Pub Date : 2020-01-01DOI: 10.18323/2073-5073-2020-3-53-64
K. Shakhnazarov
: The existing numerous experimentally-built phase equilibrium diagrams of nonferrous alloys reflect the specific character of interaction of the components at their different ratios and different temperatures and give an idea of the so-called “metallographic” structure of alloys. In general, the literature sources establish a rather good relation between the structu re and the properties, which allows controlling properties, predicting their possible change when varying the components concentrations and the structure forming conditions. However, the applied criteria, which sometimes allow explaining and predicting the level of the achieved properties according to phase equilibrium diagram appearance, do not make it possible to explain the nature of a rather large number of existing anomalies of physicomechanical properties of the industrially used nonferrous alloys. Based on the study of numerous literature data, the author identified the regularity, which allows establishing a relationship between the anomalies in the physicomechanical properties of nonferrous alloys and phase equilibrium diagrams. The author introduced the concept of phase equilibrium diagram as the concentration dependence of the qualitative changes in the crystallization (recrystallization) intervals, which makes it possible to associate the phase equilibrium diagram with the extreme values of physicomechanical properties, which cannot be explained by the peculiarities of the phase composition or structure. The author developed the technique that allows associating anomalies in the properties of alloys with phase equilibrium diagrams based on the first established criterion – a qualitative change (temperature ex-tension) of the cr ystallization (recrystallization) interval (Q∆LS), as well as with a difference in the structural heredity (g e-nealogy) of the component atoms that make up the dual system. The joint analysis of the anomalies in the properties of binary alloys with state di agrams (based on the established criterion (Q∆LS)) allows relating the latter to the presence of intermediate phases in the Cu – Zn, Cu – Sn, Cu – Si, Al –Cu, Al−Si, Al−Mg, Al– Cu – Mg, Cu – Mn systems. Based on the identified regularity of the relationship between the anomalies of physicomechanical properties of alloys and the qualitative changes in the crystallization (recrystallization) interval (Q∆LS), the author proposes an alternative version of Kurnakov’s law.
{"title":"The regularities of the relationship between the anomalies of physicomechanical properties of nonferrous alloys and phase equilibrium diagrams","authors":"K. Shakhnazarov","doi":"10.18323/2073-5073-2020-3-53-64","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-3-53-64","url":null,"abstract":": The existing numerous experimentally-built phase equilibrium diagrams of nonferrous alloys reflect the specific character of interaction of the components at their different ratios and different temperatures and give an idea of the so-called “metallographic” structure of alloys. In general, the literature sources establish a rather good relation between the structu re and the properties, which allows controlling properties, predicting their possible change when varying the components concentrations and the structure forming conditions. However, the applied criteria, which sometimes allow explaining and predicting the level of the achieved properties according to phase equilibrium diagram appearance, do not make it possible to explain the nature of a rather large number of existing anomalies of physicomechanical properties of the industrially used nonferrous alloys. Based on the study of numerous literature data, the author identified the regularity, which allows establishing a relationship between the anomalies in the physicomechanical properties of nonferrous alloys and phase equilibrium diagrams. The author introduced the concept of phase equilibrium diagram as the concentration dependence of the qualitative changes in the crystallization (recrystallization) intervals, which makes it possible to associate the phase equilibrium diagram with the extreme values of physicomechanical properties, which cannot be explained by the peculiarities of the phase composition or structure. The author developed the technique that allows associating anomalies in the properties of alloys with phase equilibrium diagrams based on the first established criterion – a qualitative change (temperature ex-tension) of the cr ystallization (recrystallization) interval (Q∆LS), as well as with a difference in the structural heredity (g e-nealogy) of the component atoms that make up the dual system. The joint analysis of the anomalies in the properties of binary alloys with state di agrams (based on the established criterion (Q∆LS)) allows relating the latter to the presence of intermediate phases in the Cu – Zn, Cu – Sn, Cu – Si, Al –Cu, Al−Si, Al−Mg, Al– Cu – Mg, Cu – Mn systems. Based on the identified regularity of the relationship between the anomalies of physicomechanical properties of alloys and the qualitative changes in the crystallization (recrystallization) interval (Q∆LS), the author proposes an alternative version of Kurnakov’s law.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"os-53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87579196","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-1-49-56
P. Myagkikh, E. Merson, V. Poluyanov, D. Merson, A. Vinogradov
