Pub Date : 2023-06-06DOI: 10.21122/2227-1031-2023-22-3-208-215
É. I. Mikhnevich, Zeming Li
The main canals of reclamation systems, along with the best economic performance, must also meet the requirements for connecting the conductive network in the vertical plane and the technology for the construction of the channel. Although the channels of the hydraulically most advantageous profile are the most economical un terms of excavation volume, often turn out to be too deep and of small width along the bottom, which does not meet the specified requirements. All these factors can be taken into account by slightly reducing the water flow velocity u (compared to the velocity in the channel with the most hydraulically advantageous cross section uh.a.), which leads to a significant decrease in the channel depth and, accordingly, an increase in the width of the channel along the bottom. Such a decrease in velocity is economically justified (without a significant increase in the cross-sectional area) in the region of the most hydraulically advantageous sections, where the curve of the function h = f(u) sharply increases and asymptotically approaches the ordinate with the maximum possible velocity uh.a. This area can be approximately characterized by the values of the velocity u = (0.95–1.0)uh.a. For the convenience of calculation, the formula obtained earlier by the author for the channel depth of the hydraulically most advantageous profile has been converted to a simpler form. An analytical method is proposed for calculating the optimal parameters of the channel section, located in the area of the most hydraulically advantageous sections, which is characterized by the optimization coefficient Kopt = u/uh.a, varying within Kopt. = 0.95–1.0. In this area, the cross section of the channel differs slightly from the most hydraulically advantageous profile, and, at the same time, satisfies the requirements for conjugation of the conductive network in the vertical plane and the conditions of work. The proposed calculation method is less laborious and is applicable in a wide range of changes pertaining to exponent y in the formula of N. N. Pavlovsky to determine the Chezy’s coefficient. The calculation according to the proposed method is performed based on the use of dependencies to determine the characteristics of the most hydraulically advantageous section and the formulas of channel hydraulics (with a slight gradual decrease in the water flow rate u). Formulas are obtained for determining the depth and width of the channel along the bottom at various values of velocity.
{"title":"Optimization of Main Canal Parameters in the Area of Hydraulically Most Advantageous Sections","authors":"É. I. Mikhnevich, Zeming Li","doi":"10.21122/2227-1031-2023-22-3-208-215","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-3-208-215","url":null,"abstract":"The main canals of reclamation systems, along with the best economic performance, must also meet the requirements for connecting the conductive network in the vertical plane and the technology for the construction of the channel. Although the channels of the hydraulically most advantageous profile are the most economical un terms of excavation volume, often turn out to be too deep and of small width along the bottom, which does not meet the specified requirements. All these factors can be taken into account by slightly reducing the water flow velocity u (compared to the velocity in the channel with the most hydraulically advantageous cross section uh.a.), which leads to a significant decrease in the channel depth and, accordingly, an increase in the width of the channel along the bottom. Such a decrease in velocity is economically justified (without a significant increase in the cross-sectional area) in the region of the most hydraulically advantageous sections, where the curve of the function h = f(u) sharply increases and asymptotically approaches the ordinate with the maximum possible velocity uh.a. This area can be approximately characterized by the values of the velocity u = (0.95–1.0)uh.a. For the convenience of calculation, the formula obtained earlier by the author for the channel depth of the hydraulically most advantageous profile has been converted to a simpler form. An analytical method is proposed for calculating the optimal parameters of the channel section, located in the area of the most hydraulically advantageous sections, which is characterized by the optimization coefficient Kopt = u/uh.a, varying within Kopt. = 0.95–1.0. In this area, the cross section of the channel differs slightly from the most hydraulically advantageous profile, and, at the same time, satisfies the requirements for conjugation of the conductive network in the vertical plane and the conditions of work. The proposed calculation method is less laborious and is applicable in a wide range of changes pertaining to exponent y in the formula of N. N. Pavlovsky to determine the Chezy’s coefficient. The calculation according to the proposed method is performed based on the use of dependencies to determine the characteristics of the most hydraulically advantageous section and the formulas of channel hydraulics (with a slight gradual decrease in the water flow rate u). Formulas are obtained for determining the depth and width of the channel along the bottom at various values of velocity.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129940957","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 : 2023-06-06DOI: 10.21122/2227-1031-2023-22-3-186-192
G. A. Bayevich, Y. Nikitjuk, V. Myshkovets, A. V. Maximenko, I. Aushev
