Статьи журнала - Siberian Aerospace Journal
Все статьи: 363
Influence of a constant electric field on the adsorption purification of water from iron ions
Статья научная
Using electrochemical action (ECA) to treat water was first proposed in UK in 1889. At present, many methods of ECA are known (electro flotation, electro coagulation, electro osmosis, electrophoresis, etc.). In the production of rocket and space technology, galvanic technologies are used, as a result of which waste water is contaminated with metal ions. Known methods of wastewater treatment do not allow to ensure the maximum permissible concentration of metal ions in treated water, or are expensive or difficult to operate in industry. Iron ions are among the most polluting components of wastewater of most industries. So increased control and the development of effective methods of wastewater treatment are necessary. Iron affects the intensity of phytoplankton development and the qualitative composition of microflora in reservoirs. The toxicity of iron compounds in water depends on the hydrogen index of water. The alkaline environment dramatically increases the risk of fish poisoning, as in such conditions, iron hydroxides are formed, which are deposited on the gills, clog and corrode them. In addition, iron compounds bind oxygen dissolved in water, which leads to the mass death of fish and other hydrobionts. The article presents the method of conducting experiments, the methods of sorption, electrochemical and combined water treatment, including electrochemical action and adsorption. The results of studies of these methods of water purification from iron ions are presented. The dependence of the degree of purification on the electric field strength, interelectrode distance and water treatment time is revealed. With an electric field strength of 5.16 V/mm, a temperature of 20–22 °C using quartz sand as an adsorbent and a processing time of 1 minute, the concentration of iron ions decreased from 2.5 to 0.25 mg/l (at MPC = 0.3 mg/l). The proposed combined cleaning method requires inexpensive and affordable materials and is easy to operate.
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Статья научная
The properties of a solid solution of thulium-substituted manganese sulfide prepared by melting the ini-tial pure samples of manganese sulfide and thulium sulfide are studied. X-ray diffraction analysis was car-ried out. The face-centered cubic lattice is determined, and the decrease in the intensity of the peaks is found. Dielectric permittivity was measured in the frequency range 102–106 Hz and temperatures 300–500 K in magnetic fields up to 12 kOe in TmxMn1-xS solid solutions (0 < x < 0.15). From the frequency depend-ence of the permittivity, the relaxation time and the relaxation mechanism of the dipole moments are found. The leakage current is excluded, and the contribution of migration polarization due to charges in the re-gion with chemical phase separation is estimated. The real and imaginary components of the permittivity of TmxMn1-xS samples are described in the Debye model. The maximum of the imaginary component of the permittivity shifts towards higher frequencies upon heating, and the relaxation time is described by the Ar-rhenius function. Dielectric losses are caused by electron-phonon interaction. The frequency of the crosso-ver from Debye relaxation to relaxation conduction associated with the absorption and emission of pho-nons is found. The crossover frequency increases as the sample is heated according to a power law. In a magnetic field, the permittivity decreases and the largest change of 2.5 % is achieved at T = 450 K. At oth-er temperatures, the magnetocapacitance does not exceed 0.5 %. The shift of the maximum of the imagi-nary component of the permittivity to low frequencies in a magnetic field leads to a change in the sign of dielectric losses from positive to negative. A qualitative difference in ε(ω) is established in the vicinity of the concentration of thulium ion flow through the FCC lattice, where the permittivity is not described in the Debye model and there is no magnetocapacitance. The mechanism for reducing dielectric losses in a mag-netic field is determined.
