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MODERN RESEARCH ON MAGNETIC LUBRICANTS
Authors: A.N. BOLOTOV,
O.O. NOVIKOVA,
E.A. RATKEVICH,
Abstract: The article is devoted to the study of magnetic lubricants (ML). An analysis of the structure, composition and properties of ML is presented, including a dispersed phase consisting of ferromagnetic nanoparticles and a dispersion medium such as mineral oils or synthetic liquids. The features of the influence of a magnetic field on the rheology and efficiency of ML, as well as mechanisms for forming anti-wear and anti-friction properties, are considered. An overview of recent experimental studies demonstrating a significant increase in the effectiveness of ML compared to traditional oils is provided, and prospects for further improvement of these materials through optimization of their composition and manufacturing technology are analyzed. Conclusions are drawn about the considerable potential of ML for a wide range of industrial sectors, such as machinery construction, aviation and space exploration, emphasizing the importance of continuing scientific research in this direction.
Keywords: magnetic lubricants, ferromagnetic nanoparticles, dispersion medium, rheology of magnetic lubricants, tribology of magnetic lubricants, magnetic-liquid bearings.
MAGNETIC FLUID SEALING OF AN ELECTRIC MOTOR SHAFT, ADJUSTABLE IN TERMS OF MAINTAINED PRESSURE DIFFERENTIAL, FRICTION LOSSES, ROTATION FREQUENCY AND THERMAL MODE
Authors: A.M. VLASOV,
Yu.B. KAZAKOV
Abstract: The efficiency of magnetic fluid shaft sealing is affected by the pressure difference and external temperature, conditions and operating mode of the electric motor (start, braking, stopping, reversing, rotation speed and electrical load). Electromagnetic processes in an electric motor, through the action of the rotating magnetic flux of the windings, affect the flow rate of the magnetic fluid, the torque and friction losses in the magnetic fluid seal. It is advisable to regulate the properties of the magnetic fluid shaft seal according to the operating conditions of the electric motor. A design of an adjustable magnetic fluid seal is proposed and an algorithm for its regulation is developed, which allows for the adaptation of the magnetic fluid seal of the shaft to changes in the operating conditions of the electric motor. The possibility of changing the maximum retained pressure difference in an adjustable magnetic fluid seal has been experimentally confirmed.
Keywords: magnetic fluid shaft sealing, electric motor, regulation, pressure drop, friction losses, thermal conditions, rotation speed.
IMPROVING THE MECHANICAL AND TRIBOLOGICAL CHARACTERISTICS OF EPOXY COATINGS WITH THE INTRODUCTION OF GRAPHITE FILLER AND CURING IN A CONSTANT ELECTRIC FIELD
Authors: M.F. GALIKHANOV,
E.N. MOCHALOVA,
T.T. MUSAEV
Abstract: The effect of the curing conditions of epoxy composites based on epoxy resin
DER-331 and modified amine hardener L-20 and the introduction of a dispersed graphite filler on their mechanical and tribological properties is investigated. It has been experimentally shown that curing using an electric field leads to the orientation of polar groups and filler particles, which additionally increases hardness and reduces friction coefficients by 25%. Introduction of 4 wt. % graphite provides a significant reduction in the coefficient of friction and a slight hardening of the material, which improves its wear resistance. An integrated approach combining the choice of a matrix, the use of a filler and the application of a constant electric field during the curing process will increase the wear resistance of epoxy coatings, which will extend their service life and expand the scope of practical application.
Keywords: epoxy resin, modified amine hardener, graphite, polarization, coefficient of friction, strength, hardness.
ANALYSIS OF THE FRICTION PROPERTIES OF DIAMOND-CONTAINING CERAMICS AND DETERMINATION OF THEIR APPLICATIONS
Authors: O.O. NOVIKOVA,
V.V. NOVIKOV,
A.N. BOLOTOV
Abstract: The paper theoretically and experimentally studies the frictional properties of a composite material, which is a ceramic matrix of aluminum oxides, doped with micro-dispersed diamonds. The contact interaction and frictional characteristics of this material are considered under conditions of elastic contact of micro-irregularities in the process of steady-state wear and brittle fracture of surfaces in the high-pressure area. The results of tribotechnical tests confirmed the good antifrictional characteristics of the diamond-containing ceramic material under dry friction conditions, which is explained by the presence of graphite in the material, which acts as a solid lubricant. A detailed analysis of the influence of granulometric characteristics and diamond grain concentration on the microstrength, critical pressure, and friction coefficient of the studied surfaces was conducted. Recommendations are given on the practical application of parts made of diamond-containing ceramic material in tribo units of science-intensive equipment.