Using the MOGA genetic algorithm built into the DesignXplorer module of the ANSYS Workbench program, optimization of laser processing of 12Х18Н9Т-steel by annular beams has been performed. The calculation of temperature fields has been carried out taking into account the dependence of the thermophysical properties of the material on temperature by the finite element method in the ANSYS Workbench program. A regression model has been obtained for processing 12Х18Н9Т-steel by annular laser beams using a face-centered variant of the central compositional plan of the experiment. The power density and duration of laser radiation pulses, the outer and inner diameters of the laser beam in the processing plane were used as variable factors. The penetration depths of the material and the maximum temperatures in the laser processing zone were used as responses. The influence of processing parameters on the penetration depths of the material in the laser impact zone and the maximum temperature values has been evaluated. It has been established that the depth of penetration of the material and the maximum temperatures are most affected by the power density of laser radiation. Optimization of laser processing of 12Х18Н9Т-steel by annular beams was carried out by setting the limiting values of the maximum tempe-rature in the processing zone for three variants of the minimum penetration depth. The parameters obtained as a result of optimization using the MOGA algorithm and the parameters obtained as a result of finite element modeling are compared. The maximum relative error of the results when determining the maximum temperatures did not exceed 1 % and when determining the maximum penetration depths did not exceed 6 %.
{"title":"Optimization of 12Х18Н9Т-Steel Processing by Ring Laser Beams","authors":"G. A. Bayevich, Y. Nikitjuk, V. Myshkovets, A. V. Maximenko, I. Aushev","doi":"10.21122/2227-1031-2023-22-3-186-192","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-3-186-192","url":null,"abstract":"Using the MOGA genetic algorithm built into the DesignXplorer module of the ANSYS Workbench program, optimization of laser processing of 12Х18Н9Т-steel by annular beams has been performed. The calculation of temperature fields has been carried out taking into account the dependence of the thermophysical properties of the material on temperature by the finite element method in the ANSYS Workbench program. A regression model has been obtained for processing 12Х18Н9Т-steel by annular laser beams using a face-centered variant of the central compositional plan of the experiment. The power density and duration of laser radiation pulses, the outer and inner diameters of the laser beam in the processing plane were used as variable factors. The penetration depths of the material and the maximum temperatures in the laser processing zone were used as responses. The influence of processing parameters on the penetration depths of the material in the laser impact zone and the maximum temperature values has been evaluated. It has been established that the depth of penetration of the material and the maximum temperatures are most affected by the power density of laser radiation. Optimization of laser processing of 12Х18Н9Т-steel by annular beams was carried out by setting the limiting values of the maximum tempe-rature in the processing zone for three variants of the minimum penetration depth. The parameters obtained as a result of optimization using the MOGA algorithm and the parameters obtained as a result of finite element modeling are compared. The maximum relative error of the results when determining the maximum temperatures did not exceed 1 % and when determining the maximum penetration depths did not exceed 6 %.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"917 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131735462","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 : 2023-06-06DOI: 10.21122/2227-1031-2023-22-3-216-223
D. Snezhkov, S. Leonovich, N. Budrevich
The homogeneity of the structure of the boired pile shaft has been studied based on the results of four-channel inter-well ultrasonic (US) monitoring. The actual lengthy of the piles has been determined with the detection of defragmentation of the pile shaft, the compressive defects have been determined, and continuity defects have been identified based on a joint analysis of data from the method of interwell ultrasonic monitoring. The use of four channels allows to control separately the peripheral and central areas of the pile in six directions. The data of the seismoacoustic method coincided with the parameters of ultrasonic monitoring in terms of identifying zones of concrete heterogeneity, reducing the pile cross section, etc. For all of the listed piles, data are not registered by the named test methods indicating defragmentation of the pile shaft – the presence of sections in the cross sections of which there is no concrete at all. These test methods for all piles confirmed the compliance of their actual length with the design values. A significant defect in the continuity of the concrete of the 40op pile, according to the data of ultrasonic monitoring and seismoacoustic method, was registered in the interval of marks – (17.5–18) m, manifesting itself a sa decrease in the propagation velocity of the ultrasonic pulse from 25 to 50 % in two sounding directions, inclu-ding diametrical. This defect can be interpreted as a decrease in the effective section of the pile to 25–50 % of the average value. Defective sections of piles were found in their upper part at depth marks from 0 to –1.5 m, counting from the end surface of the head. At the same time, differences in the physical and mechanical parameters of concrete at these marks were also observed within the cross section of piles [1–5].
