Vol 24, No 1 (2022)

ARTICLES
CORROSION DAMAGE INFLUENCE ON RELIABILITY AND DURABILITY OF CYCLICALLY LOADED VALVE RODS OF THIN WALL SUBSURFACE PUMPS. MODELING AND CALCULATION
Moltsen S.N., Kravchenko A.V., Simonov Y.N.

Abstract

The issues of reliability and durability of the API thin-walled sucker rod pumps new for Russian Federation are considered. Here were reviewed real failures caused by corrosion fatigue of pump valve rod operating under cyclic loading in aggressive environment. A high set of mechanical properties as a satisfactory metallurgical quality cannot prevent fatigue failure, but only postpone it in time. Fatigue and its particular, even more dangerous form, corrosion fatigue, destroy structures in the most dangerous constructional places. Even in simple parts, the stresses in concentrators such as threads exceed more than five times the nominal stress level, which is away from the concentrator. The stress value is calculated both by the classical analytical method according to modified Inglis formula, and by modern methods of finite element analysis. At paper is presented a graphical diagram of the stress distribution. The maximum loaded microvolumes of the material are a tiny fraction of the total volume of parts. Corrosion fatigue, based on its corrosion nature, does not have an “dry” endurance limit due to growing corrosion damage in the form of pitting corrosion. Even small pits significantly increase the stress level at stress concentrators. The maximum stress of investigated pumps valve rods after corrosion increase for 29 % due to the formation of a simplified hemispherical pit at the root of thread. In reality, corrosion damage is irregular and appears to increase stress even more. Recommendations for the prevention of corrosion fatigue are given in the form of a list. They are actions of various levels of complexity, from practically not requiring additional costs to those requiring organizational development and subsequent maintenance.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):5-14
views
MODELING THE ENERGY INTENSITY OF PLASTIC DEFORMATION OF THE CUTTING SURFACES OF THE CUTTING WHEEL DURING ABRASIVE CUTTING OF PIPES
Levchenko E.A.

Abstract

The features of modeling the energy consumption of plastic deformation of the side cutting surfaces of the cutting wheel during abrasive cutting of pipes are considered. Abrasive cutting of materials, from the point of view of physical processes occurring in the surface layers of the cut workpieces, is one of the most high-temperature and highly plastic machining processes. The deformation process arising during cutting is characterized by the stressed state of the surface layer of the cut workpiece and can be characterized by the presence of both compressive and tensile stresses, the maximum value of which does not always take place on the surface, but shifts into the depth of the formed surface layer of the section of the part and leads to its change. It has been established that the causes of the stress state of the groove section are the inhomogeneity of plastic deformation and local heating of the metal of the surface layer, and in the presence of transformations, the difference in the volumes of the emerging structures. Depending on the cutting conditions, the stress state of the surface layer will be determined either by the dominant influence of one of these factors, or by their joint action. The observed non-uniform distribution of the stress state of the surface layer of the metal is explained by the action of two factors - mechanical (plastic deformation), which induces only compressive stresses, and thermal (heating of the surface layer), which is the cause of the formation of only tensile stresses. The results of the study of the regularities of the process, which determine the energy intensity of plastic deformation during abrasive cutting, are presented. The energy intensity of the process, in turn, has a significant impact on the course of the process, in particular, on the quality and accuracy of products. Analytical dependences of the energy consumption of the cutting process are presented, which subsequently make it possible to develop mathematical models for determining the components of the cutting force during abrasive cutting.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):15-20
views
DESIGNING A MULTI-LAYER TiAlN-TiN-TiAlN COATING WITH HIGH TRIBOLOGICAL PROPERTIES
Soshina T.O., Plysnina V.A., Soshina O.I.