Keywords: microarc oxidation, diamond-containing ceramic material, solid lubricant material, antifriction properties, microstrength, friction, wear.
ON THE REGRESSION RELATIONSHIPS USED TO DESCRIBE THE FRICTIONAL INTERACTION OF ENGINEERING SURFACES
Authors: V.V. IZMAILOV,
A.F. GUSEV,
M.V. NOVOSELOVA
Abstract: Using the initial point contact of solids (ball – plane contact) as an example, the correspondence between well-known tribological linear relationships describing the frictional interaction of technical surfaces is analyzed: the specific friction force dependence on the actual contact pressure and the friction force dependence on the external normal load. It is noted, that the adhesive interaction of contacting bodies, which can be compared with the magnitude of the external normal force, has to be taken into account. It is shown that the linear dependence of the specific friction force on the actual contact pressure directly corresponds to the nonlinear dependence of the friction force on the external normal load. However, over a certain range of the latter's variation, this dependence is well approximated by a linear equation known as Coulomb's two-term friction law. A comparison of the experimental friction force measurements with their calculated values is provided, demonstrating good agreement for the tested metal friction pairs.
Keywords: friction force, specific friction force, Coulomb's friction law, contact adhesion.
ON THE FRICTIONAL CHARACTERISTICS OF THE LASER-DEPOSITED NICKEL ALLOY SURFACE
Authors: V.V. IZMAILOV,
L.E. AFANASIEVA,
M.V. NOVOSELOVA
Abstract: The frictional characteristics of powder laser cladding of a nickel alloy were studied, including friction force, friction coefficient, and specific friction force. Powder laser cladding was performed by sequentially depositing three layers using a multichannel laser. After cladding, the coating surface was further remelted using different laser radiation modes, varying the alloy crystallization conditions. As a result, a uniform microstructure formed in the surface layer of all samples, differing only in the size of the structural components. It was shown that varying the coating surface melting modes within the selected range does not significantly affect the frictional characteristics of the contact between the steel indenter and the coating surface.
Keywords: friction coefficient, specific friction force, powder laser cladding, multichannel laser, nickel alloys.
IMPROVEMENT OF THE INSTALLATION OF A SHAFT WITH A CONICAL SURFACE ON THE CENTERS OF THE MACHINE
Authors: A.P. ARKHAROV
Abstract: The relevance of the topic under study is noted. The analysis of known methods and means of technological equipment for the installation of workpieces in the form of shafts on metal-cutting machines is presented. The essence of the improved method and chuck for installing shafts containing a conical surface on the centers of the machine is disclosed. Their essential features are compared with similar well-known solutions. The technical result achieved by using the proposed improvement is reflected.
Keywords: shaft, installation, method, chuck, clamping elements, tapered surface, technological capabilities, thrust centers.
HYDRAULIC JUSTIFICATION OF THE PARAMETERS OF THE INCUBATION SYSTEM INSTALLED AT ABANDONED PEAT DEPOSITS
Authors: A.A. ANDRIANOVA,
А.L. YABLONEV
Abstract: Reclamation of depleted peat deposits is an important economic task. Modern reclamation methods generally involve flooding and irrigating the areas. Irrigated areas can be used for the reproduction of valuable fish species using incubation systems designed for use in flowing water. Corrugated PVC pipes are the most suitable for supply pipes. The experimental determination of critical velocities and critical Reynolds numbers, conducted in this study, will enable future hydraulic calculations for incubation systems.
Keywords: depleted peat deposit, flooding, stocking, incubation system, corrugated PVC pipe, critical velocity, critical Reynolds number.