: Low resistance to corrosion and stress corrosion cracking (SCC) hinders the widespread introduction of the magnesium alloys as the construction materials. Considered, that the SCC of the magnesium alloys may be related to the hydrogen fragility. Nevertheless, at the moment, the role of hydrogen in the SCC mechanism of magnesium alloys is not fully evident. In the previous papers, the authors identified that the role of diffusion-active hydrogen in the SCC process of magnesium alloys is highly doubtful: the results both of mechanical tests and gas analysis show that the concentration of diffusion-active hydrogen in tested materials is negligibly small; normally, hydrogen locates in the corrosion products. However, these studies have not identified the influence of external strains on the concentration and state of hydrogen, therefore, it is not clear if the results obtained are typical for SCC only or valid for the corrosion without external load. In this context, the authors set the goal to identify the concentration and the state of hydrogen in magnesium alloys after corrosive action without external strains. Samples of MA14 and MA2-1 alloys and pure magnesium were exposed in a corrosive medium, after which, each sample was divided into two parts: the corrosion products were removed from the first part and left untouched in the second part. Next, the authors studied the samples by gas analysis; and obtained extraction curves and hydrogen concentration values for each of them. The results of the study showed that the removal of corrosion products leads to a strong decline of hydrogen concentration, and at temperatures below 300 °C, it practically ceases. This indicates that most of the hydrogen is in the corrosion products and not in the diffusion-active form in the matrix metal, which is similar to the results obtained when studying the SCC.
{"title":"On the hydrogen state in magnesium alloys after corrosive effect","authors":"P. Myagkikh, E. Merson, V. Poluyanov, D. Merson, A. Vinogradov","doi":"10.18323/2073-5073-2020-1-49-56","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-1-49-56","url":null,"abstract":": Low resistance to corrosion and stress corrosion cracking (SCC) hinders the widespread introduction of the magnesium alloys as the construction materials. Considered, that the SCC of the magnesium alloys may be related to the hydrogen fragility. Nevertheless, at the moment, the role of hydrogen in the SCC mechanism of magnesium alloys is not fully evident. In the previous papers, the authors identified that the role of diffusion-active hydrogen in the SCC process of magnesium alloys is highly doubtful: the results both of mechanical tests and gas analysis show that the concentration of diffusion-active hydrogen in tested materials is negligibly small; normally, hydrogen locates in the corrosion products. However, these studies have not identified the influence of external strains on the concentration and state of hydrogen, therefore, it is not clear if the results obtained are typical for SCC only or valid for the corrosion without external load. In this context, the authors set the goal to identify the concentration and the state of hydrogen in magnesium alloys after corrosive action without external strains. Samples of MA14 and MA2-1 alloys and pure magnesium were exposed in a corrosive medium, after which, each sample was divided into two parts: the corrosion products were removed from the first part and left untouched in the second part. Next, the authors studied the samples by gas analysis; and obtained extraction curves and hydrogen concentration values for each of them. The results of the study showed that the removal of corrosion products leads to a strong decline of hydrogen concentration, and at temperatures below 300 °C, it practically ceases. This indicates that most of the hydrogen is in the corrosion products and not in the diffusion-active form in the matrix metal, which is similar to the results obtained when studying the SCC.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"186 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81597140","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-1-57-67
M. Panchenko, A. Mikhno, I. Tumbusova, G. Maier, V. Moskvina, E. Melnikov, S. Astafurov, E. Astafurova
: Currently, many technical problems require a comprehensive study of the properties of materials operating in hydrogen-containing environments. The authors investigated the effect of age-hardening on the hydrogen embrittlement and fracture micromechanisms of high-nitrogen austenitic Fe-23Cr-17Mn-0.1C-0.6N (wt. %) steel. For this purpose, using heat treatments, the authors formed in specimens of Fe-23Cr-17Mn-0.1C-0.6N steel the structural phase states characte-rized by different distribution and content of dispersed phases. The experiment determined that the accumulation of hydrogen atoms occurs predominantly in the grains in solution-treated specimens without dispersed phases. This causes the effects of solid solution hardening and leads to a change in the micromechanism of steel fracture from a ductile dimple fracture in the absence of hydrogen to a transgranular fracture by the quasi-cleavage mechanism in hydrogen-charged specimens. It was established that the discontinuous decomposition of austenite with the formation of Cr 2 N cells and austenite depleted in nitrogen, predominantly along the grain boundaries causes the formation of a large fraction of interphase (aus-tenite/Cr 2 N particles) boundaries. Cells of discontinuous decomposition promote hydrogen accumulation along the grain boundaries and cause brittle intergranular fracture of hydrogen-charged specimens during plastic deformation. The study showed that in specimens with the discontinuous decomposition of austenite both along the grain boundaries and spreading into the grain body, plenty of intragranular interphase boundaries (Cr 2 N plates in austenite) are formed, which causes the formation of a transgranular brittle fracture in the hydrogen-charged specimens.