{"title":"Homogeneity of Bored Piles According to Results of Four-Channel Cross-Well Ultrasonic Monitoring","authors":"D. Snezhkov, S. Leonovich, N. Budrevich","doi":"10.21122/2227-1031-2023-22-3-216-223","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-3-216-223","url":null,"abstract":"The homogeneity of the structure of the boired pile shaft has been studied based on the results of four-channel inter-well ultrasonic (US) monitoring. The actual lengthy of the piles has been determined with the detection of defragmentation of the pile shaft, the compressive defects have been determined, and continuity defects have been identified based on a joint analysis of data from the method of interwell ultrasonic monitoring. The use of four channels allows to control separately the peripheral and central areas of the pile in six directions. The data of the seismoacoustic method coincided with the parameters of ultrasonic monitoring in terms of identifying zones of concrete heterogeneity, reducing the pile cross section, etc. For all of the listed piles, data are not registered by the named test methods indicating defragmentation of the pile shaft – the presence of sections in the cross sections of which there is no concrete at all. These test methods for all piles confirmed the compliance of their actual length with the design values. A significant defect in the continuity of the concrete of the 40op pile, according to the data of ultrasonic monitoring and seismoacoustic method, was registered in the interval of marks – (17.5–18) m, manifesting itself a sa decrease in the propagation velocity of the ultrasonic pulse from 25 to 50 % in two sounding directions, inclu-ding diametrical. This defect can be interpreted as a decrease in the effective section of the pile to 25–50 % of the average value. Defective sections of piles were found in their upper part at depth marks from 0 to –1.5 m, counting from the end surface of the head. At the same time, differences in the physical and mechanical parameters of concrete at these marks were also observed within the cross section of piles [1–5].","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126065518","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 : 2023-06-06DOI: 10.21122/2227-1031-2023-22-3-193-198
A. S. Kozeruk, A. A. Sukhotsky, M. Filonova, V. I. Yurinok, V. О. Kuznechik
Mathematical modeling of the processing of balls by the method of free lapping using a tool in the form of a hollow thin-walled cylinder (tool bushings) has been performed. An analytical expression has been obtained for calculating the cutting paths, which, according to the formula of F. Preston, are proportional to the amount of material removal from the workpiece being processed. The calculation of the cutting paths in the diametrical sections of the ball during its rotation by a total angle of 4000 radians was carried out. The calculation is performed for various values of such adjustment parameters of the base machine as the amplitude of the reciprocating rotational movement of the device with tool bushings fixed in it, the distance between the symmetry axes of the tool bushings and the axis of rotation of the device, the speed of rotation of the input link of the actuator mechanism of the base machine and a faceplate fixed on its spindle and serving to communicate relative rotation to the ball blanks. In this case, the section with the greatest divergence of cutting paths was considered and the relative value of these paths was determined, which is proportional to the accuracy of processing. Studies have been carried out that have made it possible to identify at least three locations of tool bushings, in which the minimum value of the relative cutting paths on the machined ball surface is achieved, i. e. maximum accuracy of processing, which makes it possible in practice to combine the operations of preliminary, main and final grinding of the parts under consideration. It is shown that the degree of correlation between experimental and theoretical results is at the level of 80–85 %, and the polishing performance according to the proposed scheme increases by about 30 % in comparison with the classical scheme for performing this operation.
