An urgent task for Ukraine during the post-war reconstruction of the country will be the upgrade of the entire railway transportation system, in particular the development of high-speed passenger traffic. The prediction of the dynamic performance of high-speed rail vehicles calls for the formation of new input arrays (track-induced disturbances) that would account for more stringent track geometry requirements. The aim of this work is to study the possibility of using track irregularities recorded in real sections of the Ukrainian railways to construct the components of track-induced disturbances acting on a rail vehicle moving at a high speed. This paper considers in detail standard specifications for the geometric parameters of a track suitable for high-speed traffic. The data are contained in the Standard DSTU EN 13848-5:2018, which is a European standard adopted in Ukraine as a national one by confirmation. Using the track subsidence and alignment irregularities recorded by a track measurement car in a number of sections of the Pryndiprovska railway during a scheduled track inspection, processes of actual vertical and horizontal irregularities were formed. The quality of those sections had not require any speed limitation. Irregularity parameters for those sections were calculated. A comparison between the calculated parameters and those specified by the DSTU EN 13848-5:2018 showed that among the sections considered there exist ones that meet the track geometry requirements and allow speeds at least up to 230 km/h. The use of the irregularities in the selected track sections as disturbance components in calculations was tested by the example of determining the ride performance of a standard passenger car with KVZ-TsNII-M trucks. The calculated results showed the possibility of using the generated disturbances in numerical calculations of the dynamic performance of rail vehicles at increased speeds and at the same time confirmed the need for new engineering solutions on the design of rail vehicles capable of operating at such speeds.
乌克兰在战后重建期间的一项紧迫任务将是升级整个铁路运输系统，特别是发展高速客运。高速铁路车辆动态性能的预测需要形成新的输入阵列(轨道诱导扰动)，这将满足更严格的轨道几何要求。这项工作的目的是研究利用在乌克兰铁路实际路段记录的轨道不规则性来构建作用于高速行驶的轨道车辆的轨道诱导干扰的组成部分的可能性。本文详细讨论了适用于高速交通的轨道几何参数的标准规范。数据包含在标准DSTU EN 13848-5:2018中，该标准是乌克兰通过确认采用的欧洲标准。利用轨道测量车在定期轨道检查期间在Pryndiprovska铁路的多个路段记录的轨道沉降和路线不规则性，形成了实际垂直和水平不规则性的过程。这些路段的质量不需要任何速度限制。计算了这些截面的不规则参数。计算参数与DSTU EN 13848-5:2018规定的参数之间的比较表明，在考虑的路段中，存在满足轨道几何要求并允许速度至少达到230公里/小时的路段。以KVZ-TsNII-M型卡车的标准客车行驶性能为例，验证了在计算中使用所选轨道段中的不规则性作为干扰分量。计算结果表明，利用所产生的扰动进行高速轨道车辆动力性能数值计算的可能性，同时也证实了在高速轨道车辆设计上需要新的工程解决方案。
{"title":"Study of the possibility of using disturbances formed from recorded track irregularities in the calculation of high-speed rail vehicle dynamics","authors":"L. Lapina, I. Malysheva, T. Mokrii","doi":"10.15407/itm2022.02.115","DOIUrl":"https://doi.org/10.15407/itm2022.02.115","url":null,"abstract":"An urgent task for Ukraine during the post-war reconstruction of the country will be the upgrade of the entire railway transportation system, in particular the development of high-speed passenger traffic. The prediction of the dynamic performance of high-speed rail vehicles calls for the formation of new input arrays (track-induced disturbances) that would account for more stringent track geometry requirements. The aim of this work is to study the possibility of using track irregularities recorded in real sections of the Ukrainian railways to construct the components of track-induced disturbances acting on a rail vehicle moving at a high speed. This paper considers in detail standard specifications for the geometric parameters of a track suitable for high-speed traffic. The data are contained in the Standard DSTU EN 13848-5:2018, which is a European standard adopted in Ukraine as a national one by confirmation. Using the track subsidence and alignment irregularities recorded by a track measurement car in a number of sections of the Pryndiprovska railway during a scheduled track inspection, processes of actual vertical and horizontal irregularities were formed. The quality of those sections had not require any speed limitation. Irregularity parameters for those sections were calculated. A comparison between the calculated parameters and those specified by the DSTU EN 13848-5:2018 showed that among the sections considered there exist ones that meet the track geometry requirements and allow speeds at least up to 230 km/h. The use of the irregularities in the selected track sections as disturbance components in calculations was tested by the example of determining the ride performance of a standard passenger car with KVZ-TsNII-M trucks. The calculated results showed the possibility of using the generated disturbances in numerical calculations of the dynamic performance of rail vehicles at increased speeds and at the same time confirmed the need for new engineering solutions on the design of rail vehicles capable of operating at such speeds.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"175 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114752390","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}