{"title":"The effect of hydrogen charging on the mechanical properties and fracture mechanisms of high-nitrogen chromium-manganese steels after age-hardening","authors":"M. Panchenko, A. Mikhno, I. Tumbusova, G. Maier, V. Moskvina, E. Melnikov, S. Astafurov, E. Astafurova","doi":"10.18323/2073-5073-2020-1-57-67","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-1-57-67","url":null,"abstract":": Currently, many technical problems require a comprehensive study of the properties of materials operating in hydrogen-containing environments. The authors investigated the effect of age-hardening on the hydrogen embrittlement and fracture micromechanisms of high-nitrogen austenitic Fe-23Cr-17Mn-0.1C-0.6N (wt. %) steel. For this purpose, using heat treatments, the authors formed in specimens of Fe-23Cr-17Mn-0.1C-0.6N steel the structural phase states characte-rized by different distribution and content of dispersed phases. The experiment determined that the accumulation of hydrogen atoms occurs predominantly in the grains in solution-treated specimens without dispersed phases. This causes the effects of solid solution hardening and leads to a change in the micromechanism of steel fracture from a ductile dimple fracture in the absence of hydrogen to a transgranular fracture by the quasi-cleavage mechanism in hydrogen-charged specimens. It was established that the discontinuous decomposition of austenite with the formation of Cr 2 N cells and austenite depleted in nitrogen, predominantly along the grain boundaries causes the formation of a large fraction of interphase (aus-tenite/Cr 2 N particles) boundaries. Cells of discontinuous decomposition promote hydrogen accumulation along the grain boundaries and cause brittle intergranular fracture of hydrogen-charged specimens during plastic deformation. The study showed that in specimens with the discontinuous decomposition of austenite both along the grain boundaries and spreading into the grain body, plenty of intragranular interphase boundaries (Cr 2 N plates in austenite) are formed, which causes the formation of a transgranular brittle fracture in the hydrogen-charged specimens.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"2013 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86476232","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-2-42-50
A. Mikhno, M. Panchenko, G. Maier, V. Moskvina, E. Melnikov, S. Astafurov, E. Astafurova
: Nitrogen alloying of austenitic steels increases their corrosion resistance and improves mechanical properties. During heat treatment, high-nitrogen austenitic steels tend to the precipitation hardening and the increase of strength characteristics. In the current paper, the authors studied the effect of the duration of age-hardening at the temperatures of 700 °С and 800 °С on the structure, phase composition, plastic flow behavior, and fracture mechanisms of V -alloyed high nitrogen chrome-manganese austenitic Fe-19Cr-22Mn-1.5V-0.3C-0.86N (mass %) steel. The study revealed that after wa-ter-quenching at 1200 °С, the specimens possess the high strength properties, ductility and contain large (300– 500 nm) (V,Cr)(N,C) particles. Aging at temperatures of 700 °С and 800 °С facilitates complex reactions of austenite discontinuous decomposition with the Cr 2 N-plate formation in grains and continuous decomposition with the formation of vanadium nitride-based particles in austenite. During the long-term aging (50 h at 700 °C and 10 h at 800 °C), the intermetallic σ -phase appears in specimens. At age-hardening, the observed phase transformations cause the changes in macro- and mi-cro-mechanism of fracture in the specimens of steel under the study. In the initial state, the specimens show mainly the ductile transgranular fracture. After age-hardening, the fracture mechanism changes into the mixed mechanism with the elements of brittle intergranular and ductile transgranular fractures. When increasing the duration of aging and imple-mentation of complex reactions of decomposition of solid solution, the specimens are fractured by the quasi-cleavage mechanism. The specimens aged at temperatures of 700 °С and 800 °С have quite similar precipitation hardening mech a-nisms, though the increase in aging temperature leads to the rising of the decomposition rate of solid solution. The sequence of transformations described above and the corresponding sequence of changes in the mechanisms of steel fracture are implemented faster when increasing the aging temperature.