{"title":"Modeling of the Process of Shaping Glass Beads According to the Method of Free Lapping","authors":"A. S. Kozeruk, A. A. Sukhotsky, M. Filonova, V. I. Yurinok, V. О. Kuznechik","doi":"10.21122/2227-1031-2023-22-3-193-198","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-3-193-198","url":null,"abstract":"Mathematical modeling of the processing of balls by the method of free lapping using a tool in the form of a hollow thin-walled cylinder (tool bushings) has been performed. An analytical expression has been obtained for calculating the cutting paths, which, according to the formula of F. Preston, are proportional to the amount of material removal from the workpiece being processed. The calculation of the cutting paths in the diametrical sections of the ball during its rotation by a total angle of 4000 radians was carried out. The calculation is performed for various values of such adjustment parameters of the base machine as the amplitude of the reciprocating rotational movement of the device with tool bushings fixed in it, the distance between the symmetry axes of the tool bushings and the axis of rotation of the device, the speed of rotation of the input link of the actuator mechanism of the base machine and a faceplate fixed on its spindle and serving to communicate relative rotation to the ball blanks. In this case, the section with the greatest divergence of cutting paths was considered and the relative value of these paths was determined, which is proportional to the accuracy of processing. Studies have been carried out that have made it possible to identify at least three locations of tool bushings, in which the minimum value of the relative cutting paths on the machined ball surface is achieved, i. e. maximum accuracy of processing, which makes it possible in practice to combine the operations of preliminary, main and final grinding of the parts under consideration. It is shown that the degree of correlation between experimental and theoretical results is at the level of 80–85 %, and the polishing performance according to the proposed scheme increases by about 30 % in comparison with the classical scheme for performing this operation.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129097461","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 : 2023-06-06DOI: 10.21122/2227-1031-2023-22-3-199-207
P. A. Avgustovsky, V. M. Komarovskaya
Cardiovascular diseases, and in particular, coronary heart disease are the most common cause of death worldwide. Finding the most effective method of treatment seems to be an advanced task. Stenting is a minimally invasive effective way to solve this problem. Immediately with the advent of endoprostheses (stents), there was a problem of repeated vasoconstriction (restenosis) due to neointimal hyperplasia (excessive build-up of the inner shell of the vessel), the causes of which are the release of metal ions from the stent material, damage to the artery wall during implantation, allergic reactions. Initially, they tried to find a solution by searching for the optimal design and material of the stent, as evidenced by the release of more than five hundred models of intravascular endoprostheses differing in design, material, geometric shape, profile, overall dimensions and other parameters. Currently, the most effective way to solve the problems of biocompatibility of stent materials is the formation of coatings on the surface of stents. It is possible to distinguish a number of different intravascular endoprostheses with modifiable coatings: secreting medicinal substances, with biodegradable coatings, with bioactive coatings. The paper presents the results of the analysis of the literature sources of the most advanced research in the field of surface modification of intravascular endoprostheses, which allowed to justify the choice of titanium oxynitride coating as recommended for further optimization and application due to high corrosion resistance, biocompatibility with cells, tissues and fluids of the human body, a good level of adhesion. At the same time there are a number of limiting factors associated with obtaining such coatings while maintaining all structural and technological requirements.
{"title":"Current Trends in Improving Functional Properties of Intravascular Endoprostheses","authors":"P. A. Avgustovsky, V. M. Komarovskaya","doi":"10.21122/2227-1031-2023-22-3-199-207","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-3-199-207","url":null,"abstract":"Cardiovascular diseases, and in particular, coronary heart disease are the most common cause of death worldwide. Finding the most effective method of treatment seems to be an advanced task. Stenting is a minimally invasive effective way to solve this problem. Immediately with the advent of endoprostheses (stents), there was a problem of repeated vasoconstriction (restenosis) due to neointimal hyperplasia (excessive build-up of the inner shell of the vessel), the causes of which are the release of metal ions from the stent material, damage to the artery wall during implantation, allergic reactions. Initially, they tried to find a solution by searching for the optimal design and material of the stent, as evidenced by the release of more than five hundred models of intravascular endoprostheses differing in design, material, geometric shape, profile, overall dimensions and other parameters. Currently, the most effective way to solve the problems of biocompatibility of stent materials is the formation of coatings on the surface of stents. It is possible to distinguish a number of different intravascular endoprostheses with modifiable coatings: secreting medicinal substances, with biodegradable coatings, with bioactive coatings. The paper presents the results of the analysis of the literature sources of the most advanced research in the field of surface modification of intravascular endoprostheses, which allowed to justify the choice of titanium oxynitride coating as recommended for further optimization and application due to high corrosion resistance, biocompatibility with cells, tissues and fluids of the human body, a good level of adhesion. At the same time there are a number of limiting factors associated with obtaining such coatings while maintaining all structural and technological requirements. ","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122473453","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 : 2023-06-05DOI: 10.21122/2227-1031-2023-22-3-179-185