The purpose of this article is to develop a classifier and classification of technological processes in space to implement them on a space industrial platform. In the nearest future, mankind may face global challenges, first of all, the global warming problem and the problem of limited terrestrial resources. One of the obvious solutions to these problems is the industrialization of near space first and deep space and celestial bodies in the future. The initial stage of space industrialization is the construction of space industrial platforms in Earth orbits. The problem of space industrial platform construction is many-sided and requires various information. Currently, there exist works that are concerned to some extent or anther with the implementation of a number of technological processes in space, which are studied by scientists and developers in the relevant fields. Implemented in space, unique technological processes allow one to obtain materials with qualitatively new characteristics. The article presents a set of criteria for the classification of technological processes in space, a classifier developed on their basis for the classification of the processes in terms of their implementation on a space industrial platform, an analysis of technological processes to be implemented in space, and a set of their parameters to be provided on the platform. Using the classifier, functional diagrams of various technological processes implementable in near space are analyzed. The functional diagrams contain basic and auxiliary modules according to the process type. A relationship between the process and basic parameters of an industrial platform is shown. The freight flow, the communication and control channels, the power supply, and the thermal regime, ventilation, and vacuumizing assurance of the platform are determined and shown schematically.
{"title":"Classification of technological processes in terms of their implementation on a space industrial platform","authors":"O. Palii","doi":"10.15407/itm2022.02.123","DOIUrl":"https://doi.org/10.15407/itm2022.02.123","url":null,"abstract":"The purpose of this article is to develop a classifier and classification of technological processes in space to implement them on a space industrial platform. In the nearest future, mankind may face global challenges, first of all, the global warming problem and the problem of limited terrestrial resources. One of the obvious solutions to these problems is the industrialization of near space first and deep space and celestial bodies in the future. The initial stage of space industrialization is the construction of space industrial platforms in Earth orbits. The problem of space industrial platform construction is many-sided and requires various information. Currently, there exist works that are concerned to some extent or anther with the implementation of a number of technological processes in space, which are studied by scientists and developers in the relevant fields. Implemented in space, unique technological processes allow one to obtain materials with qualitatively new characteristics. The article presents a set of criteria for the classification of technological processes in space, a classifier developed on their basis for the classification of the processes in terms of their implementation on a space industrial platform, an analysis of technological processes to be implemented in space, and a set of their parameters to be provided on the platform. Using the classifier, functional diagrams of various technological processes implementable in near space are analyzed. The functional diagrams contain basic and auxiliary modules according to the process type. A relationship between the process and basic parameters of an industrial platform is shown. The freight flow, the communication and control channels, the power supply, and the thermal regime, ventilation, and vacuumizing assurance of the platform are determined and shown schematically.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125718548","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}
The development of competitive space hardware calls for continuing improvements in the accuracy of simulation of gas-dynamic processes in the space vehicle vicinity. This may contribute to extending the active life of spacecraft, thus improving the economic efficiency of space activities. In particular, quite a topical problem is the simulation of the interaction of rarefied jets from the propulsion system of a spacecraft with its individual components. To solve this problem in the case of a rather high surrounding vacuum, use is made of the molecular-kinetic concept of the gas structure based on the Boltzmann equation. The aim of this paper is to overview existing methods of simulation of gas-dynamic processes near spacecraft in a rarefied gas flow with account for propulsion system jets and to choose the most promising approaches to the solution of this problem. Among the methods considered, several main lines are set off: approximate, analytical, and numerical methods. Approximate methods use physical models of jet flow, approximation of numerical results, or a combination of both approaches. Analytical methods are based on essentially simplified assumptions and are intended for a very narrow class of problems. Numerical methods are the most universal tool of theoretical study. At the same time, each numerical method has a range of application of its own. At present, the most used and promising methods are statistical simulation methods: the direct simulation Monte Carlo method (DSMCM) and the test particle method (TPM). The former splits the continuous process of molecule motion and collisions in a rarefied gas into two successive independent stages (free-molecular transfer and relaxation) at each small time step. The simulation is done by time steps and in fact reproduces a nonstationary process. The latter, the TPM, consist in a statistical successive simulation of the wandering of test particles (molecules) on the background of field ones about the cells of the computational grid. Test particles, which move within the cells of the computational area, periodically collide with the obstacle in the flow and field particles, and in doing so they gradually change both their velocity and the field characteristics. For both statistical approaches, the simulation accuracy, as can be expected, is inversely proportional to the square root of the number of tests: the number of time steps and modeling particles for the DSMCM and the number of successively simulated test particle trajectories for the TPM. This may greatly affect the possibility of attaining a desired accuracy.