MATHEMATICAL MODEL OF ACCELERATION OF A PIECE OF ROCK
IN THE ROTOR OF A CENTRIFUGAL CRUSHER
WITH A VERTICAL AXIS OF ROTATION
Authors: A.I. AFANASYEV,
V.V. ZUBOV,
D.I. SIMISINOV,
V.S. SHESTAKOV
Abstract: The paper considers the relationship between the kinematic parameters of the working process and the energy costs of rock destruction in the rotor of a centrifugal crusher. A model of the movement of a piece of rock in a horizontally positioned rotor is proposed. The model allows us to calculate the parameters of the acceleration process of a piece of rock, taking into account the physical and mechanical properties of the rock, the degree of crushing and the design parameters of the rotor. It has been established that the Coriolis force makes a significant contribution to the normal reaction of the blade to a piece of rock. It is shown that it is not advisable to increase the impact velocity of a piece of armor by increasing the angle of inclination of the blade to the radius, since this increases the normal reaction and, consequently, the wear rate.
Keywords: rock, particle kinematics, acceleration dynamics, friction and inertia forces, Coriolis Effect, specific energy consumption.
ON A NEW PROPERTY OF RECURRENT MOTIONS OF DYNAMIC SYSTEMS ON COMPACT MANIFOLDS
Authors: S.M. DZYUBA,
I.I. EMELYANOVA
Abstract: Based on the definitions of minimal set and recurrent motion introduced by J. Birkhoff at the beginning of the last century, a new sufficient condition for the recurrence of motions of dynamical systems on a topological compact manifold V is obtained. This condition gives a fairly complete picture of the structure of recurrent motion as a function of time on V and, thus, organically complements Birkhoff's classical definition.
One of the main results of this paper is that it leads to a new method of approximate recurrent movements. This method can be applied without fundamental changes to the construction of asymptotic recurrent solutions of nonautonomous systems of ordinary differential equations.
Keywords: topological compact manifold, dynamical systems, recurrent motions.
AUTOMATION OF RISK MANAGEMENT PROCESSES USING A TELEGRAM-BOT
Authors: N.G. MARILOV,
L.V. KOZYREVA,
E.I. MARILOVA
Abstract: This article defines an integrated approach to assessing professional risks, implemented as a Telegram bot. The approach synthesizes three complementary methods: a deterministic assessment based on the Special Assessment of Working Conditions (SAWC), probabilistic Monte Carlo modeling, and an uncertainty assessment based on the GUM guidelines. A pilot test of the solution demonstrated its effectiveness, resulting in increased assessment timeliness and increased employee engagement. A comparative analysis revealed that in 40 % of cases, the point estimates of the SAWC corresponded to the model's interval data, while in 15 %, they were underestimated. This approach is a direct extension of traditional methods, overcoming their limitations by comprehensively considering the probabilistic nature and uncertainty of the initial data, enabling a transition from reactive to preventive risk management.
Keywords: professional risks, risk assessment, Telegram bot, Monte Carlo method, GUM, SAWC, digitalization of occupational safety, risk management.
DEVELOPMENT OF A STABILIZATION ACTUATOR MODEL FOR AN UNMANNED AERIAL VEHICLE
Authors: V.A. SMIRNOV,
V.P. ORLOV
Abstract: The article focuses on the development of a stabilization actuator model for an unmanned aerial vehicle. The necessity of using adequate mathematical models of the unmanned aerial vehicle, which account for its aerodynamic specificities, is substantiated. The problem of roll angular rate stabilization under a step disturbance torque is investigated as an example. A series of experiments was conducted to assess the influence of the actuator time constant, the mismatch of its rate characteristics, and variations in sensor parameters. The simulation results, presented as transient processes, demonstrate that to ensure the reliability of the results, the dynamic actuator model within the stabilization loop must have a greater time delay than the real actuator. It is shown that even with a random variation in the time constants of the system components, it is possible to create a functional model of it.
Keywords: stabilization actuator, actuator modeling, unmanned aerial vehicle, roll angular rate, disturbance torque, transient processes, actuation rate, time constant, corrective devices, system stability.