F. Panteleenko, V. Okovity, O. S. Devoino, A. A. Litvinko, V. V. Okovity, V. Astashinsky, V. M. Blumenstein
In the work, taking into account the state of the issue in the field of applying multilayer heat-shielding and wear-resistant coatings, directions of research are substantiated. The objectives of the development are: improvement of powder materials containing zirconium dioxide partially stabilized with yttrium oxide for plasma deposition of heat-shielding coa-tings; improvement of powder materials containing oxide ceramics and nickel-based alloys for plasma deposition of wear-resistant coatings; development of technological parameters of plasma spraying and subsequent processing by the effects of compression plasma on the coating; analysis of the quality of protective coatings obtained using the optimal technology by studying their structure and physical and mechanical properties. The ZrO2 – 7 % Y2O3 particles contain the predominant tetragonal Y0.15Zr0.85O0.93 phase, monoclinic and cubic ZrO2 phases, and the Al2O3–TiO2–Ni–Cr–Al–Y–Ta composition contains the Cr1.12Ni2.88 phase of the nickel-based solid solution, the a-Al2O3, g-Al2O3 phases, and the orthorhombic phase of titanium oxide TiO2 that contribute to its wear resistance. subsequent optimization of technological parameters for the process of plasma spraying of multilayer heat-shielding and wear-resistant coatings. Technological parameters for the process of plasma spraying of multi-layer heat-shielding and wear-resistant coatings are investigated with subsequent optimization. The optimization criteria were the utilization factor of the sprayed powder material and the structure of the coatings. The influence of the spraying distance on the values of operational characteristics of the formed plasma coatings on Al2O3–TiO2–Ni–Cr–Al–Y–Ta has been studied. The obtained results of controlling the phase composition of coatings by varying the chemical composition of powder materials are presented. In the process of deposition, the differences in the phase composition of the formed material are the more significant, the more inhomogeneous the distribution of elements in the initial powder material. Tests have been carried out for cyclic testing in an oven at a maximum temperature within 1300 °C of heat-shielding coatings to determine their heat resistance. They proved the influence of the phase composition of the formed coatings on their ability to withstand high-temperature oxidation.
{"title":"Aspects of Creating Multilayer Coatings by Plasma Spraying","authors":"F. Panteleenko, V. Okovity, O. S. Devoino, A. A. Litvinko, V. V. Okovity, V. Astashinsky, V. M. Blumenstein","doi":"10.21122/2227-1031-2023-22-3-179-185","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-3-179-185","url":null,"abstract":"In the work, taking into account the state of the issue in the field of applying multilayer heat-shielding and wear-resistant coatings, directions of research are substantiated. The objectives of the development are: improvement of powder materials containing zirconium dioxide partially stabilized with yttrium oxide for plasma deposition of heat-shielding coa-tings; improvement of powder materials containing oxide ceramics and nickel-based alloys for plasma deposition of wear-resistant coatings; development of technological parameters of plasma spraying and subsequent processing by the effects of compression plasma on the coating; analysis of the quality of protective coatings obtained using the optimal technology by studying their structure and physical and mechanical properties. The ZrO2 – 7 % Y2O3 particles contain the predominant tetragonal Y0.15Zr0.85O0.93 phase, monoclinic and cubic ZrO2 phases, and the Al2O3–TiO2–Ni–Cr–Al–Y–Ta composition contains the Cr1.12Ni2.88 phase of the nickel-based solid solution, the a-Al2O3, g-Al2O3 phases, and the orthorhombic phase of titanium oxide TiO2 that contribute to its wear resistance. subsequent optimization of technological parameters for the process of plasma spraying of multilayer heat-shielding and wear-resistant coatings. Technological parameters for the process of plasma spraying of multi-layer heat-shielding and wear-resistant coatings are investigated with subsequent optimization. The optimization criteria were the utilization factor of the sprayed powder material and the structure of the coatings. The influence of the spraying distance on the values of operational characteristics of the formed plasma coatings on Al2O3–TiO2–Ni–Cr–Al–Y–Ta has been studied. The obtained results of controlling the phase composition of coatings by varying the chemical composition of powder materials are presented. In the process of deposition, the differences in the phase composition of the formed material are the more significant, the more inhomogeneous the distribution of elements in the initial powder material. Tests have been carried out for cyclic testing in an oven at a maximum temperature within 1300 °C of heat-shielding coatings to determine their heat resistance. They proved the influence of the phase composition of the formed coatings on their ability to withstand high-temperature oxidation.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122705073","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 : 2023-04-06DOI: 10.21122/2227-1031-2023-22-2-113-118
N. M. Selivonchik, N. L. Nesterenko
To carry out a power calculation of the anti-driveaway device (AD) of lifting cranes operating in the open air, it is necessary to know the conditions that ensure their reliable stop and fixation on rails, as well as kinematic parameters, namely, the speed and acceleration of cranes when they move along the rails under the influence of the wind force. The considered AD for stopping cranes driven away by the force of the wind uses a tong gripper driven by an eccentric mechanism.The paper presents the calculation of the forces arising during the operation of the tong gripper, considering the possibilities of various types of friction on the contact surfaces both in the absence of lubrication and in its presence. The calculations of the eccentric mechanism as one of the fundamental mechanisms of the anti-driveaway crane device are presented in the paper. The stronger the wind force, the more due to the kinematic connection of the two mechanisms, when turning the eccentric mechanism, the pressure of the tong mechanism increases on the side faces of the head of the crane rail. The constructive solution of the AD excludes any actions of the personnel and makes it automatic.
{"title":"Power Calculation of Anti-Driveaway Crane Device from Eccentric and Wedge Mechanisms","authors":"N. M. Selivonchik, N. L. Nesterenko","doi":"10.21122/2227-1031-2023-22-2-113-118","DOIUrl":"https://doi.org/10.21122/2227-1031-2023-22-2-113-118","url":null,"abstract":"To carry out a power calculation of the anti-driveaway device (AD) of lifting cranes operating in the open air, it is necessary to know the conditions that ensure their reliable stop and fixation on rails, as well as kinematic parameters, namely, the speed and acceleration of cranes when they move along the rails under the influence of the wind force. The considered AD for stopping cranes driven away by the force of the wind uses a tong gripper driven by an eccentric mechanism.The paper presents the calculation of the forces arising during the operation of the tong gripper, considering the possibilities of various types of friction on the contact surfaces both in the absence of lubrication and in its presence. The calculations of the eccentric mechanism as one of the fundamental mechanisms of the anti-driveaway crane device are presented in the paper. The stronger the wind force, the more due to the kinematic connection of the two mechanisms, when turning the eccentric mechanism, the pressure of the tong mechanism increases on the side faces of the head of the crane rail. The constructive solution of the AD excludes any actions of the personnel and makes it automatic.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115155887","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 : 2023-04-06DOI: 10.21122/2227-1031-2023-22-2-119-126
Spatial cardan mechanisms designed to transmit rotational motion between shafts, having angular displacement, differ in a variety of design solutions. Cardan gears are an articulation of one or more universal joints and tubular shafts. They compensate for axial movements, and also transmit torque at constant or variable angles between the connected units. During operation, the cardan transmission must function satisfactorily during the established service life, i. e., meet all the requirements arising from the peculiarities of its use. Therefore, the problem of improving cardan gears, increasing their reliability and ergonomicity on the basis of new design solutions optimized for dynamic parameters, materials used, manufacturing, assembly and operation technologies is relevant for modern technology. The paper presents a systematic approach to the creation of a new generation of cardan gears based on research in the field of operating conditions, materials science, materials technology, optimal design. It is shown that according to the results of the research, a new series of gimbal gears with improved technical characteristics has been created.