{"title":"Numerical gas-dynamic computational methods in problems of rarefied jet flow about obstacles","authors":"T.G. Smila, L. Pecherytsia","doi":"10.15407/itm2022.02.071","DOIUrl":"https://doi.org/10.15407/itm2022.02.071","url":null,"abstract":"The development of competitive space hardware calls for continuing improvements in the accuracy of simulation of gas-dynamic processes in the space vehicle vicinity. This may contribute to extending the active life of spacecraft, thus improving the economic efficiency of space activities. In particular, quite a topical problem is the simulation of the interaction of rarefied jets from the propulsion system of a spacecraft with its individual components. To solve this problem in the case of a rather high surrounding vacuum, use is made of the molecular-kinetic concept of the gas structure based on the Boltzmann equation. The aim of this paper is to overview existing methods of simulation of gas-dynamic processes near spacecraft in a rarefied gas flow with account for propulsion system jets and to choose the most promising approaches to the solution of this problem. Among the methods considered, several main lines are set off: approximate, analytical, and numerical methods. Approximate methods use physical models of jet flow, approximation of numerical results, or a combination of both approaches. Analytical methods are based on essentially simplified assumptions and are intended for a very narrow class of problems. Numerical methods are the most universal tool of theoretical study. At the same time, each numerical method has a range of application of its own. At present, the most used and promising methods are statistical simulation methods: the direct simulation Monte Carlo method (DSMCM) and the test particle method (TPM). The former splits the continuous process of molecule motion and collisions in a rarefied gas into two successive independent stages (free-molecular transfer and relaxation) at each small time step. The simulation is done by time steps and in fact reproduces a nonstationary process. The latter, the TPM, consist in a statistical successive simulation of the wandering of test particles (molecules) on the background of field ones about the cells of the computational grid. Test particles, which move within the cells of the computational area, periodically collide with the obstacle in the flow and field particles, and in doing so they gradually change both their velocity and the field characteristics. For both statistical approaches, the simulation accuracy, as can be expected, is inversely proportional to the square root of the number of tests: the number of time steps and modeling particles for the DSMCM and the number of successively simulated test particle trajectories for the TPM. This may greatly affect the possibility of attaining a desired accuracy.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114514934","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}
O. Ihnatiev, N. Pryadko, G. Strelnikov, K. Ternova
Flow in a truncated supersonic Laval nozzle with a bell-shaped tip (“bell”) is investigated. This nozzle configuration can be used in tight layouts of multistage rockets of short length with improved energy-mass characteristics. Similar types of nozzles were developed at the Institute of Technical Mechanics of the National Academy of Sciences and the State Space Agency of Ukraine in the 1990s. Using approximate methods, the parameters of variously configured truncated nozzles were calculated, and their models were made. Some of the models were blown with cold air, and their characteristics were measured. Shadow patterns of gas flow downstream of the nozzle and soot-oil patterns of streamlines on the nozzle wall were obtained. These results were used in the formulation of this work. In this work, a numerical study with the ANSYS package was carried out for gas flow in a truncated Laval nozzle with a spherical tip. For this nozzle configuration, its model was blown with cold air. The calculated results were verified by comparing the velocity distribution in the gas flow downstream of the nozzle exit with the experimental shadow patterns. An additional confirmation of the correctness of the calculated results was a comparison of the flow downstream of a streamline-profiled Laval nozzle with the underexpanded flow pattern downstream of the nozzle exit in the first “cask” (up to the Mach disk) studied in detail. The same initial data and initial conditions that give the best results in terms of verifiability were chosen in both cases. The study of flow in a truncated supersonic nozzle showed the following results. Downstream of the corner exit point of the truncated section of a Laval nozzle, flow separation is observed where the gas flow enters the “bell”. The separation is retained as the pressure upstream of the nozzle increases up to a certain critical (for a given tip type) value of the underexpansion ratio, after which (with a further increase in the underexpansion ratio) the flow attaches to the nozzle wall and remains attached with a further increase in the pressure upstream of the nozzle. The impulse response of a truncated nozzle with a bell-shaped tip is lower than that of a streamline-profiled Laval nozzle of the same geometric expansion ratio.
