Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-399-404
V. Lugovoi
The paper presents a comparative theoretical analysis of the movements of the curved rods of various curvature forms, which can be applied as tools for ultrasonic treatment of holes in fragile materials. It has been shown that the traditional processing of holes by an ultrasonic method is based on the use of straight rods, in which the amplitudes of displacements on the working – free end corresponds to the value of displacements at the point of its attachment to the ultrasonic oscillation concentrator. Supplementing the configuration of a straight rod with a curvilinear shape in the form of a circular arc or a spiral twisted by one turn will allow obtaining additional displacements caused by the elastic properties of a section with a curved shape. The paper considers several calculated schemes of a curvilinear rod bounded by angles j equal to p/2, p and 2p, fferent direction of the external force action. The obtained results have shown that an increase in the circular arc angle leads to a corresponding increase in the elastic displacement index of the rod free end. In this case, the total displacements of the rod free end will be made from displacements caused by vibrations of the acoustic system and the displacements of a curved thin rod from an external force. Calculations have established that the magnitude of the elastic displacements of curved rods is influenced by the shape and magnitude of the angle, the direction of the external force, the radius of curvature, the rigidity of the cross section. The considered schemes of thin rods with curvilinear sections can find practical application in ultrasonic oscillatory systems for processing small-diameter holes in fragile materials. This increases the intensity of tool oscillations and improves the process performance.
{"title":"Theoretical Analysis of Thin Curved Rod Displacements V. P. Lugovoi1)","authors":"V. Lugovoi","doi":"10.21122/2227-1031-2021-20-5-399-404","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-399-404","url":null,"abstract":"The paper presents a comparative theoretical analysis of the movements of the curved rods of various curvature forms, which can be applied as tools for ultrasonic treatment of holes in fragile materials. It has been shown that the traditional processing of holes by an ultrasonic method is based on the use of straight rods, in which the amplitudes of displacements on the working – free end corresponds to the value of displacements at the point of its attachment to the ultrasonic oscillation concentrator. Supplementing the configuration of a straight rod with a curvilinear shape in the form of a circular arc or a spiral twisted by one turn will allow obtaining additional displacements caused by the elastic properties of a section with a curved shape. The paper considers several calculated schemes of a curvilinear rod bounded by angles j equal to p/2, p and 2p, fferent direction of the external force action. The obtained results have shown that an increase in the circular arc angle leads to a corresponding increase in the elastic displacement index of the rod free end. In this case, the total displacements of the rod free end will be made from displacements caused by vibrations of the acoustic system and the displacements of a curved thin rod from an external force. Calculations have established that the magnitude of the elastic displacements of curved rods is influenced by the shape and magnitude of the angle, the direction of the external force, the radius of curvature, the rigidity of the cross section. The considered schemes of thin rods with curvilinear sections can find practical application in ultrasonic oscillatory systems for processing small-diameter holes in fragile materials. This increases the intensity of tool oscillations and improves the process performance.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"84 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72731426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-369-374
V. Okovity, F. Panteleenko, V. V. Okovity, V. Astashinsky
The paper presents studies on the optimization of the process of applying coatings from cermet powders with different solid phase contents by plasma spraying in air to restore and harden parts of machines and mechanisms operating under adverse conditions. Such conditions are usually created in heavily loaded tribojoints when the mechanisms operate at a low speed of relative movement of surfaces during friction. At the same time, the destruction of the working surfaces is mainly due to the process of microcontact setting and subsequent detachment of the formed particles at their contact points. The application of special protective coatings with the required properties is possible with the manufacture of high-quality starting powder materials and optimization of the technology for their application. Such powders and powder compositions can be obtained by the method of agglomeration of a fine powder mixture with its subsequent high-temperature sintering. To identify the hardening mechanism of composite coatings made of cermet by gas-thermal spraying, important stages are the optimization of the deposition process parameters and the study of the properties of plasma coatings obtained in this case. When optimizing the technological parameters of plasma spraying of coatings, the utilization rate of the sprayed powder material has been taken into account as the main indicator of the process efficiency, the structure of the obtained layers, and the morphology of individual particles deposited on the polished surface. The paper provides data on the structural elements of sprayed materials for wear-resistant coatings obtained by plasma spraying at optimal conditions. Taking into account the processes that occur during the wear of tribological conjugations, the data indicate the existing prerequisites for the wear resistance of the studied composite coatings made of metal ceramics. Special wear-resistant coatings made of materials with a soft matrix hardened by solid inclusions Al2O3–TiO2–Ni–Cr–Al–Y are widely used in various industries. Based on the detailed analysis of the features of cermet plasma coatings, it can be stated that such powder compositions (complex oxides-metal component) are often used as wear-resistant plasma coatings. The research results can be taken into account in cases of application of wear-resistant plasma coatings made of metal-ceramics and compositions based on them, containing solid phases in the form of oxides, as well as the manufacture of a whole range of parts operating under conditions of intense wear.