Abstract

One-component TiN and TiAlN coatings obtained by the PVD method have been studied. Microstructural analysis of coatings was carried out using an Ultra 55 microscope, structural analysis was carried out on a DRON-4 diffractometer, functional properties were studied on a Micro-combi tester and an AE-5 tribological setup according to the “finger-disk” scheme. Ion etching and microstructural analysis of the multilayer TiAlN - TiN - TiAlN coating was carried out on a Hitachi IM4000 setup. The physicomechanical and tribological properties of one-component coatings are determined depending on their phase composition and structural characteristics. The optimal phase composition of the TiAlN layer and the TiN layer, at which a high microhardness, resistance of the coating to deformations, and a low coefficient of friction are formed, have been revealed. So for the TiAlN layer, the optimal composition is to achieve the maximum volume fraction of the h-Ti3Al2N2 phase, and for the TiN layer, the optimal composition is to achieve the largest volume fraction of the c-TiN phase. The established dependences of the functional properties of TiN and TiAlN coatings on their phase composition, microstructure parameters served as the basis for designing a multilayer TiAlN - TiN - TiAlN coating. The alternating layers of TiAlN and TiN have optimal phase and structural characteristics and a set of high performance characteristics. Industrial tests of valves rods reinforced with multilayer TiAlN - TiN - TiAlN coatings were carried out under conditions of contact load, temperature and exposure to reagents of the working medium. The test results showed an increase in the service life of rods hardened by a multilayer TiAlN - TiN - TiAlN coating in comparison with unhardened ones by 3 ... 3.5 times.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):21-27
views
DEVELOPMENT OF A METHODOLOGY FOR THE DESIGN OF MEMBRANE PRESSURE SENSORS
Andreev A.I., Zhukov A.V., Yakovishin A.S.

Abstract

One of the primary measuring instruments is a variety of pressure transmitters and transducers. Pressure is one of the most important parameters controlled in the technological processes of almost all sectors of the economy: enterprises of the oil-producing and processing complex, modern energy, including nuclear power, mechanical engineering, housing and communal services and other industries. In all these cases, pressure measurement with higher accuracy increases the reliability of the measured results. The demand for pressure measuring devices by enterprises of the developing industry is constantly growing and at the same time requires the development of their functionality, as well as an increase in accuracy. Pressure transducers are one of the most common types of measuring equipment; they are used to register the pressure of gas and liquid media and are used as one of the most important parameters for conducting technological processes. The article describes in detail the calculation of the main elements of a membrane-type pressure sensor, namely, the calculation of the elastic, strength characteristics of the membrane is described in detail. A method for calculating the deformations of a circular plate of variable thickness is provided. A new approach was taken in the design of the membrane. The calculation of the pressure sensor is based on the received technical assignment for the manufacture of a sensor designed to operate under certain conditions. This is due to the fact that it is quite difficult to meet all the requirements for the membrane material, therefore the choice of the most suitable material depends on the requirements for the sensor. Often, the choice is associated with certain difficulties, since few materials at the same time have sufficient plasticity and high strength and elastic characteristics. When choosing a diaphragm material, one has to confine himself to satisfying only the most important requirements.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):28-34
views
INVESTIGATION OF THE STRUCTURE AND PROPERTIES OF NON-METALLIC INCLUSIONS IN STEELS
Lomaeva T.V., Kugultinov S.D., Popov I.V., Svirschev V.I.

Abstract

Abstract In the article, based on the analysis of the results of experimental studies of the dependence of the cutting temperature and transverse shrinkage of the chips on the cutting speed, a method is given for assigning the cutting speed during rough turning and boring of large-sized parts of rocket technology from titanium alloy VT6, taking into account the provision of safe processing conditions based on regulating the amount of shrinkage of the chips. Unlike most structural materials, chip shrinkage in titanium alloys can be “negative”. That is, thinning of the shavings can occur. In some cases, this can be dangerous, since the formation of fine chips and, moreover, dust in the process of chip formation leads to its ignition with intense combustion. One of the main factors affecting the productivity of machining is the cutting speed, the higher the speed, the higher the productivity. However, when processing large-sized parts of rocket technology, the enterprise currently uses metal-cutting equipment that does not have a cooling system. Thus, in order to avoid the formation of "negative" chips and their ignition, it is necessary to carefully select the cutting conditions. As a result of the research, it was found that, depending on the assigned cutting speed, it is necessary to select the feed of the cutting tool in such a way that the thickness of the resulting chips, taking into account the amount of shrinkage of the chips, would be greater than 0.07 mm. To achieve the required roughness of the machined surface, in the case of an increase in the feed of the cutting tool, it is necessary to geometrically select the value of the rounding radius at the tip of the cutter.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):35-40
views
THE METHOD OF INFRARED THERMOGRAPHY FOR DETECTING A HIDDEN DEFECT IN THE AVIATION STRUCTURE OF POLYMER COMPOSITES
Kornilov G.A.