{"title":"Gas flow in a truncated Laval nozzle with a bell-shaped tip","authors":"O. Ihnatiev, N. Pryadko, G. Strelnikov, K. Ternova","doi":"10.15407/itm2022.02.039","DOIUrl":"https://doi.org/10.15407/itm2022.02.039","url":null,"abstract":"Flow in a truncated supersonic Laval nozzle with a bell-shaped tip (“bell”) is investigated. This nozzle configuration can be used in tight layouts of multistage rockets of short length with improved energy-mass characteristics. Similar types of nozzles were developed at the Institute of Technical Mechanics of the National Academy of Sciences and the State Space Agency of Ukraine in the 1990s. Using approximate methods, the parameters of variously configured truncated nozzles were calculated, and their models were made. Some of the models were blown with cold air, and their characteristics were measured. Shadow patterns of gas flow downstream of the nozzle and soot-oil patterns of streamlines on the nozzle wall were obtained. These results were used in the formulation of this work. In this work, a numerical study with the ANSYS package was carried out for gas flow in a truncated Laval nozzle with a spherical tip. For this nozzle configuration, its model was blown with cold air. The calculated results were verified by comparing the velocity distribution in the gas flow downstream of the nozzle exit with the experimental shadow patterns. An additional confirmation of the correctness of the calculated results was a comparison of the flow downstream of a streamline-profiled Laval nozzle with the underexpanded flow pattern downstream of the nozzle exit in the first “cask” (up to the Mach disk) studied in detail. The same initial data and initial conditions that give the best results in terms of verifiability were chosen in both cases. The study of flow in a truncated supersonic nozzle showed the following results. Downstream of the corner exit point of the truncated section of a Laval nozzle, flow separation is observed where the gas flow enters the “bell”. The separation is retained as the pressure upstream of the nozzle increases up to a certain critical (for a given tip type) value of the underexpansion ratio, after which (with a further increase in the underexpansion ratio) the flow attaches to the nozzle wall and remains attached with a further increase in the pressure upstream of the nozzle. The impulse response of a truncated nozzle with a bell-shaped tip is lower than that of a streamline-profiled Laval nozzle of the same geometric expansion ratio.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133665860","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}
This work is devoted to the development of procedures for the aerodynamic improvement of gas-turbine engine axial-flow compressor blade rows. The aim of the work is to compare the efficiency of two methods for impeller blade shape variation in the aerodynamic improvement of an aircraft gas-turbine engine two-stage fan. The first method consists only in varying the blade profile angle along the blade height, while the second consists in varying the blade profile angle and geometrical parameters. The features of the approach used in the solution of this problem are as follows: formulating quality criteria as the mean integral values of the power characteristics of each impeller of the fan over the operating range of the air flow rate through the impeller and searching for advisable values of the impeller blade parameters by scanning the independent variable range at points that form a uniformly distributed sequence of small length. The basic tool is a numerical method developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, which simulates 3D turbulent gas flows in the compressor stage blade channels using the complete averaged Navier¬–Stokes equations. The results of multiparameter calculations of 3D turbulent gas flows show that at the initial stage of the aerodynamic improvement of compressor blade rows varying the blade profile angle alone is more efficient; however, increasing the number of elements of the uniformly distributed sequence of points in the variable range increases the possibility of finding a point at which the blade profile aerodynamic characteristics significantly improve. The results obtained are expected to be used in the aerodynamic improvement of gas-turbine engine compressor blade rows.