{"title":"Optimization of Coating Process from Cermet Powders by Plasma Spraying in Air","authors":"V. Okovity, F. Panteleenko, V. V. Okovity, V. Astashinsky","doi":"10.21122/2227-1031-2021-20-5-369-374","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-369-374","url":null,"abstract":"The paper presents studies on the optimization of the process of applying coatings from cermet powders with different solid phase contents by plasma spraying in air to restore and harden parts of machines and mechanisms operating under adverse conditions. Such conditions are usually created in heavily loaded tribojoints when the mechanisms operate at a low speed of relative movement of surfaces during friction. At the same time, the destruction of the working surfaces is mainly due to the process of microcontact setting and subsequent detachment of the formed particles at their contact points. The application of special protective coatings with the required properties is possible with the manufacture of high-quality starting powder materials and optimization of the technology for their application. Such powders and powder compositions can be obtained by the method of agglomeration of a fine powder mixture with its subsequent high-temperature sintering. To identify the hardening mechanism of composite coatings made of cermet by gas-thermal spraying, important stages are the optimization of the deposition process parameters and the study of the properties of plasma coatings obtained in this case. When optimizing the technological parameters of plasma spraying of coatings, the utilization rate of the sprayed powder material has been taken into account as the main indicator of the process efficiency, the structure of the obtained layers, and the morphology of individual particles deposited on the polished surface. The paper provides data on the structural elements of sprayed materials for wear-resistant coatings obtained by plasma spraying at optimal conditions. Taking into account the processes that occur during the wear of tribological conjugations, the data indicate the existing prerequisites for the wear resistance of the studied composite coatings made of metal ceramics. Special wear-resistant coatings made of materials with a soft matrix hardened by solid inclusions Al2O3–TiO2–Ni–Cr–Al–Y are widely used in various industries. Based on the detailed analysis of the features of cermet plasma coatings, it can be stated that such powder compositions (complex oxides-metal component) are often used as wear-resistant plasma coatings. The research results can be taken into account in cases of application of wear-resistant plasma coatings made of metal-ceramics and compositions based on them, containing solid phases in the form of oxides, as well as the manufacture of a whole range of parts operating under conditions of intense wear.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"57 10 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77602703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-375-382
V. Sheleg, M. Min, M. Belotserkovsky
The process of obtaining aerated (filled with air bubbles) polymer coatings has been developed and investigated by the method of flame spraying with an assessment of their ability to damp vibrations. A technology for the controlled formation of aerated polymer coatings has been developed while using the capabilities of the ОИМ (OIM) 050 polymer thermal atomizer design which consists in providing a concurrent air flow between the flame torch and the jet of powder material. The experiments have been carried out with such thermoplastic polymers as polyethylene terephthalate, high pressure polyethylene, ultra high molecular weight polyethylene, polyamide. It has been found that the aeration coefficient grows almost in direct proportion with an increase in the amount of air in the concurrent flow for all investigated polymer coatings. It is noted that the aeration process is influenced by the rheological properties of liquid polymers, or rather, the value of the polymer melt flow rate. The limiting values of air in the concurrent flow have been determined, which make it possible not to reduce the adhesion of polymer coatings to steel substrates by less than 6 MPa and not to decrease their hardness by more than 25–30 %. Studies of the damping properties of samples with polymer coatings have been carried out on a stand, the kinematic diagram of which is based on loading the free end of a cantilever sample, abrupt removal of the load and registration of free damped oscillations by an induction-type contactless sensor connected to a computer. It is shown that the use of aeration when forming noise-absorbing coatings on steel samples can increase their logarithmic damping decrement by 18–26 %.