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Influence of plasma jets of electric jet engines on spacecraft functional characteristics
Статья научная
The issues of compatibility of correcting electric jet engines (EJE) and large-size transformable antennas (LTA) used in high-orbit communication satellites are considered. The paper deals with the erosive and polluting effect of EJE jets interacting with knitted mesh material (grid mesh), which is used for manufacturing LTA reflectors. The erosive effect of the EJE jets on the LTA mesh is characterized by the fact that the angles of ions incidence on the surface of the threads in the mesh are in the range from 0 to 90, i. e. such effect takes place at practically any angle of ions incidence on the mesh surface. The research includes both mathematical description of physical processes and conducting a wide series of experiments, which makes it possible to achieve the necessary reliability of the results. It has been established that the effect of plasma jets of correcting engines can lead to significant sputtering of the reflecting coating from the surface of a large-size antenna reflector. The authors obtained experimental data on the degradation of the reflection coefficient of electromagnetic radiation from the mesh, depending on the degree of plasma jet influence. It was found that the sputtering of reflecting coating from the surface of threads does not significantly affect the reflection coefficient. The sputtering of the coating at the points of threads contact is much more significant. Strong dependence of the reflection coefficient on the type of mesh weaving was also found. The mechanism of sputtering products deposition on reflecting coatings of the thermal control system radiators was investigated. The results of calculations of the sputtering coefficient and the sputtering indicatrix of the reflecting coating applied to the mesh threads were obtained. The degradation of the functional characteristics of thermoregulatory coatings (TRC) during the deposition of thin films of gold, which is one of the possible materials for a reflecting coating, was experimentally determined. Estimates of the maximum permissible level of TRC contamination were obtained. It is shown that, subject to the relevant design rules, it is possible to use EJE and LTA together in high-orbit communication satellites.
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Статья научная
Due to the absorption of solar energy in chloroplasts – green plastids, solar energy is converted into the energy of chemical bonds. Studying the processes of photosynthesis and increasing its efficiency is relevant for the development of closed life support systems, during long flights in space as well. Chloroplasts are filled with stacks of highly ordered thylakoid membranes (grana). Pigment-protein photosynthetic complexes are located on the border of these membranes. For a long time, the structural characteristics of chloroplasts were not given due attention and they were studied as isotropic substances, but in recent years it has been shown that they have anisotropic properties and a high conversion coefficient during charge separation. In this work, an approach was proposed for a more accurate spatial determination of grana in plant chloroplasts and for determining the size of a single unit. Thylakoid membranes and the boundaries of the facet consisting of them are clearly visible in an electron microscope if the electron beam is directed strictly perpendicularly. It was noticed that when the stage is rotated, different regions of the membranes become either blurred or more distinct, which suggests that the grana in chloroplasts are not located in the same plane. Also, a comparison was made of the influence of different external conditions on the chloroplast structure of a plant, not only through a comparison of morphological characteristics, but also through numerical modeling and comparison of the objects spectral properties. For numerical simulation, periodic lattices were determined for the main structural units of chloroplasts of different samples. On the basis of these gratings, the transmission spectra were calculated using the transfer matrix method. Also, the obtained values of the electromagnetic wave along the lattice made it possible to calculate the graphs of the density of photon states. The results of the calculation method of plots of the density of photon states based on the structure of chloroplasts made it possible not only to assess the possible efficiency of photosynthesis, but also to directly relate these models to the external conditions affecting the plant.
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Influence of the magnetic field on transport properties of holmium – manganese sulfide
Статья научная
Holmium-manganese sulfide with giant magnetoresistance refers to new magnetic sulfide compounds of holmium and manganese that have the effect of giant magnetoresistance (i. e., with special magnetoelectric properties), which can be used as components of sensor technology, magnetic memory, and spintronics. The technology of manufacturing polycrystals HoXMn1-XS grown by crystallization from the melt of the obtained powdered sulfides with a purity not lower than 99,9 %, in glass-carbon crucibles and a quartz reactor in an argon atmosphere is presented. According to the results of x-ray diffraction analysis, HoXMn1-XS holmium-manganese sulfides have a HCC structure of the NaCl type. As the degree of cationic substitution increases, the unit cell parameter increases linearly with the concentration. No concomitant impurity phases are detected in the synthesized samples. To determine the state of the spin glass, magnetic moment measurements are conducted at several frequencies ω = 1 kHz, 10 kHz and 100 kHz. The dependence of magnetic characteristics on the frequency of measurements is found. The damping of the magnetic moment and its increase with a decrease in temperature is reviled, which is connected with the formation of metastable States. Measurements of electrical resistance without a field and in a magnetic field are conducted. Anomalies in the temperature dependence of the conductivity are found. A change in the magnetoresistance sign is detected with the increase of temperature below and above room temperature.