{"title":"Features of blade shape variation in the aerodynamic improvement of aircraft gas-turbine engine compressors","authors":"Y. Kvasha, N. Zinevych, N. V. Petrushenko","doi":"10.15407/itm2022.02.017","DOIUrl":"https://doi.org/10.15407/itm2022.02.017","url":null,"abstract":"This work is devoted to the development of procedures for the aerodynamic improvement of gas-turbine engine axial-flow compressor blade rows. The aim of the work is to compare the efficiency of two methods for impeller blade shape variation in the aerodynamic improvement of an aircraft gas-turbine engine two-stage fan. The first method consists only in varying the blade profile angle along the blade height, while the second consists in varying the blade profile angle and geometrical parameters. The features of the approach used in the solution of this problem are as follows: formulating quality criteria as the mean integral values of the power characteristics of each impeller of the fan over the operating range of the air flow rate through the impeller and searching for advisable values of the impeller blade parameters by scanning the independent variable range at points that form a uniformly distributed sequence of small length. The basic tool is a numerical method developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, which simulates 3D turbulent gas flows in the compressor stage blade channels using the complete averaged Navier¬–Stokes equations. The results of multiparameter calculations of 3D turbulent gas flows show that at the initial stage of the aerodynamic improvement of compressor blade rows varying the blade profile angle alone is more efficient; however, increasing the number of elements of the uniformly distributed sequence of points in the variable range increases the possibility of finding a point at which the blade profile aerodynamic characteristics significantly improve. The results obtained are expected to be used in the aerodynamic improvement of gas-turbine engine compressor blade rows.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132325707","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}
High-speed multiple-unit trains in Ukraine must be developed according to the Ukrainian Standards DSTU EN 12663 and DSTU EN 15227, which specify the car crashworthiness and active and passive safety. This paper addresses issues involving the development of recommendations on the passive safety of a multiple-unit head car in emergency collisions with obstacles, the determination of the parameters of the energy-absorbing devices (EADs) that are a part of the passive safety system (PSS) of the head car, and the possibility of using aluminum alloys in the EAD manufacturing. Researchers of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine developed a passive protection concept for home high-speed passenger trains in emergency collisions according to the DSTU EN 15227 requirements and methods and finite-element models for the study of the impact plastic deformation of the EAD honeycomb structures. It was proposed that lower- and upper-level energy-absorbing devices EAD 1 and UL EAD, respectively, be used at head car front end and low-level energy-absorbing devices be used at the head car rear end in place of buffers (EAD 2 or EAD 3 if the intermediate cars have a mass of 50 t or 64 t, respectively). EAD 1 includes two tandem elements. Element 1 is a box with a single-layer pack of hexagonal honeycombs inside. Element 2 is a truncated pyramid made up of honeycombs with triangular cells. The UL EAD has three stages in the form of Element 2. EAD 2 and EAD 3 were designed based on Element 1. The parameters of EAD 1, EAD 2, and EAD 3 of energy capacity 0.95 MJ, 0.25 MJ, and 0.3 MJ, respectively, made of type 08Yu steel were determined. A 3D geometrical model of the home head car front end was developed, and an EAD placement scheme was proposed. It was recommended to install two EAD 1 devices at the head car front end and two UL EAD and two EAD 2 or two EAD 3 devices at the head car rear end and at the ends of the intermediate cars. The aim of this paper is to develop recommendations on manufacturing head car passive protection devices with the use of different materials. A comprehensive study was conducted to choose advisable parameters of a UL EAD made of 08Yu steel and to analyze the possibility of replacing 08Yu steel in the EAD 1, EAD 2 (EAD 3), and UL EAD manufacture with AMr2 and AMr6 aluminum alloys, which have high plastic properties, a low density, and a high resistance to an aggressive environment. As a result, it was shown that 08Yu steel can be replaced with AMr6 aluminum alloy in the EAD 1 and EAD 3 manufacture and with AMr6 or AMr2 aluminum alloys in the UL EAD manufacture. The parameters of the above-mentioned EADs made of the aluminum allows were determined. Recommendations on head car passive protection according to the DSTU EN 15227 were developed. The methods, mathematical models, and recommendations developed may be used in the design of a new-generation head car acc