{"title":"Production Technology and Damping Properties of Aerated Polymer Coatings","authors":"V. Sheleg, M. Min, M. Belotserkovsky","doi":"10.21122/2227-1031-2021-20-5-375-382","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-375-382","url":null,"abstract":"The process of obtaining aerated (filled with air bubbles) polymer coatings has been developed and investigated by the method of flame spraying with an assessment of their ability to damp vibrations. A technology for the controlled formation of aerated polymer coatings has been developed while using the capabilities of the ОИМ (OIM) 050 polymer thermal atomizer design which consists in providing a concurrent air flow between the flame torch and the jet of powder material. The experiments have been carried out with such thermoplastic polymers as polyethylene terephthalate, high pressure polyethylene, ultra high molecular weight polyethylene, polyamide. It has been found that the aeration coefficient grows almost in direct proportion with an increase in the amount of air in the concurrent flow for all investigated polymer coatings. It is noted that the aeration process is influenced by the rheological properties of liquid polymers, or rather, the value of the polymer melt flow rate. The limiting values of air in the concurrent flow have been determined, which make it possible not to reduce the adhesion of polymer coatings to steel substrates by less than 6 MPa and not to decrease their hardness by more than 25–30 %. Studies of the damping properties of samples with polymer coatings have been carried out on a stand, the kinematic diagram of which is based on loading the free end of a cantilever sample, abrupt removal of the load and registration of free damped oscillations by an induction-type contactless sensor connected to a computer. It is shown that the use of aeration when forming noise-absorbing coatings on steel samples can increase their logarithmic damping decrement by 18–26 %.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"216 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91387721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-445-448
A. Ilyin, A. Terentiev, F. Arslanov
The purpose of this study is to develop a circuit for an automobile air conditioner, which will reduce the consumption of power developed by the engine. This paper proposes the design of an automobile absorption air conditioner. A description of the principle of operation of an automobile absorption air conditioner operating on a cycle of a one-stage absorption refrigeration machine has been given in the paper. It consists of a stripper (generator), a condenser, an absorber, an evaporator. Lithium bromide (LiBr) solution has been used as an absorbent, which has a low boiling point, is non-toxic and safe. 3D-models of the absorber and generator of an automobile absorption air conditioner has been developed in the course of the research. The absorber is designed to form a weak absorbent solution. This solution is supplied to the generator heat exchanger using a liquid pump. There it is heated by the exhaust gases to the boiling point. The solution evaporates and water vapor enters the condenser (evaporator). In the generator, the solution is concentrated from 52 to 60 %. After that, water vapor is supplied to the absorber from the condenser, and a concentrated absorbent solution is supplied from the generator. It should be noted that the generator is a key element of an automobile absorption air conditioning system. Inside it is a strong LiBr solution that feeds the absorber. The design of the air conditioning system does not provide for the use of a compressor and allows to reduce the power loss of the power plant to the drive of the liquid pump. According to calculations, the pump drive power was 0.17 kW. For comparison, the compressor of a modern car air conditioner consumes 7–11 kW. An absorption car air conditioner provides the following advantages: additional engine cooling, environmental friendliness, fuel economy, efficient use of the heat of vehicle exhaust gases. A distinctive feature of this design is that it is proposed to use the heat of the exhaust gases for the process of heating the absorbent. This design can fully compete with the existing modern car air conditioners.