{"title":"Effect of the precipitation hardening on regularities of plastic deformation and fracture mode of V-alloyed high nitrogen austenitic steel","authors":"A. Mikhno, M. Panchenko, G. Maier, V. Moskvina, E. Melnikov, S. Astafurov, E. Astafurova","doi":"10.18323/2073-5073-2020-2-42-50","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-2-42-50","url":null,"abstract":": Nitrogen alloying of austenitic steels increases their corrosion resistance and improves mechanical properties. During heat treatment, high-nitrogen austenitic steels tend to the precipitation hardening and the increase of strength characteristics. In the current paper, the authors studied the effect of the duration of age-hardening at the temperatures of 700 °С and 800 °С on the structure, phase composition, plastic flow behavior, and fracture mechanisms of V -alloyed high nitrogen chrome-manganese austenitic Fe-19Cr-22Mn-1.5V-0.3C-0.86N (mass %) steel. The study revealed that after wa-ter-quenching at 1200 °С, the specimens possess the high strength properties, ductility and contain large (300– 500 nm) (V,Cr)(N,C) particles. Aging at temperatures of 700 °С and 800 °С facilitates complex reactions of austenite discontinuous decomposition with the Cr 2 N-plate formation in grains and continuous decomposition with the formation of vanadium nitride-based particles in austenite. During the long-term aging (50 h at 700 °C and 10 h at 800 °C), the intermetallic σ -phase appears in specimens. At age-hardening, the observed phase transformations cause the changes in macro- and mi-cro-mechanism of fracture in the specimens of steel under the study. In the initial state, the specimens show mainly the ductile transgranular fracture. After age-hardening, the fracture mechanism changes into the mixed mechanism with the elements of brittle intergranular and ductile transgranular fractures. When increasing the duration of aging and imple-mentation of complex reactions of decomposition of solid solution, the specimens are fractured by the quasi-cleavage mechanism. The specimens aged at temperatures of 700 °С and 800 °С have quite similar precipitation hardening mech a-nisms, though the increase in aging temperature leads to the rising of the decomposition rate of solid solution. The sequence of transformations described above and the corresponding sequence of changes in the mechanisms of steel fracture are implemented faster when increasing the aging temperature.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"82 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91422420","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-2-32-41
Горелов Николай Дмитриевич, Попов Всеволод Валериевич, Берников Владимир Владиславович
: The paper considers the possibility of conversion applying of a rocket engine as a sandblasting machine for thermo-abrasive treatment. The higher performance characteristics of a treated surface can be achieved through the expo-sure of the high-temperature two-phase flow accelerated in the device nozzle barrel on the object. The ejection feed of granular abrasive substances determines the relative structural simplicity of the device structure. The authors prove the efficiency of such a device using the gas-dynamic process modeling in the CFD software package, the calculations of which are based on combined equations including the key parameters of both the carrier gas and the solid phase particles. The process modeling considers the influence of the geometry and the specifics equal to the real operating prototype. During further analysis, to determine the optimal mode, the authors investigated the influence of various border conditions on the supersonic two-phase flow. The study considers the mutual influence of gas flow and abrasive solid particles starting from the powder delivery section to the nozzle outlet section. The study presents the comparison of temperature and pressure fields depending on the input values, as well as the fluid velocity fields based on these values. The authors carried out the analysis of the dependence of solid particle motion speed on the coordinate at various initial data of temperature and pressure. The study pays special attention to the consideration of the impact of the k -phase particle size on the speed parameters. During the study, the authors identified the main methods of device adjustment to achieve the required mode parameters. As a result of the analysis, the paper concludes on the efficiency and competitive ability of the thermo-abrasive treatment method under the study.