乌克兰的高速多单元列车必须按照乌克兰标准DSTU EN 12663和DSTU EN 15227开发，这些标准规定了汽车的耐撞性和主动和被动安全性。本文讨论的问题涉及多单元头车紧急碰撞时被动安全建议的发展，头车被动安全系统(PSS)一部分吸能装置(EADs)参数的确定，以及在EAD制造中使用铝合金的可能性。乌克兰国家科学院技术力学研究所和乌克兰国家航天局的研究人员根据DSTU EN 15227的要求和研究EAD蜂窝结构冲击塑性变形的方法和有限元模型，开发了用于紧急碰撞的国内高速客运列车的被动保护概念。建议在车头前端分别采用下、上能级吸能装置EAD 1和UL EAD，在车头后端采用低能级吸能装置代替缓冲器(中间车质量分别为50t和64t时采用EAD 2或EAD 3)。EAD 1包括两个串联元件。元素1是一个盒子，里面有单层的六边形蜂巢。元素2是由带有三角形单元的蜂窝组成的截形金字塔。UL EAD以元素2的形式分为三个阶段。EAD 2和EAD 3是基于Element 1设计的。测定了以08Yu钢为材料，能量容量分别为0.95 MJ、0.25 MJ和0.3 MJ时的EAD 1、EAD 2和EAD 3参数。建立了主头车前端的三维几何模型，提出了EAD的定位方案。建议在车头车头前端安装2个EAD 1装置，在车头车头后端和中间车尾部安装2个UL EAD和2个EAD 2或2个EAD 3装置。本文的目的是提出使用不同材料制造头部汽车被动保护装置的建议。通过对08Yu钢制造的UL EAD的合理参数选择进行了全面的研究，并分析了用AMr2和AMr6铝合金代替08Yu钢制造EAD 1、EAD 2 (EAD 3)和UL EAD的可能性。AMr2和AMr6铝合金具有高塑性、低密度和高抗腐蚀性。结果表明，08Yu钢在EAD 1和EAD 3制造中可以用AMr6铝合金代替，在UL EAD制造中可以用AMr6或AMr2铝合金代替。确定了上述用铝型材制成的EADs的参数。根据DSTU EN 15227制定了车头被动防护的建议。所开发的方法、数学模型和建议可用于根据DSTU EN 15227要求设计新一代头车。
{"title":"Recommendations on manufacturing head car passive protection devices with the use of different materials","authors":"M. Sobolevska, D. Horobets","doi":"10.15407/itm2022.02.101","DOIUrl":"https://doi.org/10.15407/itm2022.02.101","url":null,"abstract":"High-speed multiple-unit trains in Ukraine must be developed according to the Ukrainian Standards DSTU EN 12663 and DSTU EN 15227, which specify the car crashworthiness and active and passive safety. This paper addresses issues involving the development of recommendations on the passive safety of a multiple-unit head car in emergency collisions with obstacles, the determination of the parameters of the energy-absorbing devices (EADs) that are a part of the passive safety system (PSS) of the head car, and the possibility of using aluminum alloys in the EAD manufacturing. Researchers of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine developed a passive protection concept for home high-speed passenger trains in emergency collisions according to the DSTU EN 15227 requirements and methods and finite-element models for the study of the impact plastic deformation of the EAD honeycomb structures. It was proposed that lower- and upper-level energy-absorbing devices EAD 1 and UL EAD, respectively, be used at head car front end and low-level energy-absorbing devices be used at the head car rear end in place of buffers (EAD 2 or EAD 3 if the intermediate cars have a mass of 50 t or 64 t, respectively). EAD 1 includes two tandem elements. Element 1 is a box with a single-layer pack of hexagonal honeycombs inside. Element 2 is a truncated pyramid made up of honeycombs with triangular cells. The UL EAD has three stages in the form of Element 2. EAD 2 and EAD 3 were designed based on Element 1. The parameters of EAD 1, EAD 2, and EAD 3 of energy capacity 0.95 MJ, 0.25 MJ, and 0.3 MJ, respectively, made of type 08Yu steel were determined. A 3D geometrical model of the home head car front end was developed, and an EAD placement scheme was proposed. It was recommended to install two EAD 1 devices at the head car front end and two UL EAD and two EAD 2 or two EAD 3 devices at the head car rear end and at the ends of the intermediate cars. The aim of this paper is to develop recommendations on manufacturing head car passive protection devices with the use of different materials. A comprehensive study was conducted to choose advisable parameters of a UL EAD made of 08Yu steel and to analyze the possibility of replacing 08Yu steel in the EAD 1, EAD 2 (EAD 3), and UL EAD manufacture with AMr2 and AMr6 aluminum alloys, which have high plastic properties, a low density, and a high resistance to an aggressive environment. As a result, it was shown that 08Yu steel can be replaced with AMr6 aluminum alloy in the EAD 1 and EAD 3 manufacture and with AMr6 or AMr2 aluminum alloys in the UL EAD manufacture. The parameters of the above-mentioned EADs made of the aluminum allows were determined. Recommendations on head car passive protection according to the DSTU EN 15227 were developed. The methods, mathematical models, and recommendations developed may be used in the design of a new-generation head car acc","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125533673","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}
This paper presents a nonlinear mathematical model of self-vibrations of conical sandwich shells with a honeycomb core made by additive technologies. The vibrations of the structure are described by fifteen unknowns. Each layer of the structure is described by five unknowns: three projections of the displacements of the layer middle surface and two rotation angles of the middle surface normal. Displacement continuity conditions at the layer interfaces are used. The higher-order shear theory is used to describe the stress-strain state of the structure. The case of conical sandwich shell ? supersonic gas flow interaction is considered. Due to this interaction, self-vibrations of the shell structure are set up. In their analysis, the geometrical nonlinearity of the structure is accounted for. Motion equations of the structure are derived using the assumed-mode method, which uses the kinetic and the potential energy of the structure. The self-vibrations are represented as eigenmode expansions, which contain a set of generalized coordinates. A system of nonlinear autonomous ordinary differential equations in the generalized coordinates is derived. The self-vibrations are studied using a combination of the shooting technique and the parameter continuation method. Multipliers are calculated to analyze the stability of periodic vibrations and their bifurcations. The dynamic instability of the structure’s trivial equilibrium is studied by numerical simulation. For clamped-clamped and cantilever shells, the properties of their periodic, quasiperiodic, and chaotic motions are analyzed in detail.