{"title":"Automobile Absorption Conditioner","authors":"A. Ilyin, A. Terentiev, F. Arslanov","doi":"10.21122/2227-1031-2021-20-5-445-448","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-445-448","url":null,"abstract":"The purpose of this study is to develop a circuit for an automobile air conditioner, which will reduce the consumption of power developed by the engine. This paper proposes the design of an automobile absorption air conditioner. A description of the principle of operation of an automobile absorption air conditioner operating on a cycle of a one-stage absorption refrigeration machine has been given in the paper. It consists of a stripper (generator), a condenser, an absorber, an evaporator. Lithium bromide (LiBr) solution has been used as an absorbent, which has a low boiling point, is non-toxic and safe. 3D-models of the absorber and generator of an automobile absorption air conditioner has been developed in the course of the research. The absorber is designed to form a weak absorbent solution. This solution is supplied to the generator heat exchanger using a liquid pump. There it is heated by the exhaust gases to the boiling point. The solution evaporates and water vapor enters the condenser (evaporator). In the generator, the solution is concentrated from 52 to 60 %. After that, water vapor is supplied to the absorber from the condenser, and a concentrated absorbent solution is supplied from the generator. It should be noted that the generator is a key element of an automobile absorption air conditioning system. Inside it is a strong LiBr solution that feeds the absorber. The design of the air conditioning system does not provide for the use of a compressor and allows to reduce the power loss of the power plant to the drive of the liquid pump. According to calculations, the pump drive power was 0.17 kW. For comparison, the compressor of a modern car air conditioner consumes 7–11 kW. An absorption car air conditioner provides the following advantages: additional engine cooling, environmental friendliness, fuel economy, efficient use of the heat of vehicle exhaust gases. A distinctive feature of this design is that it is proposed to use the heat of the exhaust gases for the process of heating the absorbent. This design can fully compete with the existing modern car air conditioners.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"16 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81749439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-390-398
A. Gorbunov, O. Devoino, V. A. Gorbunova, O. K. Yatskevitch, V. Koval’
Over the past few years, a group of new processes was developed for high-temperature, including plasma electric arc spraying (at ambient pressure) and spheroidizing of some ceramic and metal powder materials with the use of gaseous hydrocarbons in the heat carriers as well as with feeding of organic additions into a high-temperature jet, in particular, polymeric ones, to control porosity of sprayed metallic functional coatings. The paper considers the possibility to modify such technological processes by introducing solid fuel additions of a polymer type into the operating fluid of an apparatus for gasthermal (plasma or other) treatment, which provides melting of metal or oxide powders. For this, with the help of thermodynamic analysis, the processes have been evaluated at temperatures (300–3000) K for the set of such reacting five component systems as C–H–O–N–Me (at ambient pressure 0.101 MPa) with five variants of Ме – aluminum, titanium, chrome, copper, nickel. This makes it possible to consider these systems as simulants for potential technologies for the treatment of oxide powders (Al2O3, TiO2, Cr2O3) as well as metallic ones (Cu, Ni and their alloys). In order to obtain high exothermic contribution to the heating of powders, the combination “air + polymeric addition (polyethylene) of LDPE grade” was chosen as mixed heat carrier (operating fluid) for the basic version of simulated process. During the analysis of equilibria for the considered multicomponent systems (17 variants), a set of following parameters has been used to characterize the energy intensity of the target powder heating process: the equivalence ratio for reacting mixture and its adiabatic temperature; the energy efficiency of material heating with and without taking into account the effect of fuel addition; specific energy consumption for the powder melting; autothermicity degree of the process during the combined heating (electrothermal heating by the arc of plasma torch and heat flux from the “air + solid fuel additions” mixture) of refractory powders. As a result of the assessment, the preferred (from thermodynamic standpoint) regimes of the considered processes have been found and the possibility to realize an energy-efficient heating of these oxide and metal materials (without oxidation of the latter to CuOx, NiO) with a reduced part of the electric channel of energy transfer, resulted from the carrying out of appreciable effect of the fuel-initiated mechanism of heating in the analyzed C–H–O–N–Mesystems, has been shown in the paper.
{"title":"Thermodynamic Estimation of the Parameters for the C–H–O–N–Me-Systems as Operating Fluid Simulants for New Processes of Powder Thermal Spraying and Spheroidizing","authors":"A. Gorbunov, O. Devoino, V. A. Gorbunova, O. K. Yatskevitch, V. Koval’","doi":"10.21122/2227-1031-2021-20-5-390-398","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-390-398","url":null,"abstract":"Over the past few years, a group of new processes was developed for high-temperature, including plasma electric arc spraying (at ambient pressure) and spheroidizing of some ceramic and metal powder materials with the use of gaseous hydrocarbons in the heat carriers as well as with feeding of organic additions into a high-temperature jet, in particular, polymeric ones, to control porosity of sprayed metallic functional coatings. The paper considers the possibility to modify such technological processes by introducing solid fuel additions of a polymer type into the operating fluid of an apparatus for gasthermal (plasma or other) treatment, which provides melting of metal or oxide powders. For this, with the help of thermodynamic analysis, the processes have been evaluated at temperatures (300–3000) K for the set of such reacting five component systems as C–H–O–N–Me (at ambient pressure 0.101 MPa) with five variants of Ме – aluminum, titanium, chrome, copper, nickel. This makes it possible to consider these systems as simulants for potential technologies for the treatment of oxide powders (Al2O3, TiO2, Cr2O3) as well as metallic ones (Cu, Ni and