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Information-measuring system of pyrometric type for small-sized unmanned aircraft
Статья научная
A new trend of science and technology is now rapidly developing both in Russia and abroad – the development of miniature unmanned aerial vehicles. The key system of on-board control equipment (avionics) of an unmanned aerial vehicle (UAV) is the orientation system for determining UAV attitude relative to reference system. In small-size UAV, we can meet the application of strapdown attitude reference systems, magnetometric, pyrometric, video systems, etc. Rapid development of mini- and micro-UAVs requires the development of information-measuring systems (operating on different physical principles) in order to determine UAV attitude parameters in flight. With UAV mass and wingspan reduction, there are growing requirements for these systems, concerning the accuracy of positioning parameters and more compact dimensions. Manufacturing of most information-measuring and control systems of manned aircraft and heavy UAVs rely on traditionally used gyroscopes and accelerometers. They are complex fine-mechanics instruments of considerable power consumption, rather large size, weight and high cost. A significant improvement of the accuracy in UAV angular coordinates determination is achieved by integrating orientation systems of various types. The use of GPS / GLONASS signals also improves the accuracy and reliability of determining UAV angular coordinates and supplies the additional function of measuring its geographical coordinates.
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Infrastructure for collecting data and simulating security threats in the internet of things network
Статья научная
The implementation of the internet of things technologies in the rocket-space industry requires increased security measures for information and communication processes. Existing intrusion detection systems are unable to take into account the heterogeneity of the network structure and the scale of information circulating between devices. To solve this problem, intrusion detection systems use an anomaly method, which requires a large number of representative data sets. The authors have reviewed public datasets that can be used to build an anomaly detection system. They contain information from artificial simulation medium or isolated environments with simulated devices, include examples that are not directly related to the internet of things, and do not take into account the dynamic nature of traffic changes. In this paper, we present a new infrastructure that will avoid these drawbacks. It collects data on the functioning of a real Internet of Things network and allows testing its stability to typical attacks. We use the MQTT (message queuing telemetry transport) application protocol and software platforms that support information interaction based on the publisher-subscriber pattern. The infrastructure contains devices that monitor technological rooms with telecommunications equipment, brokers with various security policy set-tings, applications for data control and analysis, software agents for collecting network traffic and threat simulators that perform attacks on network nodes from single sources or in a distributed environment. Researchers will be able to use the data collected in the infrastructure for cybersecurity analysis to create reliable IoT-based solutions needed to implement this technology in knowledge-intensive space systems production.
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Статья научная
The possibilities of creating an innovative educational and scientific center for monitoring forest resources in Siberia on the basis of the Department of Space Facilities and Technologies of the Reshetnev Siberian State University of Science and Technology are discussed, with the aim of training highly qualified engineering personnel and conducting promising scientific research in the field of monitoring, modeling, forecasting and management of forest resources. Methodological solutions and algorithms for threedimensional modeling of forest structure and dynamics based on laser scanning data, digital aerial and space photography are proposed. These methods contribute to operational monitoring and can significantly reduce the cost of monitoring the condition and use of forest resources over the vast territory of Siberia. Remote sensing data is presented in the form of a geotransformed database and digital photo map, compatible in formats with computer-aided design systems and with the main geographic information systems – ArcView, ArcINFO, MapINFO. The innovative monitoring center will be used for operational state control and monitoring of forest management, the state of forest lands, forest management and forest inventory, solving problems of ecology and environmental management, geoecology, formation of a forest resource inventory, aerospace methods for studying natural resources and territories, information technology. Solving these problems will allow for the training of highly qualified specialists. The center's specialists plan to create information technologies for remote sensing of natural objects with the aim of import substitution of foreign software products. The main scientific directions of the created center: development and research of methods for system analysis of large-scale multidimensional remote sensing data based on nonparametric decision-making algorithms and parallel computing technologies; testing hypotheses about the distributions of large-volume remote sensing data based on nonparametric nuclear-type pattern recognition algorithms; detection of compact groups of large-volume remote sensing data corresponding to unimodal fragments of the joint probability density of multivariate random variables.
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Статья научная
Academician Mikhail Fedorovich Reshetnev is one of the outstanding scientists, designers and production organizers who stood at the origins of the development of rocket and space technology in our country and made a significant contribution to domestic and world cosmonautics. 2024 marks the 100th anniversary of his birth and the 60th anniversary of the first launch of the Kosmos-3 launch vehicle (LV), created under his leadership in the Krasnoyarsk Territory. The article discusses the main stages of design, development work, flight design tests and the launch of mass production of the rocket. It is noted that the creation of the PH was carried out mainly at the production base of the Krasnoyarsk Machine-Building Plant (Krasmash). The most important events related to the organization of the OKB-1 branch, which was then transformed into an independent OKB, are described in chronological order. The role of M. F. Reshetnev’s personality is shown. Reshetnev in solving complex scientific, technical, organizational and production problems of mastering new technology in the Siberian region, remote from the rocket, space and scientific centers of the country. Information is provided on innovative technical solutions developed under the guidance of M. F. Reshetnev during the creation of the Kosmos-3 launch vehicle and its subsequent modification. It is noted that M. F. Reshetnev in his scientific and technical activities constantly received the support of S. P. Korolev and M. K. Yangel, successfully cooperated with the largest design organizations headed by V. P. Glushko, A. M. Isaev, V. G. Sergeev and other well-known leaders and specialists of the rocket and space industry.