{"title":"Self-vibrations of a truncated conical sandwich shell with a honeycomb core made by additive technologies","authors":"K. Avramov, B. Uspensky","doi":"10.15407/itm2022.02.087","DOIUrl":"https://doi.org/10.15407/itm2022.02.087","url":null,"abstract":"This paper presents a nonlinear mathematical model of self-vibrations of conical sandwich shells with a honeycomb core made by additive technologies. The vibrations of the structure are described by fifteen unknowns. Each layer of the structure is described by five unknowns: three projections of the displacements of the layer middle surface and two rotation angles of the middle surface normal. Displacement continuity conditions at the layer interfaces are used. The higher-order shear theory is used to describe the stress-strain state of the structure. The case of conical sandwich shell ? supersonic gas flow interaction is considered. Due to this interaction, self-vibrations of the shell structure are set up. In their analysis, the geometrical nonlinearity of the structure is accounted for. Motion equations of the structure are derived using the assumed-mode method, which uses the kinetic and the potential energy of the structure. The self-vibrations are represented as eigenmode expansions, which contain a set of generalized coordinates. A system of nonlinear autonomous ordinary differential equations in the generalized coordinates is derived. The self-vibrations are studied using a combination of the shooting technique and the parameter continuation method. Multipliers are calculated to analyze the stability of periodic vibrations and their bifurcations. The dynamic instability of the structure’s trivial equilibrium is studied by numerical simulation. For clamped-clamped and cantilever shells, the properties of their periodic, quasiperiodic, and chaotic motions are analyzed in detail.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122396749","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}
The purpose of this work is to determine the current trends in the development of low-orbit constellations of spacecraft with synthetic aperture radar (SAR), which have a number of significant advantages in Earth remote sensing. It is shown that the demand for Earth remote sensing data and products and services based thereon continues to grow worldwide. The applicability of SAR to Earth remote sensing is considered. The main differences and advantages of image acquisition using SAR spacecraft in comparison with optical spacecraft are shown. The main directions of using low-orbit SAR spacecraft in Earth remote sensing are identified. Land and water surface observation using SAR spacecraft is shown to be one of the most effective remote sensing methods. In particular, it is shown that low-orbit spacecraft constellations can be used to advantage in solving many tasks in the socio-economic sector and tasks aimed at continuous real-time monitoring of various objects. The characteristics of the various Earth remote sensing spacecraft constellations, in particular low-orbit commercial ones, launched into orbit during the past decade are considered. Problems in and prospects for the development of low-orbit SAR spacecraft constellations are elucidated. Existing and planned SAR spacecraft constellations with traditional and mini-satellite platform technologies are overviewed. It is shown that the performance characteristics continue to improve, thus allowing one to get data from any area of the Earth at any time. It is shown that small spacecraft in low and ultralow orbits have significant benefits over traditional spacecraft in power characteristics, but are outperformed by them in the duration of communication sessions and active life. The results obtained make it possible to work out recommendations on the designing of low-orbit constellations of domestic Earth remote sensing spacecraft, in particular on the development of orbit determination models and algorithms and spacecraft dynamics models.