{"title":"Calculation-theoretical study of characteristics of the two-phase flow in a sandblasting machine","authors":"Горелов Николай Дмитриевич, Попов Всеволод Валериевич, Берников Владимир Владиславович","doi":"10.18323/2073-5073-2020-2-32-41","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-2-32-41","url":null,"abstract":": The paper considers the possibility of conversion applying of a rocket engine as a sandblasting machine for thermo-abrasive treatment. The higher performance characteristics of a treated surface can be achieved through the expo-sure of the high-temperature two-phase flow accelerated in the device nozzle barrel on the object. The ejection feed of granular abrasive substances determines the relative structural simplicity of the device structure. The authors prove the efficiency of such a device using the gas-dynamic process modeling in the CFD software package, the calculations of which are based on combined equations including the key parameters of both the carrier gas and the solid phase particles. The process modeling considers the influence of the geometry and the specifics equal to the real operating prototype. During further analysis, to determine the optimal mode, the authors investigated the influence of various border conditions on the supersonic two-phase flow. The study considers the mutual influence of gas flow and abrasive solid particles starting from the powder delivery section to the nozzle outlet section. The study presents the comparison of temperature and pressure fields depending on the input values, as well as the fluid velocity fields based on these values. The authors carried out the analysis of the dependence of solid particle motion speed on the coordinate at various initial data of temperature and pressure. The study pays special attention to the consideration of the impact of the k -phase particle size on the speed parameters. During the study, the authors identified the main methods of device adjustment to achieve the required mode parameters. As a result of the analysis, the paper concludes on the efficiency and competitive ability of the thermo-abrasive treatment method under the study.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83051307","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-3-65-72
A. Shchegolkov, F. Komarov, I. Parfimovich, O. Milchanin, A. Shchegolkov, A. V. Khrobak, A. V. Semenkova
: In the technology of electricity-conducting polymer composites, the up-to-date topic is the application of modifiers with nanoscale geometric parameters. Such materials are both single-wall and multi-wall carbon nanotubes. The use of multi-wall carbon nanotubes as additives to polymers allows achieving good results associated with the electrical conductivity manifestation at the low percentage ratios of the introduced carbon nanotubes. The study considered two different types of polymers: epoxy resin and silicone. For modification, the authors used the multilayer carbon nanotubes (MCNT). For silicone, the authors studied the electrical conductivity at the mechanical deformations, in particular, at torsion with different twist angles. The study considered the influence of MCNT with different bulk density on the electrical conductivity of composites. At the 100 Hz measurement frequencies for identical additive concentrations with 1, 2, 4, and 8 wt.% in composites with the “Taunit - M” MCNT, the conductivity is about by 2 orders of magnitude larger than in co m-posites with “Taunit” MCNT. A polymer modified by an MCNT with a specific surface a rea of 202.3 m2/g has a lower specific resistivity (3.8 × 105 Ohm×cm). The MCNT modifier with a specific surface area of 202.3 m2/g, which is smaller in comparison with other types of MCNT, and a bulk density of 42.6 kg/m3 allows obtaining the lowest electrical resistivity. An MCNT with a high specific surface area of 541.5 m2/g causes the formation of electrical conductivity by 2 orders of magnitude lower than an MCNT with a specific surface area of 202.3 m2/g. The study identified that at the mass content of MCNT 1.5 and 2 mass.%, the composites are characterized by an increase in electrical resistivity at torsion angles from 0 to 900°.
{"title":"The influence of carbon nanotubes on the electric conductivity of thermosetting plastics and elastomers","authors":"A. Shchegolkov, F. Komarov, I. Parfimovich, O. Milchanin, A. Shchegolkov, A. V. Khrobak, A. V. Semenkova","doi":"10.18323/2073-5073-2020-3-65-72","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-3-65-72","url":null,"abstract":": In the technology of electricity-conducting polymer composites, the up-to-date topic is the application of modifiers with nanoscale geometric parameters. Such materials are both single-wall and multi-wall carbon nanotubes. The use of multi-wall carbon nanotubes as additives to polymers allows achieving good results associated with the electrical conductivity manifestation at the low percentage ratios of the introduced carbon nanotubes. The study considered two different types of polymers: epoxy resin and silicone. For modification, the authors used the multilayer carbon nanotubes (MCNT). For silicone, the authors studied the electrical conductivity at the mechanical deformations, in particular, at torsion with different twist angles. The study considered the influence of MCNT with different bulk density on the electrical conductivity of composites. At the 100 Hz measurement frequencies for identical additive concentrations with 1, 2, 4, and 8 wt.% in composites with the “Taunit - M” MCNT, the conductivity is about by 2 orders of magnitude larger than in co m-posites with “Taunit” MCNT. A polymer modified by an MCNT with a specific surface a rea of 202.3 m2/g has a lower specific resistivity (3.8 × 105 Ohm×cm). The MCNT modifier with a specific surface area of 202.3 m2/g, which is smaller in comparison with other types of MCNT, and a bulk density of 42.6 kg/m3 allows obtaining the lowest electrical resistivity. An MCNT with a high specific surface area of 541.5 m2/g causes the formation of electrical conductivity by 2 orders of magnitude lower than an MCNT with a specific surface area of 202.3 m2/g. The study identified that at the mass content of MCNT 1.5 and 2 mass.%, the composites are characterized by an increase in electrical resistivity at torsion angles from 0 to 900°.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"69 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76900424","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-2-61-67