their alloys). In order to obtain high exothermic contribution to the heating of powders, the combination “air + polymeric addition (polyethylene) of LDPE grade” was chosen as mixed heat carrier (operating fluid) for the basic version of simulated process. During the analysis of equilibria for the considered multicomponent systems (17 variants), a set of following parameters has been used to characterize the energy intensity of the target powder heating process: the equivalence ratio for reacting mixture and its adiabatic temperature; the energy efficiency of material heating with and without taking into account the effect of fuel addition; specific energy consumption for the powder melting; autothermicity degree of the process during the combined heating (electrothermal heating by the arc of plasma torch and heat flux from the “air + solid fuel additions” mixture) of refractory powders. As a result of the assessment, the preferred (from thermodynamic standpoint) regimes of the considered processes have been found and the possibility to realize an energy-efficient heating of these oxide and metal materials (without oxidation of the latter to CuOx, NiO) with a reduced part of the electric channel of energy transfer, resulted from the carrying out of appreciable effect of the fuel-initiated mechanism of heating in the analyzed C–H–O–N–Mesystems, has been shown in the paper.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"2014 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82612928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-449-454
Ya. N. Kovalev, A. V. Sаvukhа, V. V. Girinsky
The possibility of using local materials in the construction of structural layers of pavement is considered in the paper. The paper presents a method of technical and economic analysis, for which it is necessary to know the calculated deformation moduli of the materials being compared. Knowing the turnaround time for each of the options under consideration, it is possible, by comparing them with the payback periods, to more fully identify the technical and economic features of such options. The main criterion for the admissibility of the use of local material in the corresponding structural layer is the equal strength of pavement structures or individual structural layers made of local and imported materials. The criterion of economic feasibility of using local material can be written as an inequality. Using the principle of equivalence of systems, it is possible to replace individual structural layers of pavement, made of certain materials, with equivalent layers of stiffness from other materials, increasing or decreasing their thickness, depending on the strength characteristics of the materials themselves. The main condition for the technical feasibility of using local material has been determined on the basis of the condition of equal strength structures made from local and imported materials. A schedule for preliminary determination of the technical and economic feasibility of using local materials in the structural layers of road pavements has been built. The total value of the investment costs can be used as an additional criterion for the economic benefits of the compared options.
{"title":"Feasibility Study Comparison of Pavement Designs Using Local Materials","authors":"Ya. N. Kovalev, A. V. Sаvukhа, V. V. Girinsky","doi":"10.21122/2227-1031-2021-20-5-449-454","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-449-454","url":null,"abstract":"The possibility of using local materials in the construction of structural layers of pavement is considered in the paper. The paper presents a method of technical and economic analysis, for which it is necessary to know the calculated deformation moduli of the materials being compared. Knowing the turnaround time for each of the options under consideration, it is possible, by comparing them with the payback periods, to more fully identify the technical and economic features of such options. The main criterion for the admissibility of the use of local material in the corresponding structural layer is the equal strength of pavement structures or individual structural layers made of local and imported materials. The criterion of economic feasibility of using local material can be written as an inequality. Using the principle of equivalence of systems, it is possible to replace individual structural layers of pavement, made of certain materials, with equivalent layers of stiffness from other materials, increasing or decreasing their thickness, depending on the strength characteristics of the materials themselves. The main condition for the technical feasibility of using local material has been determined on the basis of the condition of equal strength structures made from local and imported materials. A schedule for preliminary determination of the technical and economic feasibility of using local materials in the structural layers of road pavements has been built. The total value of the investment costs can be used as an additional criterion for the economic benefits of the compared options.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"29 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91270501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-420-426
P. I. Yukhnevskiy
Nitrogen-containing compounds that enter concrete together with raw materials, in particular with chemical modifiers of concrete mixture and concrete, as well as those present in Portland cement, are capable of forming ammonia as a result of decomposition. The processes of formation and emission of ammonia cause both a deterioration of the atmosphere of residential premises and are the reason for a decrease in the strength and operational safety indicators of reinforced concrete structures. These circumstances necessitate research and development of methods for determining the safe amount of ammoniumcontaining additives in concrete. Most often, nitrogen-containing compounds contain plasticizing additives, antifreeze and complex additives, as well as setting and hardening accelerators. According to Amendment No 2 STB (Standards of the Republic of Belarus) 1112–98 “Additives for Concrete. General Requirements”, the content of ammonium ions in additives should not exceed 100 mg/kg (except for antifreeze). At the same time, some additives, including plasticizers, which have been successfully used for more than one year without identified problems with ammonia emission, do not fit into the established norm. To determine the maximum permissible concentration (MPC) of ammonium salts in concrete, it is necessary to know the dependence of the emission of ammonia from