. 2018;19(2):177-189
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Architecture and civil engineering
NUMERICAL MODELLING OF POWERHOUSE STRUCTURE STRESS-STRAIN STATE CAUSED BY UNEQUAL SETTLEMENT AND DURING ITS LEVELLING OPERATIONS
Aleksandrov A.V.
Abstract

Reinforced concrete elements of the Zagorsk-2 pumped storage station structure had got into unexpected stress-strain state after unequal settlement and bending of the structure crosswise of the flow as a result. Cracks emerged in the load bearing reinforced concrete elements and the reinforcement crossing the cracks suffered significant tensile stresses. Important to mention, that the main reinforcement is arranged along the flow. There was a cofferdam designed and constructed across the reverse channel, which allowed to decreasethe water level and remove water from the channel to provide stabilized position of the powerhouse. After stabilization of the powerhouse, it was planned to level the powerhouse by the compensation grouting method.Based on the finite element soil-structure model of the powerhouse, the stress-strain state of reinforced concrete elements subject to unequal settlement and during the levelling operations was determined.The results of the stress-strain state analysis were compared with the actual in-situ stress data obtained by the “reinforcement de-stressing” method. According to the results of the analysis, it is necessary to strengthen the RC load bearing structures of the Zagorsk-2 powerhouse.In the article, the main design proposals for strengthening the RC load bearing structures of the Zagorsk-2 powerhouseby the external carbon fibre reinforcement are given and justified.

RUDN Journal of Engineering Researches. 2018;19(2):190-202
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NUMERICAL MODELING OF THE BUCKLING RESISTANCE OF RULED HELICOIDAL SHELLS
Giloulbe M., Markovich A.S., Tupikova E.M., Zhurbin Y.V.
Abstract

The paper concerns the buckling analysis of thin shells of right helicoid form. The buckling analysis was performed by the means of finite element software. Shells with variable pitch number and same contour radiuses and height were compared, their straight edges fixed and the curvilinear contours free. Was used for the analysis triangular shell finite elements (No. 42). The total number of nodal unknowns was the same in each of the considered tasks and was 16 206. Numerical investigation of the stability was performed by the finite element method in the software package Lira-Sapr 2017. The number of nodes in each task was the same. The loading includes combination of gravity (dead load) and vertical equally distributed load. The buckling mode and stability factor for every case is calculated. Boundary conditions - elastic built in shells along the bottom and top generatrices. To plot the midsurface of each shell were used parametric equations in rectangular coordinates. Of particular interest is the study of natural oscillations of the shells considered. To define the frequencies and forms of free vibrations is taken into account only the own weight of the helicoidal shells.

RUDN Journal of Engineering Researches. 2018;19(2):203-213
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RELIABILITY OF CONSTRUCTING RESIDENTIAL BUILDINGS USING STAY-IN-PLACE CEMENT BOARD FORMING TECHNOLOGY
Svintsov A.P., Koen A.R., Bisiev Z.A., Arsamakov I.Y.
Abstract

Using stay-in-place cement board forms for construction of residential buildings of reinforced concrete is one of the effective methods of modern construction. In the process of production of construction materials despite tight control some defects in structures may form. In this regard, the reliability assessment of the construction technology in terms of quality is an essential task. To assess the reliability of the construction technology the methods of visual examination of building structures and instrumental measurement of detected defects were used. Mathematical processing of the quantitative characteristics of the qualitative parameters is performed by methods of mathematical statistics with the confidence α = 0,95. The study established the most common defects of building structures erected with the stay-in-place cement board forms, as well as identified the cause-and-effect relationships of their formation. The probability of simultaneous failure of the task by the quality parameters of at least one characteristic varies from Qmin = 0,082 to Qmax = 0,161 with the average value Qcp = 0,119, the admissible value specified in building code being Qmin = 0,2. Overall, the technology of constructing reinforced concrete residential buildings with stay-in-place cement board forms corresponds to the level of reliability according to the quality parameters set by the project documentation.