E. N. Pocheckuev, P. A. Puteev
: The complex sheet parts forming uses double-action presses with an external slider for clamping the workpiece. The quality of sheet metal parts depends on many factors, including the equipment parameters. The part forming shows the external slider displacements during clamping. The kinematics of the multi-link double-action press mechanism affects these displacements. The external slider movement during clamping leads to the clamping force chang-ing and, as a result, to folding. To determine the kinematic displacement of the external slider during clamping, the authors analyzed the kinematics of the press multilink mechanism. The solution proposes a mathematical model of the double-action press kinematics. The authors built a wire-frame CAD-model of the press working parts and, using NX Siemens PLM Software, analyzed its kinematics. It allowed building a cyclogram of the external slider movement and finding the crankshaft rotation angle interval for clamping. This interval contains several local extrema. To find the exact value of the slider displacement in the lower position, the authors built the system of nonlinear displacement equations. Such a system did not have an analytical solution; therefore, its solution was found with numerical analysis. For the local extrema points, the authors found the nonlinear system solutions and obtained the displacement extremal values using the MATLAB software. The study showed that to prevent folding, it is necessary to set the gap between the clamp and matrix, taking into account the kinematic displacement of the external slider during clamping, which can amount up to 1/3 of the thickness of a workpiece of the exterior parts of a vehicle.
{"title":"The analysis of double-action press slider movement","authors":"E. N. Pocheckuev, P. A. Puteev","doi":"10.18323/2073-5073-2020-2-61-67","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-2-61-67","url":null,"abstract":": The complex sheet parts forming uses double-action presses with an external slider for clamping the workpiece. The quality of sheet metal parts depends on many factors, including the equipment parameters. The part forming shows the external slider displacements during clamping. The kinematics of the multi-link double-action press mechanism affects these displacements. The external slider movement during clamping leads to the clamping force chang-ing and, as a result, to folding. To determine the kinematic displacement of the external slider during clamping, the authors analyzed the kinematics of the press multilink mechanism. The solution proposes a mathematical model of the double-action press kinematics. The authors built a wire-frame CAD-model of the press working parts and, using NX Siemens PLM Software, analyzed its kinematics. It allowed building a cyclogram of the external slider movement and finding the crankshaft rotation angle interval for clamping. This interval contains several local extrema. To find the exact value of the slider displacement in the lower position, the authors built the system of nonlinear displacement equations. Such a system did not have an analytical solution; therefore, its solution was found with numerical analysis. For the local extrema points, the authors found the nonlinear system solutions and obtained the displacement extremal values using the MATLAB software. The study showed that to prevent folding, it is necessary to set the gap between the clamp and matrix, taking into account the kinematic displacement of the external slider during clamping, which can amount up to 1/3 of the thickness of a workpiece of the exterior parts of a vehicle.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"153 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78205179","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-4-51-57
A. Shaikin, I. Galiev, D. A. Pavlov, M. V. Sazonov
The paper considers the turbulence intensity and the fuel chemical composition impact on the flame propagation velocity at the initial and main combustion phases when changing the air-fuel mixture composition. The relevance of the study is caused by the fact that currently, the improvement of conventional engine operation characteristics is mainly achieved through the improvement of the fuel mixture combustion process. However, there are no data on the influence of chemical and gas-dynamic factors on the peculiarities of flame propagation at the initial and main combustion phases. The gas reciprocating internal combustion engine was the object of the research, and the subject of the study was the fuel combustion process. Fuel chemical composition changed due to the promoting addition of hydrogen to the natural gas and variations of the excess-air coefficient. The experiments carried out on the UIT-85 power plant (i.e. under the simulated internal combustion engine conditions) show that the promoting addition of hydrogen stronger influences the flame velocity in the initial combustion phase compared to the second combustion phase, as a combustion source in the first phase is a laminar flame bent front and depends only on chemical and thermo-physical properties of the fuel-air mixture. The analysis of experimental data showed the dual impact of turbulence intensity on the flame propagation velocity. In particular, at the beginning of the combustion process, the fluctuating velocity scarcely influences the flame propagation velocity, as opposed to the main combustion phase, where the flame propagation velocity increases at the increase of turbulence intensity.