Abstract

The possibility of using the method of infrared thermography for detecting a hidden defect in an aircraft structure made of polymer composite materials (PCM) is considered. The relevance of the problems discussed in the article is due to the fact that various sources of continuous thermal loading with subsequent poly-frame processing of thermograms were mainly used to identify a hidden defect, since the high labor intensity of obtaining the result and high requirements to the level of personnel training constrained their practical application. Given that the effectiveness of thermographic nondestructive testing of a structure depends on the nature of the thermal effect on the sample and the procedure for processing thermograms, both factors were comprehensively investigated in this work. The peculiarity of the developed technique of infrared thermography to detect a hidden defect in a composite structure is the combined use of a three-pulse source of thermal loading, which made it possible to vary the parameters of thermal influence, and two-dimensional mono-frame processing of thermograms. An element of an aircraft structure with open cavities of a certain depth was used as an experimental sample for testing the method for determining the defect boundary by the thickness of a sample of PCM products. Based on the test results, a rational mode of thermal loading of the sample during its irradiation was established and an effective procedure for converting thermograms to detect a defect in the structure was determined, while the application of the developed technique is feasible at the operator level. The work, in terms of its content and test results, is of great practical importance, since it will make it possible to apply the developed method of active thermal nondestructive testing of PCM products under natural conditions.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):41-48
views
ANALYSIS OF THE INFLUENCE OF A MULTI-LAYER PROTECTIVE COATING ON THE DEFORMATION AND OPTICAL CHARACTERISTICS OF A PANDA TYPE FIBER
Lesnikova Y.I.

Abstract

The paper investigates a polarization-maintaining single-mode optical Panda type fiber with a quartz diameter of 80 microns, covered with a two-layer polymer protective coating (PC) with a diameter of 167 microns, which is used to manufacture the sensitive loop of a fiber-optic gyroscope. An intermediate test of the waveguide after fabrication is simulated: a fiber with a tension force of 0.2 N is wound in one row on an aluminum coil and subjected to thermal cycling according to a given law in the operating temperature range °C. Within the framework of the work, 7 variants of the ratios of the internal and external PC were considered while maintaining the total fiber diameter, taking into account the heterogeneous properties of structural elements, the viscoelastic properties of the PC materials and the contact interaction of the fiber with the coil without taking into account the friction on the mating surfaces. The considered temperature range partially includes relaxation transitions in both PC layers, which leads to the appearance of creep deformation and changes in many physical and mechanical characteristics of the material. The behavior of the PC materials is described by the theory of linear viscoelasticity by means of the Prony model; to take into account the effect of temperature on the properties of the PC materials, the temperature-time analogy described by the Williams-Landell-Ferry equation is used. As a result of numerical experiments, dependences are obtained that describe the evolution of the stress-strain state in the fiber, the maximum contact pressure at the interface, and the change in the refractive index in the light-conducting core. A change in temperature during a thermal cycle affects the stress-strain state (SSS) of the entire fiber and the light-conducting core for all the considered ratios of the PC. With an increase in the percentage of the inner layer, a more non-linear character of deformation behavior is observed. Relaxation transitions in materials affect not only the stress-strain state of the system, but also the contact pressure, which is associated with a continuous change in the contact interaction area under the influence of temperature. It has been found that the optimal thickness of the internal memory is in the range from 30 to 70% of the total thickness of the memory. An additional study of the effect of the thickness on the waveguide near the standard ratio of the thicknesses of the PC is required.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):49-61
views
INFLUENCE OF BISMUTH ON CORROSION-ELECTROCHEMICAL BEHAVIOR OF ALUMINUM ALLOY Al5Fe10Si, IN THE MEDIUM OF ELECTROLYTE NaCl
Ganiev I.N., Nurov N.R., Yakubov U.S., Boturov K.