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Inter-satellite optical communication link
Статья научная
A two-level system of data transmission in the optical range is considered between a low-orbit spacecraft located in a sun-synchronous orbit and a repeater satellite located in a geostationary orbit. This topic is rather relevant due to the fact that the rapid development of remote sensing satellites resulted in the increase of the amount of transmitted information, which in consequence introduced new requirements for communication systems. The increase of data transmission rate and severization of requirements for communication systems contributed to the development of one of the most promising areas of space communications, based on the information transmission via a laser channel, due to a high energy concentration and a much higher carrier frequency. The prospects for the application of optical communication systems are designated by lower power consumption, dimensional specifications and the mass of the transceiver equipment of the optical range (compared to radiofrequency range systems). The article describes the solution of application of optical communication link between a low-orbit spacecraft and a repeater satellite. The main factors that contribute to the attenuation in the process of signal propagation along the route are presented and analyzed. A model of a communication channel between a low-orbit spacecraft and a repeater satellite is provided for a visual image. Two different approaches of mutual guidance and tracking of laser terminals are described for using beacons and without ones. EDRS foreign system is considered as an analogue. The estimation of the main parameters of the communication link is given. The communication system considered in the article will allow for greater carrier capacity of the data transmission in the optical range between the low-orbit spacecraft and repeater satellite. The application of this system will allow solving problems, including in the interests of any departments and structures of the Ministry of Defense of the Russian Federation, for which the rate of obtaining information is one of the basic requirements for a satellite communication system. The tasks of precise targeting of receiving and transmitting devices arising as a result of narrow beam patterns can be solved with current technical means.
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Interaction of magnetic and dielectric subsystes in a bismuth nodymic ferrite-granate
Статья научная
Bismuth-substituted ferrite garnets possess magneto-optical (MO) properties and are used as spatial light modulators and indicators. The paper studies the influence of magnetic and electric fields on the structural characteristics of thin epitaxial films of bismuth-neodymium ferrite garnet (Bi: NIG) deposited on glass and gallium gadolinium garnet (GGG) substrates. Dynamic properties of polarization, relaxation in a magnetic and electric field are considered, which is an important task for getting a deep insight into the mechanisms of electromagnetic phenomena in solids. Dependence of the magnetostriction coefficient on the magnetic field and dependence of a relative change in the length of the film on the electric field at different temperatures are obtained. A change in the sign of magnetostriction constants with respect to temperature was found. The electric polarization in a periodically applied electric field of 400 V / cm with a frequency of 10 MHz is determined for various magnetic field orientations of 12 kOe and in the absence of a magnetic field. Anisotropy of polarization in a magnetic field and a functional dependence of the polarization relaxation on time are found. These materials can be used as sensors of the magnetic field in a spacecraft.
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Статья научная
Many strategically important sectors of the domestic industry are at the stage of transition to an investment approach to asset management. One of these industries is hydropower, where the current maintenance planning system needs new methods to deliver more efficient results. In general, the planning system for the main equipment (technical impact system) maintenance and repair can be formulated as a scheduling problem. The ant algorithm is of great interest from the point of view of solving the scheduling technical impact problem. Based on the specifics of planning, implementation and factors affecting the maintenance process, a modification of the ant algorithm is proposed. The mathematical description is a methodology for calculating parameters, basic elements of the graph, optimization criteria and constraints. A preparatory stage was also introduced into the solution algorithm, which determines the initial state of the equipment at the vertex K0. The functional model of the technical impact planning process presented in the article can be used to develop a software package within the framework of an innovative approach to asset management for hydropower companies.