{"title":"The technologies of improving the process of air-fuel mixture combustion in spark ignition engines","authors":"A. Shaikin, I. Galiev, D. A. Pavlov, M. V. Sazonov","doi":"10.18323/2073-5073-2020-4-51-57","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-4-51-57","url":null,"abstract":"The paper considers the turbulence intensity and the fuel chemical composition impact on the flame propagation velocity at the initial and main combustion phases when changing the air-fuel mixture composition. The relevance of the study is caused by the fact that currently, the improvement of conventional engine operation characteristics is mainly achieved through the improvement of the fuel mixture combustion process. However, there are no data on the influence of chemical and gas-dynamic factors on the peculiarities of flame propagation at the initial and main combustion phases. The gas reciprocating internal combustion engine was the object of the research, and the subject of the study was the fuel combustion process. Fuel chemical composition changed due to the promoting addition of hydrogen to the natural gas and variations of the excess-air coefficient. The experiments carried out on the UIT-85 power plant (i.e. under the simulated internal combustion engine conditions) show that the promoting addition of hydrogen stronger influences the flame velocity in the initial combustion phase compared to the second combustion phase, as a combustion source in the first phase is a laminar flame bent front and depends only on chemical and thermo-physical properties of the fuel-air mixture. The analysis of experimental data showed the dual impact of turbulence intensity on the flame propagation velocity. In particular, at the beginning of the combustion process, the fluctuating velocity scarcely influences the flame propagation velocity, as opposed to the main combustion phase, where the flame propagation velocity increases at the increase of turbulence intensity.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78483193","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 : 2020-01-01DOI: 10.18323/2073-5073-2020-1-7-14
A. B. Vakaeva, G. Shuvalov, S. Kostyrko, O. Sedova
: Most of the advanced construction and functional materials are elastically nonuniform, moreover, for many of them, the elongated holes and inclusions are typical, which are similar to a cylinder in form. The strength and physico-chemical properties of a material, to a great extent, depend on the peculiarities of the strain-stress state of the near-surface and boundary layers of the materials in the heterogeneous systems. The development of the processes of elastic defor-mation and fracture in these areas, to a large extent, determines the mechanical behavior of a material in general and arouses much interest. The authors study the influence of interfacial stresses on the strain-stress state of elastic bimaterial with smooth waveform interface; consider the 2-D solid mechanics problem of an elastic body with nanoscale boundary surface texture, which appears between the nearly circular inclusion and the matrix. It is expected that a body is situated within a uniform stress field. To solve the problem, the authors used the simplified Gurtin–Murdoch’s surface/interface elasticity model, where the interfacial boundary is the negligibly thin layer exactly bordered on the bulk phases. It is acknowledged that there are no displacement discontinuities on the interfacial boundary, and the stress jump is determined by the effect of surface/interfacial stress according to the generalized Laplace–Young law. Using the boundary perturbation method, the problem solution for each-order approximation is limited to a singular integrodifferential equation against the unknown surface/interfacial stress. The paper gives the numerical results for the problem to a first-order approximation. As a result, the authors carry out the comparative analysis of the strain-stress state using the finite-element method and analytical boundary perturbation method.