Abstract

The fight against corrosion of metals is the most important task of modern technology. One of the methods of protection against corrosion of underground utilities and equipment is the use of anodic protection using protectors. It is possible to use aluminum alloys with a high negative potential as an anode material. The anodic behavior of the bismuth-doped aluminum alloy Al5Fe10Si in the NaCl electrolyte medium was studied using the potentiostatic method at a potential sweep rate of 2 mV/s. The dependence of the change in the free corrosion potential on the time of the initial alloy Al5Fe10Si and alloys with bismuth show a potential shift towards the positive region. At the same time, the potential for free corrosion of an alloy with 1.0 wt% bismuth has a more positive value compared to the initial alloy. It is noted that an increase in the concentration of bismuth leads to a shift in the potential of free corrosion to the region of positive values. Additives of the alloying component (bismuth) to the Al5Fe10Si alloy in the electrolyte media 0.03; 0.3 and 3.0 % NaCl shifts the corrosion and pitting potentials of alloys to a positive range of values. In this case, the potential of repassivation also shifts to the positive region, which indicates an improvement in the passivability of the formed pitting corrosion foci in neutral media. It is shown that with an increase in the chloride ion concentration in the NaCl electrolyte, mixing in the negative region of the values of the potentials of free corrosion, pitting formation and alloys repassivation is observed. The corrosion rate of alloys, regardless of their composition, increases with an increase in the concentration of chloride ion. Bismuth additives reduce the corrosion rate of the initial alloy by 30-40%. Comparison of the electrochemical potentials of the studied alloys shows the possibility of using them as a protector for corrosion protection of steel structures and products.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):62-69
views
INVESTIGATION OF THE STRUCTURE AND DEFECTIVENESS OF TITANIUM ALLOYS DURING SURFACING
Homutinin I.S., Akulova S.N., Myshkina A.V., Krivonosova E.A., Lyamin Y.V.

Abstract

This paper presents the results of a study of the main regularities in the formation of the structure and properties of the heat-resistant titanium alloy VT-20 of the Ti-Al-V-Mo-Zr system in the repair technologies of argon-arc and laser powder surfacing. A significant disadvantage of recovery surfacing technologies is some structural features of the formation of the deposited material, in particular, the likelihood of non-fusion both along the border with the base metal and between the deposited layers, unfavorable structure, anisotropy, and, as a result, a decrease in mechanical properties. Laser powder surfacing was carried out on an MLS FL 040 installation based on a fiber-optic diode laser. Argon-arc surfacing was carried out on standard equipment. Structural studies of the deposited material, fusion zones between layers were carried out using light microscopy, quantitative metallographic analysis and tests of strength properties were carried out. The deposited metal microstructure consists of a lamellar α-phase, which is typical for pseudo-α-alloys with very low β-stabilization coefficients, which include the VT-20 alloy. The level of defectiveness of the deposited material, the morphology of the structure of the deposited layers have been studied. It has been established that the structure of the material deposited by laser technology has a significantly lower level of defectiveness of surfacings: no pores and cracks have been identified, and non-fusion areas are insignificant in length. It is shown that laser powder surfacing contributes to the refinement of the structure of the deposited titanium alloy, increasing the fineness of the α-phase plates, which is accompanied by an increase in microhardness to an average level of 250 HV. The technology of laser powder surfacing is proposed as the main repair technology for selected products made of titanium alloys.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):70-78
views
TESTING OF COMPUTER PROGRAMS USED IN MODELING BY THE DISCRETE ELEMENTS METHOD
Lobovikov D.V., Kharchenko A.V., Matygullina E.V.

Abstract

Discrete element method (DEM) modeling is used to study the dynamics of bulk materials. To verify the software implementation of the method, as well as to choose the integration time step, reliable test problems are required. This article presents a test analytical solution obtained in the framework of impact theory. Variants of collision of two spherical particles with sliding and rotation are considered. For the analytical solution, the hypotheses were adopted that the elastic deformation upon impact is close to zero, there is no plastic deformation, the loss of normal velocity upon impact is described by the recovery coefficient, and gravity is not taken into account. The initial velocity of particles is known. Solutions are obtained for the case of identical particles, as well as for particles of different diameters. The analytical solution is used to verify the own software implementation of the DEM method. A series of computational experiments was carried out with the choice of different parameters of the colliding particles and the parameters of the method. The article presents graphs of comparison of the tangential, normal speed of particles and the speed of rotation of the particle after the collision for the analytical and numerical solutions. It is shown that after the impact these parameters have a qualitative and quantitative similarity. To study the convergence of the method and to determine the optimal computational time step, an additional series of computational experiments was carried out. As a parameter characterizing the accuracy of calculations, the modulus of the speed of movement of the part after the impact was chosen. The convergence of the implementation of the method with decreasing computational time step is shown. Based on these data, you can choose the optimal time step for calculations.
Bulletin PNRPU. Mechanical engineering, materials science. 2022;24(1):79-86
views

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies