Technical mechanics最新文献

{"title":"Features of fastening a swap body on the undercarriage of a freight car","authors":"M. Sobolevska, D. Horobets","doi":"10.15407/itm2023.04.076","DOIUrl":"https://doi.org/10.15407/itm2023.04.076","url":null,"abstract":"Freight car fleet renewal and the introduction of new efficient freight transportation technologies are topical problems of the Ukrainian railway transport. An innovation in the world’s transport service is the use of swap-body freight cars. With seasonal variations in freight shipment, one empty car body can be replaced with another, and the undercarriage with the new body can then be used as a usual dedicated car. It is expedient for Ukraine to develop a swap-body car design of its own. In doing so, special attention must be paid to body-on-undercarriage fasteners. The goal of this paper is to estimate the stress and strain field of swap-body car components and develop recommendations on fasteners that would provide safe freight transportation in swap-body cars according to the Ukrainian State Standard EN 12663-2:2018. The paper considers a swap-body car whose undercarriage is a container flat car and whose body has the dimensions of a 45-feet container; the body mass plus the freight mass is equal to the carrying capacity of the flat car. Previous studies showed that four fitting joints in the presence of clearances therein cannot provide the required swap-body car service strength. The paper analyzes existing designs of body-on-undercarriage fasteners and identifies lines of their improvement: increasing the number of fasteners that transfer service loads from the body to the underframe and using additional grippers for clearance takeup. Finite-element models were developed to study the stress and strain field of swap-body car components at standard loads with account for different schemes of body-on-undercarriage fastening. Using them, it was shown that for the requirements of the Ukrainian State Standard EN 12663-2:2018 to be satisfied, it is sufficient to use eight body-on-undercarriage fitting fasteners with additional elements that make them clearance-free in a longitudinal direction and in a transverse direction on the outside of the underframe. The body-on-undercarriage fastening scheme that minimizes underframe stresses was identified. Recommendations were developed on fasteners that would provide safe freight transportation in swap-body cars.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"9 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138971863","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}

{"title":"Analysis of the state of the art and the trends in the development of the target characteristics of orbital constellations of small agriculture-oriented Earth re-mote sensing spacecraft","authors":"D.O. Khramov, O. Volosheniuk","doi":"10.15407/itm2023.04.031","DOIUrl":"https://doi.org/10.15407/itm2023.04.031","url":null,"abstract":"The goal of this paper is to assess the existing capabilities of orbital constellations of agriculture-oriented Earth remote sensing spacecraft and the prospects for their development in the nearest future. The paper analyzes the state of the art and the trends in the development of modern orbital constellations of private companies’ small Earth remote sensing satellites used in solving agricultural problems. Important sources of information in the space industry, such as NewSpace Index, Gunter's Space Page, and WMO OSCAR, were analyzed. 52 constellations of spacecraft for optical multispectral and hyperspectral, thermal, and microwave (radar) imaging are considered. It is shown that they provide a survey frequency of several times a day. The minimum spatial resolution of optoelectronic surveillance sensors is 1 m (in the panchromatic channel). This allows one to solve problems at an intrafield level, quasi-continuously monitor the plant condition, and use spectral patterns and texture features in solving applied agricultural problems. All the constellations of radar satellites use the X-band, except for the radars of the Spacety constellation (China), which use the C-band. It is shown that the number of constellations of small remote sensing spacecraft in the period 2021–2025 is to be increased by more than three times compared to the period 2016–2020. The number of countries developing constellations of Earth remote sensing satellites has increased significantly. The leading countries and companies in the number and size of constellations are the United States and China and Planet (USA) and Chang Guang Satellite Technology Corporation (China), respectively. Private developers are particularly interested in thermal infrared imaging and hyperspectral optical imaging data. A new line in the private space industry, which is expected to facilitate the solution of agricultural problems, is the deployment of constellations of small meteorological satellites.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"16 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138972124","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}

{"title":"Determination of the kinetic parameters of a supersonic plasma flow of a gas-discharge source from the current measured by an insulated probe system","authors":"D. Lazuchenkov, N. Lazuchenkov","doi":"10.15407/itm2023.04.040","DOIUrl":"https://doi.org/10.15407/itm2023.04.040","url":null,"abstract":"The aim of this work is to develop a procedure for determining the kinetic parameters of charged particles in a supersonic jet of a gas-discharge source of collisionless plasma by measuring the current collected by an insulated probe system of cylindrical electrodes placed transversely to the jet. Based on the authors’ mathematical model of current collection by the above-mentioned probe system and asymptotic solution for the probe current in the electron saturation region, the ion temperature and directed velocity and the electron temperature are related to the measured probe current. The effect of the probe system parameters and the current and voltage measurment error on the reliability of diagnostics of a diatomic gas-discharge plasma is studied. Within the framework of the probe current collection model for the electron saturation region, numerical and analytical estimates of the errors in determining the kinetic plasma parameters are obtained as a function of the geometric parameters of the probe system, the accuracy of probe current measurement, and the bias potential of the probe relative to the potential of the reference electrode. The measuring-to-reference electrode area ratio and the probe current measurement conditions optimal for adequate estimation of the average kinetic energy and the directed velocity of ions in a supersonic gas-discharge plasma jet are determined. A priori quantitative characteristics of the effect of the probe measurement errors on the reliability of the determination of the charged particle kinetic parameters are given. The reported procedure and estimates of the error in kinetic plasma parameter determination allow one to choose the probe system parameters and estimate the required measurement accuracy when planning and conducting experiments on laboratory plasma diagnostics.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"24 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139002955","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}

{"title":"Features of determining the design parameters of the control system of power spacecraft for contactless power transmission to a space industrial platform","authors":"E. Lapkhanov, O. Palii, D. S. Svorobin","doi":"10.15407/itm2023.04.015","DOIUrl":"https://doi.org/10.15407/itm2023.04.015","url":null,"abstract":"The study of the features of near-Earth space industrialization is a promising line in space science. The scientific development of this line is rather deep, and it is carried out both at a theoretical conceptual level and at an experimental level by trying various technological processes onboard the International Space Station. One of the lines of this concept is the study of the features of designing a power system for a space industrial platform. The power system is of the distributed type, which provides for the combined use of power generation modules onboard the space industrial platform itself and an orbital constellation of power spacecraft. In its turn, the use of power spacecraft with contactless electric power transmission to a space industrial platform is intended for highly power-intensive technological processes. In view of the aforesaid, the goal of this paper is to study the features of controlling the power spacecraft of the distributed power supply system of a space industrial platform in such a way as to provide the synchronization of their operating modes with the operation sequence of the space industrial platform. A power spacecraft’s angular motion controllers are synthesized for a solar battery charging mode, a receiving spacecraft aperture pointing mode, and a waiting mode. Methodological recommendations are given on synthesizing the operation schedules of the power spacecraft of the distributed power supply system in such a way as to provide their synchronization with the operation schedules of the space industrial platform. The design parameters to be chosen in designing spacecraft for contactless power transmission to a space industrial platform are identified.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"20 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138971550","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}

{"title":"Computer simulation of the effect of annular inclusions on the stress concentra-tion in thin-walled cylindrical and conical shells with circular openings","authors":"E.L. Hart, O. O. Semencha","doi":"10.15407/itm2023.04.060","DOIUrl":"https://doi.org/10.15407/itm2023.04.060","url":null,"abstract":"Shell structures are used in various industries, such the aerospace industry, the oil and gas industry, power engineering, mechanical engineering, construction, etc. Due to their design or manufacturing features, their integrity may be disrupted by the presence of various openings, around which local stresses develop. Finding ways to reduce stress concentrations around openings is an important problem in deformable solid mechanics. This paper presents the results of a computer simulation and a finite-element analysis of the stress and strain field of thin-walled cylindrical and truncated conical shells with circular openings in the presence of annular inclusions around them made of a material whose properties differ from the main material of the shells. The effect of the elastic modulus of an inclusion and its geometric parameters on the stress and strain concentration in the vicinity of the openings was studied. Several inclusion materials and inclusion widths were considered. An annular inclusion made of a homogeneous material and located in the shell plane was considered. Stress and strain intensity distributions in the local stress concentration zones were calculated. A comparative analysis of the results obtained for cylindrical and conical shells was carried out. The study showed that the presence of a “soft” homogeneous annular inclusion makes it possible to reduce the stress concentration around the opening by ~13–35% depending on the inclusion width and elastic modulus both for a cylindrical and a conical shell. Certain combinations of the geometric and mechanical parameters of the inclusion give rise to a “mechanical” effect, which consists in shifting the stress concentration zone from the opening edge to the inclusion – shell material interface. For conical shells, due to their geometric features, a “conical” effect occurs: the stresses increase not only in the vicinity of the opening-weakened zone, but also near the cone basis.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"156 20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138973162","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}

{"title":"Algorithms for stabilizing the rotor speed of a Darrieus wind power plant con-trolled by blade length variation","authors":"S.V. Tarasov, O.N. Molotkov","doi":"10.15407/itm2023.04.050","DOIUrl":"https://doi.org/10.15407/itm2023.04.050","url":null,"abstract":"The world’s power engineering features ever increasing attention to the development of renewable power sources. Difficulties in provision with traditional energy sources (gas, coal, and oil products) and the global trends of transition to green sources call for replacing the traditional sources with new ones. Among the alternative energy sources, wind power plants (WPPs) installed in suitable territories have received widespread use. Modern WPPs are of two types: vertical- and horizontal-axis ones. Vertical-axis WPPs, as distinct from horizontal-axis ones, have a number of specific advantages, such as, for example, insensitivity to wind direction changes, which significantly simplify the WPP design and increase the WPP reliability. Both WPP types are dynamically complex systems, which operate in different regimes depending on their dynamic and technological features. The task of matching these features is assigned to control systems, which control the rotor operation using additional devices, for example, generators of different types. For horizontal-axis WPPs, approaches to the solution of a number of system control problems have been developed on the basis of the principle of swept area variation. The development of a similar approach for vertical-axis WPPs seems to be an important and promising task. The goal of this paper is to develop efficient algorithms of WPP rotor speed stabilization using the principle of swept area variation, namely, telescopic blades. The problem is solved using methods of the classical automatic control theory and mathematical simulation. The novelty lies in extending the concept of control by swept area variation to Darrieus vertical-axis WPPs, synthesizing efficient algorithms for stabilizing the rotor speed of Darrieus vertical-axis WPPs controlled by blade length variation, and determining conditions for their stability. The algorithms may be used in substantiating design solutions for Darrieus rotor vertical-axis WPPs.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138971759","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}

{"title":"Numerical simulation of a two-phase flow in a jet mill ejector with an additional energy supply","authors":"O.D. Ihnatiev, H. Shevelova","doi":"10.15407/itm2023.04.104","DOIUrl":"https://doi.org/10.15407/itm2023.04.104","url":null,"abstract":"New approaches to the preparation and processing of raw materials in the process of jet grinding are gaining more and more importance. This is due to the need to increase the efficiency of grinding and reduce the energy consumption of the equipment, increase its reliability and service life, and expand the possibility of using the jet mill in various industries. All this determines the importance of developing and implementing new approaches to two-phase flow organization in the channels of a jet mill. The goal of this work is to investigate a method for improving two-phase flow organization in the gas jet mill tracts. Numerical studies of a two-phase flow in the ejector of a jet mill showed the advisability of using an additional energy supply through the walls of the accelerating tube of the ejector to increase the efficiency of its operation. Controlling the gas flows in the mill ejector by using the energy of additional gas flows allows one to speed up the main flow at the exit of the ejector accelerating tube and form a protective layer around the tube walls to prevent their wear. The installation of a conical nozzle at the end of the accelerating tube prevents flow separation and vortex formation and provides a uniform velocity distribution at the ejector exit. The paper presents new solutions and recommendations on improving the efficiency of two-phase flow organization in the ducts of a gas jet mill. The scientific significance of the results lies in the development of a gas-dynamic method for controlling the gas flows in the jet mill tracts, which provides a uniform acceleration of the bulk material particles and reduces mill wear. The practical significance lies in the development of recommendations on increasing the efficiency of two-phase flow organization in the gas jet mill tracts. The results may be used in mining, metal manufacture, construction, the chemical and the food industry, and agriculture, and they will be employed in further development of scientific fundamentals of gas jet mill improvement.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"17 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138974802","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}

{"title":"Wheel profile of a freight car with prospective trucks for the combined operation on the Ukrainian and European railways","authors":"T. Mokrii, I. Malysheva, S.S. Pasichyk","doi":"10.15407/itm2023.04.090","DOIUrl":"https://doi.org/10.15407/itm2023.04.090","url":null,"abstract":"To solve the important problem of speeding up the integration of Ukraine into the European railway transportation, an interest has recently grown in the introduction of automatic car transfer from one track gauge to another using gauge-changeable wheelsets, thus dispensing with truck exchange or transshipment and thereby significantly shortening the delivery time. However, the combined operation of trains on the Ukrainian (1,520 mm gauge) and European (1,435 mm gauge) railways calls for the compatibility of the wheel-rail contact pair on both railways: R65 rails and a cant of 1/20 in Ukraine and UIC60 rails and a cant of 1/40 in Europe. The goal of this work is to develop a wheel profile for a freight car with prospective 18-7020 trucks for combined operation on the Ukrainian and European railways and predict the ride performance of a car with that wheel profile and its dynamic interaction with rails on both railways. An investigation was conducted into the wheel?rail interaction indices and the ride performance of a freight car with prospective 18-7020 trucks and wheels with existing profiles. It was shown that it is expedient to develop a new wheel profile to improve the service compatibility of the Ukrainian and European networks. A number of new wheel profiles were constructed, the efficiency of each profile in terms of dynamic stability at service speeds and wheel flange wear on the Ukrainian and European railways was calculated, and a compromise profile, ITM-73ES, was chosen. It was shown that the use of the chosen profile in a car with 18-7020 trucks will offer a high dynamic performance and improved indices of wheel?rail interaction for both truck gauges.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"564 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138974107","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}

{"title":"Mathematical simulation of the stress and strain field of swap-body freight car components at service loads","authors":"M. Sobolevska, D. Horobets","doi":"10.15407/itm2023.02.091","DOIUrl":"https://doi.org/10.15407/itm2023.02.091","url":null,"abstract":"A new line in railway transportation is the use of swap-body freight cars. Their undercarriage is a flat car for swap bodies, which consists of an underframe, running gear, automatic couples, automatic braking devices, and body fasteners. With seasonal variations in freight shipment, the same flat cars can be used because empty bodies of one purpose are detached from the flat cars and replaced with bodies of another purpose, thus making it possible to use the freight cars obtained in this way dedicated ones. The advantage of freight transportation with swap-body cars is that it allows one to reduce the car acquisition and maintenance cost due to the effective use of a flat car as the most expensive part of a freight car, avoid car demurrage caused by seasonal variations in freight shipment, and speed up the replacement of damaged bodies. It is expedient to introduce freight transportation with swap-body cars on the Ukrainian railways using the world’s experience in the development of swap-body cars. This paper considers a swap-body freight car whose undercarriage is a container flat car. The goal of the paper is a mathematical simulation of the stress and strain field of the components of a swap-body freight car at standard loads according to the Ukrainian State Standard EN 12663-2:2018. Finite-element models were developed to study the stress and strain field of the components of a 45-feet container flat car and a swap-body car at standard loads with account for the features of body-on-undercarriage fastening and clearances in the fasteners. The models underlie the scientific novelty of the paper. Using them, the stress and strain field of the car components at standard loads was studied. According to the requirements of the Ukrainian State Standard EN 12663-2:2018, the strength of the structural components of the flat car underframe was estimated under different loading conditions. It was found that the strength of the 45-feet container flat car underframe under study meets requirements of the Ukrainian State Standard EN 12663-2:2018, while the strength of the underframe of the swap-body car undercarriage does not. This study evidences the need to strengthen the body-on-undercarriage fasteners and improve the design of the swap-body car underframe itself.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115730172","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}

{"title":"Determination of the electron temperature in a supersonic jet of a gas-discharge source from current measurements by an insulated probe system","authors":"D. Lazuchenkov","doi":"10.15407/itm2023.02.074","DOIUrl":"https://doi.org/10.15407/itm2023.02.074","url":null,"abstract":"The aim of this work is to substantiate the possibility of using the classical procedure for determining the electron temperature for diagnosing a supersonic jet of a collisionless plasma of a diatomic gas using the current-voltage characteristic of an insulated probe system. The probe system consists of a cylindrical probe and a reference electrode composed of several cylinders, all placed transversely in the plasma flow. The ratio of the current-collecting surface area of the reference electrode to the area of the probe is arbitrary and can be significantly less than required by the theory of a single probe. Based on a previously constructed mathematical model of current collection, which includes the calculation of the equilibrium potential of the reference electrode as a function of the probe bias voltage, a procedure is developed for determining the electron temperature by measuring the probe currents in a jet of a gas-discharge source of a laboratory dissociated plasma. An approximation of the floating potential of the insulated probe system in a strongly nonequilibrium plasma of a gas-discharge source jet is found, which allows one to determine the boundaries of the transition region of the current-voltage characteristic using a priori information on the plasma parameters. A formula is obtained for extrapolating the ion probe current vs. bias potential relationship into the transition region of the current-voltage characteristic. Within the framework of the adopted mathematical model of charged plasma particle collection, a numerical analysis of the method error of the electron temperature determination procedure is performed. Quantitative characteristics of the effect of the insulated probe system geometry on the method error are obtained. A numerical simulation of the effect of the probe current measurement errors showed that, within the framework of the adopted model, the accuracy of determining the electron temperature using the insulated probe system is comparable with the accuracy of measurements with a single cylindrical probe. The results obtained may be used in the diagnostics of a laboratory plasma of a gas-discharge source.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"248 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114250683","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}