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Статья научная
One of the most effective tools of remote sensing and visualization of underwater surfaces and objects are acoustic devices, in particular side-scan sonars (SSSs). Recently, largely due to the emergence of affordable devices, the geography and scope of application of SSSs has been significantly expanded. Meanwhile, despite certain progress achieved in terms of improving and minimizing the SSS hardware, the software used remains, in general, at a basic level, providing the operator mainly with a simple tool for visualizing benthic environments and data recording for further post-processing. Existing experience in SSS exploitation reveals that the key problem of interpreting acoustic images lies in the physical peculiarities of their acquisition. Arguably, attempts to implement methods of automated interpretation of optical images have no perspective. Hence, the objective of this paper is to provide a theoretical and practical background of SSS data interpretation and processing with the objective of further automation of this process. Taking into account the operating conditions of the SSS, in particular the vast areas of water areas - search zones, this problem is one of the key ones for SSS operators. The problem of automating data processing is directly related to the problem of interpreting remote sensing data, including satellite images, geometric distortion of images caused by the physical characteristics of the device and its operating environment, as well as referencing the obtained data to the satellite coordinate system.
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Статья научная
The relevance of the study is due to the need to improve the reliability and durability of steam turbines, which are widely used in the energy industry. One of the critical factors affecting the performance of turbines is the occurrence and development of cracks in the blades, which can lead to their destruction and emergency situations. This type of defects can significantly change the dynamic characteristics of a structure, reducing its life and increasing the likelihood of failure. Therefore, analyzing the effect of cracks on the vibration parameters and strength of blades is an important task for predicting their reliability and developing diagnostic methods. This article examines the effect of cracks on the dynamic and strength characteristics of steam turbine blades. The object of the study is a working wheel made of 304 stainless steel. The finite element model in the ANSYS Workbench environment was used for the analysis. The natural frequencies and vibration mode of the blades at different angular speeds of rotation, as well as the effect of cracks of various lengths on the dynamic characteristics of the structure, are investigated. The analysis results show that the presence of a defect leads to a decrease in natural oscillation frequencies, especially for low-frequency forms of bending vibrations. In addition, the effect of crack growth on the durability of the blades and the entire working wheel has been studied. It has been found that increasing the crack length significantly reduces the life of the blades, and the durability of the working wheel decreases more slowly due to the interaction of the blades with each other. The obtained results can be used in the development of methods for diagnosing and predicting the life of turbomachines, as well as to optimize their design in order to increase operational reliability.
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Статья научная
High-precision and reliable inspection of thermal deformations is necessary in terms of simulating the effects of space in the ground-based experimental processing of antennas and mirror systems of spacecrafts. Inspection of objects up to 1.5 m in size is considered in the paper. In practice, it can reach sizes up to 10 m. Requirements for thermal deformation are in range of 10–200 micrometers. The deformable surface is rough (Ra » λoptic). The measurement error, however, should not exceed ± 1 micron. The electronic speckle pattern interferometry (ESPI) method is the most suitable for solving this problem. The method allows to inspection objects with a randomly inhomogeneous surface. The method assumes that it is necessary to calculate the wave phase values from the recorded picture by the digital matrix. It is the phase that contains information about the deformation, and the spatial phase shift method is used to calculate it. One of the measuring systems based on this method is the measuring system PulsESPI (Carl Zeiss Optotechnik GmbH production, Germany). It has a high sensitivity which is about 50 nm. However, this measuring system is designed for single measurements. In this regard, an additional software module for processing and visualization the result of a series of several hundred measurements has been developed. The experimental test bench with a test object has been developed to research the metrological characteristics of the PulsESPI system in accordance with thermal deformations measurements (multiple determinations). The PulsESPI system and the Renishaw XL-80 interferometer introduced into register of measuring instrumentation of Russian Federation were located on different sides of the object 1.5 m in size. As a result of measuring the surface displacement measured by the Renishaw XL-80 interferometer and its corresponding point from the PulsESPI system deformation map are compared. Three types of tests were carried out at the developed bench. The root-mean-square deviation of single measurements was no more than ± 0.2 μm. Error was no more than ± 1 μm when the series of measurements was conducted in which a total strain of 200 μm was obtained. The results obtained suggest the possibility of using this system for high-precision inspection of thermal deformations of large objects.
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Статья научная
The object of the study is a cylindrical mesh shell without a regular structure covering, made of carbon fiber composite material. A distinctive feature of this class of structures is the intersection of families of annular and spiral ribs. Mesh shells are used as power elements of spacecraft, therefore, when designing them, the main re-quirements are a reduction in the mass of the structure, high strength and stiffness characteristics. The re-duction of the shell mass is achieved by varying and selecting the structural and geometric parameters of the ribs. The article considers a set of mesh cylindrical structures of fixed mass. The authors have developed and presented an algorithm for calculating the number of elements of a regular rib structure and calculating the values of geometric parameters of elements of rib families. Two approaches to the formation of rib sys-tems are considered: by changing the heights or thicknesses of the rib structure. A macro has been developed for modeling parametric discrete models of such rib structures in the An-sys Mechanical APD software package. When constructing discrete grid models, a one-dimensional two-node finite element BEAM4 was used. The model was rigidly attached at the nodes along the lower edge, a load was applied to the nodes of the upper edge. Two types of loading were considered. The “non-flight” mode was determined by the axial loading of the shell evenly distributed along the upper edge. Flight mode – additionally took into account the applied moment. The displacement and deformation fields were calculated numerically in the ANSYS finite element package. The article presents the results of a study of the effect of the density of the rib structure on the stability of mesh shells under static axial loading, natural frequencies and waveforms. It is shown that with increasing density, the rib structure becomes thinner. At the same time, the critical load decreases, the values of the natural frequencies of the shells decrease, and the number of waves in the forms increases. The influence of approaches to the modeling of rib structures on the results of numerical calculations is noted.
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Статья научная
We have considered the issues of ensuring the resistance of high-voltage solar battery (SB) of spacecraft to the effects of secondary arc discharges. Research in this area has been going on for more than 50 years, but the answer to all the questions has not yet been found. First of all, this is due to the complexity of the electrophysical processes occurring on the surface of the spacecraft in space and in laboratory conditions. The second reason is the random nature of secondary vacuum arc discharges, which requires the use of special test methods to confirm the effectiveness and reliability of selected design and technological solutions. Tests in conditions close to full-scale conditions do not allow us to solve this problem. We have given a retrospective review of publications on the physical features of secondary arcs arising on SB of spacecraft, the mechanisms of their initiation, experimental research and testing methods. We paid considerable attention to the issues of the occurrence of secondary arc discharges SB of the spacecraft in the conditions of ionospheric plasma and plasma generated by electric propulsion thrusters. We have shown that despite the large amount of accumulated data and knowledge, the transition from low-voltage SB to high-voltage SB remains a difficult scientific and technical problem, which requires additional research to solve. In addition, it is already necessary to start training personnel who possess a wide range of knowledge and are able to work on this topic. To do this, it seems advisable to organize sectoral research, as well as the allocation of targeted funds for the training of highly qualified specialists and their independent research. This approach will make it possible to solve the problem of creating high-voltage SB in the shortest possible time and prepare personnel for the development of this technology.
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Статья научная
The relevance of the work is explained by the significant problems of the modern aerospace industry, mechanical engineering, energy, mining, processing and other industries in the disposal of waste products made of composite materials and products based on composites of various functional purposes (carbon fiber, fiberglass, metalceramic and cast glass reinforced). The aim of the work is to increase the efficiency of processes for obtaining micron fractions of composite materials waste through the use of an upgraded roller crushershredder design. Computational and experimental studies have substantiated the possibility of increasing the efficiency of waste recycling of composite materials due to their gradual (step-by-step) disintegration. Based on analytical calculations and finite element analysis methods, a kinematic scheme, layout and design of an up-graded prefabricated roller crusher-shredder with working bodies (discs) in the form of an equiaxed contour – a Relo triangle – have been developed. The new design implements a more complex system of forces (compression, friction, alternating cyclic loads) compared to analogues, which makes it possible to increase the speed and productivity of the crushing process. The process of cutting the material using the “rotating scissors” mechanism is implemented between adjacent counter knives of the PK profile, which also contributes to more intensive grinding of the material (especially when processing lamellar or long fragments of waste). The original location and inconsistency of the contact points of the oncoming profiles, the gap between the discs during their rotation creates a rolling effect due to the reciprocating movement of the crushed material, which reduces the risk of jamming and increases the throughput of the grinding rolls and the intensity of the disintegration processes. In order to determine the best performance in terms of the size of the working bodies of the crusher, the gap between them when grinding materials with different sizes and properties, kinematic models were created to simulate the grinding processes and conduct a numerical experiment using finite element analysis methods. It is shown that due to the effective combina-tion of various fracture mechanisms (abrasion, crushing, cutting, alternating loads), the intensity of deformation processes and specific loads on the material increases, but the stresses on the working surfaces of the crusher vary in the range of 430–580 MPa, the safety margin of the working bodies increases to 0.43–0.65, which is a prerequisite for increasing the service life of the workers. grinding elements. The results of calculations using new methods and kinematic schemes show that the design of the upgraded prefabricated roller crusher with working bodies in the form of a Relo triangle has an increased resultant speed (by 30 %) and productivity is almost 2 times higher than the prototype with cylindrical rolls (with the same or comparable sizes of working bodies, kinematic parameters in terms of rotation speed and drive power). Design and technological preparation were carried out and a prototype of the installation for experimental studies was made, which confirmed a good agreement between the calculated and experimental data on the size of the gap, the speed and productivity of the crushing and crushing process.
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Laboratory separator of bulk materials
Статья научная
New materials for spacecraft radiation screens engineering require a fine classification of powder materials by particle size. The article concerns the construction of powder materials laboratory separator. This type of material separation is related to gravity methods. The Moseley laboratory separator serves as the prototype of the construction with table longitudinal shaking and diametrical vibrations by means of buffers during the separation process. The unbalanced oscillator yields deck separation surface harmonic vibrations in all directions. The unbalanced oscillator DC motor voltage control gradually alters the vibration frequency and supports finer separation of the material. A power pipe enables to conduct perpetual separation process. In prototype, in contrast, up to 100 g weight is processed for up to 5 minutes. To improve the materials fine and small classes separation efficiency, riffles are made on the separation surface, which determine the places of concentration of material particles. As a result of the conducted researches for elimination of the secondary circulation flows, a system of diametrical reefing is worked out: the riffle is approximately equal to the maximum particle size of the separated material and is equal to 0.2 mm in this construction; the distance between riffles is equal to 50 mm, the tilt angle is 80 degrees relative to the deck longitudinal side. The particle motion depends on the inclination angle of the separation surface. Large particles move upwards at angles of up to 5 degrees, and downwards at angles higher than 5 degrees. Vibration frequency and amplitude alteration, as well as adjusting the inclination angle of separation surface enables to move and adjust the speed of different properties and sizes of test material. The laboratory separator work is based on the physical effects, which enable to vary the location of the power pipe. This fact allows the construction to be adapted to a variety of specific conditions and expands the construction sphere. The separator construction is simple for production and operation, and can be quickly reconfigured if necessary. The separator portability allows it to be transported.
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Laser processing of titanium alloys to increase the strength of adhesive joint with cfrp
Статья научная
Titanium alloys are hard-to-bond materials due to the fact that a thin oxide film is always present on their surface, which prevents the formation of interatomic and intermolecular bonds between the adhesive and the substrate. In the load-bearing structures of spacecraft (SC), an adhesive bond between a titanium alloy and a composite material is often used. But the strength of such knots is relatively small compared to the mechanical connection. The purpose of this work is to increase the strength of the adhesive joint, due to laser processing of the working surface of the titanium alloy for gluing. Texturing of the surface of the tita-nium alloy OT-4 was carried out on an ytterbium pulsed fiber laser in 4 processing modes. The treated sur-face was glued with KMU-4 carbon fiber over an area of 300 mm2 using a VK-9 three-component adhesive. The adhesive strength test was carried out on a Eurotest T-50 tensile tester. The test showed that the strength of the laser-treated samples increased by more than 80% relative to the average value of mechan-ical grinding. The highest value of shear strength was shown by samples with laser processing No. 1 and No. 3. This is due to the greatest increase in the area of bonding of the surface, as well as the mechanical locking of the adhesive in the microrelief of the structure. The increase in shear strength caused by laser surface treatment is a mixed effect of increasing surface area, mechanically locking the adhesive, and changing the surface chemistry. The chemical composition of the surface structure under the influence of laser scanning is gradually transformed from Ti and Ti2O3 to crystalline TiO2. The nature of the destruc-tion of the adhesive joint in the samples with laser processing is predominantly cohesive, but samples with the destruction of the carbon fiber material were also observed, that is, the shear stress in the composite material exceeded the adhesive strength. The effect of pretreatment of the composite material on the strength of the adhesive joint was not considered in this work.
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