concrete on various factors, in particular, on the mass content of salts in concrete, the surface area from which ammonia is emitted, the mass of concrete structures, temperature, humidity and air exchange rate in the room. To a lesser extent, the ammonia emission will be affected by the characteristics of the concrete and the reaction conditions for the hydrolysis of salts in the concrete. The paper provides formulas for calculating the emission of ammonia from concrete with the introduction of various ammonium-containing additives. It is shown that, in spite оf the above-standard content of ammonium ions in additives C-3, LST and UP-4, the emission of ammonia from concrete in some cases does not exceed the established maximum permissible concentration (MPC). The volume of ammonia emission from concrete is determined not only by the amount of ammonium ions in the additives, but also to a large extent by the structural and technological scheme of the building and the parameters of the concrete loading of the room. With the known MPC in the air of the room, the given parameters of loading the room with concrete, the formula allows you to calculate the maximum concentration of the additive in the concrete mixture, not exceeding which will ensure compliance with the MPC for ammonia in the air of the premises.
{"title":"On Issue of Permissible Content of Ammonium Ions in Chemical Additives for Concrete","authors":"P. I. Yukhnevskiy","doi":"10.21122/2227-1031-2021-20-5-420-426","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-420-426","url":null,"abstract":"Nitrogen-containing compounds that enter concrete together with raw materials, in particular with chemical modifiers of concrete mixture and concrete, as well as those present in Portland cement, are capable of forming ammonia as a result of decomposition. The processes of formation and emission of ammonia cause both a deterioration of the atmosphere of residential premises and are the reason for a decrease in the strength and operational safety indicators of reinforced concrete structures. These circumstances necessitate research and development of methods for determining the safe amount of ammoniumcontaining additives in concrete. Most often, nitrogen-containing compounds contain plasticizing additives, antifreeze and complex additives, as well as setting and hardening accelerators. According to Amendment No 2 STB (Standards of the Republic of Belarus) 1112–98 “Additives for Concrete. General Requirements”, the content of ammonium ions in additives should not exceed 100 mg/kg (except for antifreeze). At the same time, some additives, including plasticizers, which have been successfully used for more than one year without identified problems with ammonia emission, do not fit into the established norm. To determine the maximum permissible concentration (MPC) of ammonium salts in concrete, it is necessary to know the dependence of the emission of ammonia from concrete on various factors, in particular, on the mass content of salts in concrete, the surface area from which ammonia is emitted, the mass of concrete structures, temperature, humidity and air exchange rate in the room. To a lesser extent, the ammonia emission will be affected by the characteristics of the concrete and the reaction conditions for the hydrolysis of salts in the concrete. The paper provides formulas for calculating the emission of ammonia from concrete with the introduction of various ammonium-containing additives. It is shown that, in spite оf the above-standard content of ammonium ions in additives C-3, LST and UP-4, the emission of ammonia from concrete in some cases does not exceed the established maximum permissible concentration (MPC). The volume of ammonia emission from concrete is determined not only by the amount of ammonium ions in the additives, but also to a large extent by the structural and technological scheme of the building and the parameters of the concrete loading of the room. With the known MPC in the air of the room, the given parameters of loading the room with concrete, the formula allows you to calculate the maximum concentration of the additive in the concrete mixture, not exceeding which will ensure compliance with the MPC for ammonia in the air of the premises.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"45 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90229234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-434-444
Я. Груданов, техн. наук, доценты Г. И. Белохвостов, Людмила Т. Ткачева, V. Grudanov, G. I. Belokhvostov, L. T. Tkacheva
A methodological method based on the use of the theory of preferred numbers has been proposed in order to improve the most important parameters of the working bodies of noise mufflers. As a result of many years of scientific research, the authors have established a previously unknown theoretical relationship between the main series of preferred numbers, golden ratio and Fibonacci series numbers. A new direction in the development of number theory has been considered in the paper, its classification has been compiled, including the geometric theory of numbers, preferred numbers, containing a new basic series of preferred numbers using the Fibonacci sequence. New formulas have been obtained to determine the denominators of geometric progressions for the series of preferred numbers and the area of a circle. Determining the area of a circle using the new formula allows to get more accurate values. A new formula for determining the circumference of a circle has also been derived. The designs of perforated partitions have been developed, in which the laws of the new basic series of preferred numbers are used. Determining the area of a circle using the new formula allows you to get more accurate values. A new formula for determining the circumference of a circle is also obtained. The designs of perforated partitions have been developed, in which the regularities of the new basic series of preferred numbers have been used. A calculated substantiation of the main geometric and structural dimensions of noise mufflers is given using a mathematical model of a perforated golden partition and new basic series of preferred numbers, which allow to obtain a noise muffler design that has the lowest possible aerodynamic resistance with the maximum possible reduction in the noise level of exhaust gases from internal combustion engines. An innovative model of a noise muffler for reciprocating internal combustion engines with improved hydraulic and acoustic characteristics based on the theory of numbers is proposed in the paper. The theory of preferred numbers applies to any technical device.