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Pub Date : 2023-04-06DOI: 10.21122/2227-1031-2023-22-2-150-157
The paper presents the comparative characteristics of the most common modes of heat and moisture treatment (HMT), their advantages and disadvantages, as well as proposals for optimizing the HMT stages to obtain the maximum effect of accelerating concrete hardening through the use of thermal energy. Heat and moisture treatment of concrete is one of the most difficult stages in the technology of prefabricated and monolithic concrete. The basis for the durability of structures, their uninterrupted service during the design period of operation is a properly selected HMT mode, which improves the quality of products and reduces material costs in the form of a reduction in energy costs. Therefore, the still practiced simplified methods for selecting the HMT mode are unacceptable. Only under the condition of strict and scientifically substantiated consideration of a complex of factors influencing the ongoing processes of formation of the structure of cement stone and concrete, and the interaction between them, it is possible to obtain concrete with the required characteristics. Depending on the requirements for the finished material, based on knowledge of the mechanism of heat and mass transfer, rational methods and modes of heat treatment of concrete and reinforced concrete products can be calculated. A variety of HMT modes is due to the desire to reduce the possibility of defects in the concrete structure (for example, modes with a stepped or curvilinear temperature increase, which reduces the temperature gradient across the product section), to reduce energy costs (modes with the exclusion of the isothermal holding stage), etc. In the process of HMT of concrete and reinforced concrete products, a number of chemical and physical transformations of the concrete mixture (concrete) occur, as a result of which various defects in the structure of the material may appear, which worsen its properties (strength, permeability, shrinkage, creep and, in general, durability of concrete). Modern technology for the production of concrete and reinforced concrete products and structures provides for the introduction of various chemical additives, their effect on the hardening of concrete at elevated temperatures, unfortunately, is not sufficiently reflected in the specialized literature. For example, the duration of the total cycle of concrete HMT when using chemical additives – hardening accelerators can be reduced by reducing the periods of preliminary exposure, temperature rise and the duration of isothermal exposure; and the use of plasticizers, depending on their type and content, can lead to a lengthening of the cycle. It is necessary to have analytical dependencies for calculating HMT modes and a computer model of the concrete hardening process at elevated temperatures.
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Pub Date : 2023-04-06DOI: 10.21122/2227-1031-2023-22-2-141-149
The paper investigates the results of solving spatial contact problems on the free support of bending rods (hereinafter referred to as beams) on elastic quarter-space and octant of space. The objectives of the study include determining the stress state of contact pads, obtaining a picture of the distribution of contact stresses over them, and studying the features that arise when solving these contact problems. The main solution method is the method of B. N. Zhemochkin, based on the discretization of contact areas by replacing a continuous contact with a point one. This approach allows us to reduce the contact problem to the calculation of a statically indeterminate system using well-developed methods of structural mechanics. The mathematical model of the contact problems to be solved is built on the assumption of linear elastic (geometric and physical linearity) work of both the bending element and the elastic foundation. Since in the process of deformation the end sections of the beam element can break away from the support areas, the contact problems to be solved belong to the group of contact problems with a previously unknown contact area. The design schemes of such problems are constructively nonlinear, and their calculation is carried out by iterative methods. Based on the results of solving the considered contact problems, it has been found that with a geometrically symmetrical support of the beam element on the left and right on elastic quarter-spaces (space octants) with equal support areas, but different mechanical characteristics, as well as symmetrical loading, the values of support reactions, considering them as resultants of contact stresses on the left and right contact pads, and the coordinates of the points of their application are not equal to each other. The solution of the contact problem leads to a similar result in the case of a bending beam element resting on the elastic quarter-space on one side, and on the edge of the space octant on the other. In addition, a constant torque appears along the entire length of the beam element, indicating that the beam element is in a torsional transverse bending condition.
本文研究了弹性四分之一空间和八分空间上弯曲杆(以下简称梁)自由支承空间接触问题的求解结果。研究的目标包括确定接触垫的应力状态，获得接触应力分布的图像，并研究在解决这些接触问题时出现的特征。主要的求解方法是B. N. Zhemochkin方法，该方法基于接触面积的离散化，将连续接触替换为点接触。这种方法使我们能够将接触问题简化为使用成熟的结构力学方法计算静定系统。所要解决的接触问题的数学模型是建立在弯曲单元和弹性基础的线弹性(几何和物理线性)作用的假设之上的。由于梁单元在变形过程中端部可能脱离支承区域，因此所要解决的接触问题属于接触区域未知的接触问题。这类问题的设计方案是构造非线性的，其计算采用迭代法进行。根据所考虑的接触问题的求解结果发现，当梁单元在几何对称的左右弹性四分之一空间(空间八分空间)上支承面积相等，但力学特性不同，且载荷对称时，将支承反力值考虑为左右接触垫接触应力的结果;它们的应用点的坐标是不相等的。在弯曲梁单元一边位于弹性四分之一空间上，另一边位于空间八分仪边缘的情况下，对接触问题的求解得到了类似的结果。此外，在梁单元的整个长度上出现一个恒定的扭矩，表明梁单元处于扭转横向弯曲状态。
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