RUDN Journal of Engineering Researches. 2018;19(2):214-227
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MODERN TRENDS IN THE DEVELOPMENT OF EQUIPMENT REDUCING HARMFUL PRESSURE FLUCTUATIONS IN PIPING SYSTEMS
Sinichenko E.K., Gritsuk I.I., Shesnyak L.E.
Abstract

The development of pipeline systems and the creation of new schemes, with the inclusion of additional equipment, poses high demands on the safety and reliability of the operation of injection plants, pumping stations, as well as on the elements of pipelines responsible for timely protection of the system in the event of emergency situations. The practice of operating long and short pipelines shows that fluctuations in pressure and flow caused by the operation of injection plants, as well as overloads of impact type, caused, in particular, by the operation of shut-off elements, result in additional dynamic loads on the pipeline, which can lead to accidents and catastrophes with severe consequences, human casualties. During the transient process in the individual sections of the pipeline, especially at the inlet and outlet of the injection plant, the pressure change can be so abrupt that it is possible to destroy the walls of the pipeline. Therefore, the problem of creating effective means of damping wave processes and hydraulic shocks has not lost its relevance for many decades. The article briefly describes the history of development of calculation methods of unsteady movement of a viscous and compressible fluid. The main problems are denoted in the practical operation of hydraulic systems, including various types of equipment. The references to articles which provide analysis of various aspects related to this subject are given.

RUDN Journal of Engineering Researches. 2018;19(2):228-234
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Innovative use of mineral resources
DEVELOPMENT OF TECHNOLOGY FOR SUPPORTING MINE WORKINGS UNDER CONDITIONS OF INTENSE OXIDATION OF SULFIDE ORES AT THE ORLOVSKY MINE
Shaposhnik Y.N., Konurin A.I., Shokarev D.A., Shaposhnik S.N.
Abstract

Goal. Metal frame supports SVP-22 with round timber lagging and backfilling of the voidsof unsupported space with chock support is used in the workings of unstable ores and rocks at the Orlovsky mine. When filling the voids with a chock supportmanually, people are located in an unsupported part of the working, therefore this operation is hazardous and laborious. The purpose of the work is to select and test the backfill material for voids of unsupported space, which ensures a decrease in diffusion and oxygen seepage to the centers of spontaneous ignition of the ore bodies under conditions of intense oxidation of sulphide ores at the Orlovsky deposit. Methods. Foaming non-combustible materials (“Blockfil” phenolic two-component resins) were tested in the experimental works at the Orlovsky mine for backfilling the voids when supporting the mine workings by metal frame supports with a round timber lagging. Results. It has been established that the use of phenolic resins as backfilling will reduce the intensity of the oxidation reaction and prevent self-heating of the ore to critical temperatures, and also prevent or slow down the process of heating ofmine air from the heated surface of the ore body to temperatures exceeding the design values. Conclusions. The use of phenolic resin “Blockfil” to fill the voids ensured the absence of deformation of the elements of the metal frame support and the safety of mining, and also allowed to reduce the intensity of the oxidation reaction and prevent self-heating from the ore to critical temperatures and prevent or slow down the process of heating the mine air from the heated surface of the ore body to temperatures, exceeding the design values.

RUDN Journal of Engineering Researches. 2018;19(2):235-245
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STUDY OF GRANULOMETRIC AND CHEMICAL-MINERAL COMPOSITIONS OF TOMTOR ORE DEPOSIT
Malkova M.Y., Zadiranov A.N.
Abstract