{"title":"Scientific and Practical Approaches to Improving Noise Muffler Designs of Piston Internal Combustion Engines Based on Theory of Numbers","authors":"Я. Груданов, техн. наук, доценты Г. И. Белохвостов, Людмила Т. Ткачева, V. Grudanov, G. I. Belokhvostov, L. T. Tkacheva","doi":"10.21122/2227-1031-2021-20-5-434-444","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-434-444","url":null,"abstract":"A methodological method based on the use of the theory of preferred numbers has been proposed in order to improve the most important parameters of the working bodies of noise mufflers. As a result of many years of scientific research, the authors have established a previously unknown theoretical relationship between the main series of preferred numbers, golden ratio and Fibonacci series numbers. A new direction in the development of number theory has been considered in the paper, its classification has been compiled, including the geometric theory of numbers, preferred numbers, containing a new basic series of preferred numbers using the Fibonacci sequence. New formulas have been obtained to determine the denominators of geometric progressions for the series of preferred numbers and the area of a circle. Determining the area of a circle using the new formula allows to get more accurate values. A new formula for determining the circumference of a circle has also been derived. The designs of perforated partitions have been developed, in which the laws of the new basic series of preferred numbers are used. Determining the area of a circle using the new formula allows you to get more accurate values. A new formula for determining the circumference of a circle is also obtained. The designs of perforated partitions have been developed, in which the regularities of the new basic series of preferred numbers have been used. A calculated substantiation of the main geometric and structural dimensions of noise mufflers is given using a mathematical model of a perforated golden partition and new basic series of preferred numbers, which allow to obtain a noise muffler design that has the lowest possible aerodynamic resistance with the maximum possible reduction in the noise level of exhaust gases from internal combustion engines. An innovative model of a noise muffler for reciprocating internal combustion engines with improved hydraulic and acoustic characteristics based on the theory of numbers is proposed in the paper. The theory of preferred numbers applies to any technical device.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"69 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72721518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-383-389
A. Ivanov, M. Puzyrev, E. Chikishev
One of the main problems in the design of agricultural machines, including tillage machines, is to ensure the optimal energy intensity of various technological operations. The design, kinematic and technological parameters of rotary tillage machines have a significant impact on the indicators of the energy intensity of the process and the quality of tillage. These parameters include the diameter of the operating body of the agricultural machine, the angular speed and rotational speed of the disks, the number of cutting elements, the translational speed of the operating body, the height of the ridge formed during soil cultivation, the thickness of the cut chips. An important agrotechnical parameter of a rotary tillage machine is the ridging of the furrow bottom. The height of the ridges formed should not be less than 20 % of the depth of the cultivated soil. Currently, in order to ensure the required height of the ridges in the designs of rotary machines, there are a number of restrictions that determine the operating mode and parameters of the units. The degree of influence of the parameters of the developed operating body and the energy consumption on the quality of tillage has been assessed in the process of the research. The experiments have been carried out on an installation that included an operating body, a power unit, control and instrumentation equipment. As the power section, AC motors with a phase rotor were used, the power of which was 0.75 and 1.50 kW, and the speed of rotation was 920, 1500 and 3000 rpm. The parameters have been set that allow to reduce the energy consumption for tillage by 11–17 %, compared to existing machines, and ensure the alignment of the furrow bottom by up to 80 %.