{"title":"Two approaches to study the effect of surface stresses in an elastic body with a nearly circular nanodefect","authors":"A. B. Vakaeva, G. Shuvalov, S. Kostyrko, O. Sedova","doi":"10.18323/2073-5073-2020-1-7-14","DOIUrl":"https://doi.org/10.18323/2073-5073-2020-1-7-14","url":null,"abstract":": Most of the advanced construction and functional materials are elastically nonuniform, moreover, for many of them, the elongated holes and inclusions are typical, which are similar to a cylinder in form. The strength and physico-chemical properties of a material, to a great extent, depend on the peculiarities of the strain-stress state of the near-surface and boundary layers of the materials in the heterogeneous systems. The development of the processes of elastic defor-mation and fracture in these areas, to a large extent, determines the mechanical behavior of a material in general and arouses much interest. The authors study the influence of interfacial stresses on the strain-stress state of elastic bimaterial with smooth waveform interface; consider the 2-D solid mechanics problem of an elastic body with nanoscale boundary surface texture, which appears between the nearly circular inclusion and the matrix. It is expected that a body is situated within a uniform stress field. To solve the problem, the authors used the simplified Gurtin–Murdoch’s surface/interface elasticity model, where the interfacial boundary is the negligibly thin layer exactly bordered on the bulk phases. It is acknowledged that there are no displacement discontinuities on the interfacial boundary, and the stress jump is determined by the effect of surface/interfacial stress according to the generalized Laplace–Young law. Using the boundary perturbation method, the problem solution for each-order approximation is limited to a singular integrodifferential equation against the unknown surface/interfacial stress. The paper gives the numerical results for the problem to a first-order approximation. As a result, the authors carry out the comparative analysis of the strain-stress state using the finite-element method and analytical boundary perturbation method.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79766919","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 : 2019-12-30DOI: 10.18323/2073-5073-2019-4-19-28
L. Vorochaeva, S. Savin
The paper considers a three-link crawling snake-like robot, the links of which are connected by two-axis hinges. The robot is equipped with four bearing supports with the controlled coefficient of friction between them and the surface. The device is designed to move inside buildings after the emergencies to search for people under the debris and to transport the essentials to them. The robot is controlled by the operator in two modes: the sequential execution of commands (forward, backward, turn, etc.) and moving from the starting point to the final one. Working in each of the control modes requires the use of the gaits bank. The authors developed the classification of gaits for a crawling robot based on several criteria: the admissible periodic separation of links from a surface, the ability to control by friction in the supports, the combinations of controllable bearing supports, and the implemented type of motion. The authors studied in detail the controllable planar gaits of a robot when moving it forward and distinguished four types of gaits: longitudinal, transverse, transverse s-shaped, and longitudinal-transverse. For each gait the sequence of stages is developed, the conditions of their beginning and end imposed on the movements of the links are formulated and the vector of generalized coordinates is defined. As a result of numerical simulation, the authors built the graphs of trajectories of the centers of mass of links and the center of mass of the entire device for each gait, as well as the graphs of time dependences of the angles of rotation of links. The study identified the influence of angles of links relative positions on the distance traveled by the robot. It is revealed that for the same time of movement, the robot will pass the greatest distance with a longitudinal gait irrespective of angles of links relative position. The device will be able to march the same distance at two types of transverse gaits at the maximum possible angle of the links relative position.
{"title":"THE FORMATION OF THE BANK OF GAITS FOR A CRAWLING SEARCH ROBOT WITH CONTROLLABLE FRICTION IN BEARING SUPPORTS","authors":"L. Vorochaeva, S. Savin","doi":"10.18323/2073-5073-2019-4-19-28","DOIUrl":"https://doi.org/10.18323/2073-5073-2019-4-19-28","url":null,"abstract":"The paper considers a three-link crawling snake-like robot, the links of which are connected by two-axis hinges. The robot is equipped with four bearing supports with the controlled coefficient of friction between them and the surface. The device is designed to move inside buildings after the emergencies to search for people under the debris and to transport the essentials to them. The robot is controlled by the operator in two modes: the sequential execution of commands (forward, backward, turn, etc.) and moving from the starting point to the final one. Working in each of the control modes requires the use of the gaits bank. \u0000The authors developed the classification of gaits for a crawling robot based on several criteria: the admissible periodic separation of links from a surface, the ability to control by friction in the supports, the combinations of controllable bearing supports, and the implemented type of motion. The authors studied in detail the controllable planar gaits of a robot when moving it forward and distinguished four types of gaits: longitudinal, transverse, transverse s-shaped, and longitudinal-transverse. For each gait the sequence of stages is developed, the conditions of their beginning and end imposed on the movements of the links are formulated and the vector of generalized coordinates is defined. \u0000As a result of numerical simulation, the authors built the graphs of trajectories of the centers of mass of links and the center of mass of the entire device for each gait, as well as the graphs of time dependences of the angles of rotation of links. The study identified the influence of angles of links relative positions on the distance traveled by the robot. It is revealed that for the same time of movement, the robot will pass the greatest distance with a longitudinal gait irrespective of angles of links relative position. The device will be able to march the same distance at two types of transverse gaits at the maximum possible angle of the links relative position.","PeriodicalId":23555,"journal":{"name":"Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80597737","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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