A study of the particle size distribution, mineral and chemical composition of the complex scandium-rare-earth-niobium Tomtor ore deposit has been conducted. It is shown that the basis of the ore is comprised of phosphates, carbonates and niobates. The main identified minerals are the minerals of crandallite group (gorceixite, goyazite and florencite), pyrochlore and monazite, in addition, clearly identified boehmite, apatite, and quartz. A group of other minerals includes siderite, kaolinite, rutile and some other minerals. It is established that the investigated ore belongs to a mineral variety of the pyrochlore-monazite-crandallite ores of phosphate-rare-metal type with a predominance of crandallite minerals (50%) and relatively low content of pyrochlore (~7%) in its composition. Based on the content of niobium oxide Nb2O5 (~4%) in a sample, the ore can be attributed to the second class according to the accepted classification, i.e. the rich niobium ores, containing from 3,5 to 9% Nb2O5. Tomtor ore deposit is also rich in the mineral content of rare earth elements. On the basis of the conducted research the conclusion about practical impossibility of beneficiation of “Tomtor” ore deposits by traditional methods and economic feasibility of ore processing by the combined pyro - and hydrometallurgy methods is made.

RUDN Journal of Engineering Researches. 2018;19(2):246-253
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PHYSICO-CHEMICAL TECHNOLOGY OF HEAP LEACHING AT MKUJU RIVER DEPOSIT IN TANZANIA
Kiselevskiy E.V., Kumbikila J.K., Usova V.M.
Abstract

Purpose. The purpose of this work was to examine various aspects of the physico-chemical heap leaching technology at the Mkuju River in Tanzania. The objectives of the study were to determine the basic geotechnological conditions of the Mkuju River uranium deposit, conduct laboratory work on the study of various technological parameters and rock characteristics, as well as a thorough analysis of geotechnological zoning. Methods. The objectives of the research have been solved using the generally accepted methodological approaches to solving problems on ores with a disturbed and undisturbed material structure that have been selected from wells drilled at the Mkuju River Mine in Tanzania, which are being explored and exploited for uranium. Results. Based on the conducted studies, the main geotechnological and geological-hydrogeological conditions, natural factors and their influence were determined. Also, laboratory studies helped determine the technological parameters and their optimal values. The conclusion. Underground leaching is influenced by a large number of factors, and the study of geotechnological conditions of deposits is the basis for a quantitative and qualitative assessment of the interrelationships of natural and industrial components of the natural-industrial system. In this case, after determining the factors the adaptation of the in situ leaching method to specific geological and hydrogeological conditions is established.

RUDN Journal of Engineering Researches. 2018;19(2):254-261
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Experience and opportunities of space systems applications of Earth remote sensing to prediction gold mineralization on difficult to approach areas (the Polar Urals)
Ivanova J., Ivanov K., Bondareva M., Ermolaev V., Zhukov A.
Abstract

The questions of the using of domestic and foreign spacecraft (SC), as well as Earth remote sensing (ERS) equipment for search and predication of gold mineralization on the example of the promising and difficult to approach areas of the Polar and the Northern Urals are discussed in the article. The solution of this problem is showed on the example of the prospective areas of the Arctic and the Northern Urals based on analysis of Landsat 7 multispectral images. Hidden structures (arc, annular, and radial) were detected with help of analyses of Landsat-7 imagery. Hidden structures determine the position of gold mineralization of the Toupugol-Hanmeyshorskogo (the Novogodnenskoe ore field, the Polar Urals) and the Turinsko-Auerbahovskogo (the Auerbachovskoe ore field, the Northern Urals) ore regions. The decision of this problem is given on the example of the promising territory of the Polar Urals with the use foreign SC the Landsat-7. Comparative analysis of the existing SC of ERS has been carried out, this target information has in the public domain. The onboard equipment installed on domestic spacecraft and the information obtained with use onboard equipment meets the existing requirements. These requirements are placed to onboard equipment to solve the problem of search and predication mineralization. At the same time, the capabilities of the deployed domestic orbital grouping of SC of ERS transcend the capabilities of SC of ERS the Landsat-7. Opportunity of obtaining geospatial information with the use of pseudospacecrafts is being considered. These have several advantages over SC and unmanned aerial vehicles.

RUDN Journal of Engineering Researches. 2018;19(2):
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