{"title":"Development and Rationale of Two-Disk Operating Body of Agricultural Machine for Tillage","authors":"A. Ivanov, M. Puzyrev, E. Chikishev","doi":"10.21122/2227-1031-2021-20-5-383-389","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-383-389","url":null,"abstract":"One of the main problems in the design of agricultural machines, including tillage machines, is to ensure the optimal energy intensity of various technological operations. The design, kinematic and technological parameters of rotary tillage machines have a significant impact on the indicators of the energy intensity of the process and the quality of tillage. These parameters include the diameter of the operating body of the agricultural machine, the angular speed and rotational speed of the disks, the number of cutting elements, the translational speed of the operating body, the height of the ridge formed during soil cultivation, the thickness of the cut chips. An important agrotechnical parameter of a rotary tillage machine is the ridging of the furrow bottom. The height of the ridges formed should not be less than 20 % of the depth of the cultivated soil. Currently, in order to ensure the required height of the ridges in the designs of rotary machines, there are a number of restrictions that determine the operating mode and parameters of the units. The degree of influence of the parameters of the developed operating body and the energy consumption on the quality of tillage has been assessed in the process of the research. The experiments have been carried out on an installation that included an operating body, a power unit, control and instrumentation equipment. As the power section, AC motors with a phase rotor were used, the power of which was 0.75 and 1.50 kW, and the speed of rotation was 920, 1500 and 3000 rpm. The parameters have been set that allow to reduce the energy consumption for tillage by 11–17 %, compared to existing machines, and ensure the alignment of the furrow bottom by up to 80 %.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"23 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82153316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-07DOI: 10.21122/2227-1031-2021-20-5-405-409
S. V. Bosakov
Contact problems for elastic stripes have been well studied and published in domestic scientific literature. This is partly due to the fact that normative documents on the foundation structure it is recommended to use this elastic foundation model for simulation of a “structure – foundation – soil foundation” system. Two variants of boundary conditions at the contact between a half-strip and a rigid non-deformable base are usually considered. The first boundary condition nullifies the vertical displacements and tangential stresses, the second one nullifies vertical and horizontal displacements. Contact problems for an elastic half-strip are much less investigated. The paper considers this contact problem when the first boundary condition for zeroing of vertical displacements and tangential stresses at the contact of a half-strip with a rigid, nondeformable base. When performing calculations in the traditional formulation without taking into account tangential stresses in the contact zone, the Zhemochkin method has been used, which reduces the solution of the contact problem of solid mechanics to the solution of a statically indeterminate problem by the mixed method of structural mechanics. Therefore, at first, we have found the displacements of the upper edge of the half-strip from the unit load uniformly distributed over the edge section. The resulting expression is used to compose a system of equations for the Zhemochkin method. The case of translational displacement of the die has been considered, and the graph of contact stress distribution under the die's sole has been given in the paper.
{"title":"To Solution of Contact Problem for Elastic Half-Strip","authors":"S. V. Bosakov","doi":"10.21122/2227-1031-2021-20-5-405-409","DOIUrl":"https://doi.org/10.21122/2227-1031-2021-20-5-405-409","url":null,"abstract":"Contact problems for elastic stripes have been well studied and published in domestic scientific literature. This is partly due to the fact that normative documents on the foundation structure it is recommended to use this elastic foundation model for simulation of a “structure – foundation – soil foundation” system. Two variants of boundary conditions at the contact between a half-strip and a rigid non-deformable base are usually considered. The first boundary condition nullifies the vertical displacements and tangential stresses, the second one nullifies vertical and horizontal displacements. Contact problems for an elastic half-strip are much less investigated. The paper considers this contact problem when the first boundary condition for zeroing of vertical displacements and tangential stresses at the contact of a half-strip with a rigid, nondeformable base. When performing calculations in the traditional formulation without taking into account tangential stresses in the contact zone, the Zhemochkin method has been used, which reduces the solution of the contact problem of solid mechanics to the solution of a statically indeterminate problem by the mixed method of structural mechanics. Therefore, at first, we have found the displacements of the upper edge of the half-strip from the unit load uniformly distributed over the edge section. The resulting expression is used to compose a system of equations for the Zhemochkin method. The case of translational displacement of the die has been considered, and the graph of contact stress distribution under the die's sole has been given in the paper.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"81 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76851733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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