{"title":"Present-day low-orbit constellations of Earth remote sensing spacecraft with synthetic aperture radar","authors":"O. Volosheniuk","doi":"10.15407/itm2022.02.059","DOIUrl":"https://doi.org/10.15407/itm2022.02.059","url":null,"abstract":"The purpose of this work is to determine the current trends in the development of low-orbit constellations of spacecraft with synthetic aperture radar (SAR), which have a number of significant advantages in Earth remote sensing. It is shown that the demand for Earth remote sensing data and products and services based thereon continues to grow worldwide. The applicability of SAR to Earth remote sensing is considered. The main differences and advantages of image acquisition using SAR spacecraft in comparison with optical spacecraft are shown. The main directions of using low-orbit SAR spacecraft in Earth remote sensing are identified. Land and water surface observation using SAR spacecraft is shown to be one of the most effective remote sensing methods. In particular, it is shown that low-orbit spacecraft constellations can be used to advantage in solving many tasks in the socio-economic sector and tasks aimed at continuous real-time monitoring of various objects. The characteristics of the various Earth remote sensing spacecraft constellations, in particular low-orbit commercial ones, launched into orbit during the past decade are considered. Problems in and prospects for the development of low-orbit SAR spacecraft constellations are elucidated. Existing and planned SAR spacecraft constellations with traditional and mini-satellite platform technologies are overviewed. It is shown that the performance characteristics continue to improve, thus allowing one to get data from any area of the Earth at any time. It is shown that small spacecraft in low and ultralow orbits have significant benefits over traditional spacecraft in power characteristics, but are outperformed by them in the duration of communication sessions and active life. The results obtained make it possible to work out recommendations on the designing of low-orbit constellations of domestic Earth remote sensing spacecraft, in particular on the development of orbit determination models and algorithms and spacecraft dynamics models.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122578815","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}
This paper discusses the use of the authors’ fast methods and programs for the calculation of 3D supersonic flow about a flying vehicle and thermogas dynamic processes in the components of an airframe-integrated ramjet. To conduct fast comprehensive calculations, use is made of marching methods, which are two to three orders of magnitude faster than pseudoviscosity methods. 3D supersonic flows about the airframe, in the inlet section of the air intake, and in the exhaust jet are calculated using a “viscous layer” model or Godunov’s scheme for the inviscid approximation. Subsonic flows in the outlet section of the air intake and in the combustion chamber are calculated using a “narrow channel” or a quasi-one-dimensional model. The elements of the presented methods and programs that complement a previously proposed fast comprehensive model are described in more detail. A method for assigning the spatial shape of the flying vehicle surface and the ramjet duct walls is described. A simplified approach to determining the critical area of the exit nozzle in the one-dimensional approximation is proposed. The paper substantiates the advantages of marching methods over pseudoviscosity ones in the predesigning of ramjets with direct account for flow choking, which may occur in the combustion chamber or the exit nozzle. The calculated 3D flows in the individual components and the full assembly of a stylized-shape flying vehicle are presented. The main advantages of the proposed methods and programs are their comprehensiveness and fast computation speed. Their use in the calculation of 3D supersonic flow about a ramjet flying vehicle shortens the ramjet component predesigning time.
{"title":"Methods and programs for comprehensive calculations of supersonic flow about ramjet flying vehicles","authors":"V. I. Timoshenko, V. P. Halynskyi","doi":"10.15407/itm2022.02.003","DOIUrl":"https://doi.org/10.15407/itm2022.02.003","url":null,"abstract":"This paper discusses the use of the authors’ fast methods and programs for the calculation of 3D supersonic flow about a flying vehicle and thermogas dynamic processes in the components of an airframe-integrated ramjet. To conduct fast comprehensive calculations, use is made of marching methods, which are two to three orders of magnitude faster than pseudoviscosity methods. 3D supersonic flows about the airframe, in the inlet section of the air intake, and in the exhaust jet are calculated using a “viscous layer” model or Godunov’s scheme for the inviscid approximation. Subsonic flows in the outlet section of the air intake and in the combustion chamber are calculated using a “narrow channel” or a quasi-one-dimensional model. The elements of the presented methods and programs that complement a previously proposed fast comprehensive model are described in more detail. A method for assigning the spatial shape of the flying vehicle surface and the ramjet duct walls is described. A simplified approach to determining the critical area of the exit nozzle in the one-dimensional approximation is proposed. The paper substantiates the advantages of marching methods over pseudoviscosity ones in the predesigning of ramjets with direct account for flow choking, which may occur in the combustion chamber or the exit nozzle. The calculated 3D flows in the individual components and the full assembly of a stylized-shape flying vehicle are presented. The main advantages of the proposed methods and programs are their comprehensiveness and fast computation speed. Their use in the calculation of 3D supersonic flow about a ramjet flying vehicle shortens the ramjet component predesigning time.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126202524","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}
The problem of increasing prediction accuracy for the motion of Earth-orbiting objects (EOOs) and detecting changes therein is topical for the tasks of spacecraft life prediction, space debris cataloguing, and navigation. Therefore, the problem of detecting changes in dynamic systems characterized by non-equidistant observations is topical. The purpose of this work is the development of autoregressive models with observations non-equidistant in time to detect changes in EOO motion. The methods employed are multivariate statistical analysis, time series prediction, and complex-system simulation under structural uncertainty. Data generated by NORAD (USA) were used as initial observations to describe EOO motion. They are actual, constantly updated, and freely available via the Internet. These data are presented in the Two-Line Element (TLE) format, which is a data format encoding a list of orbital elements of an EOO for a given point in time. This paper presents a method for constructing autoregressive models to describe the dynamics of EOOs represented by time series of TLE elements with values non-equidistant in time. On its basis, autoregressive models of the Sich-2 spacecraft’s dynamics were constructed. The standard errors of the models were analysed on examination samples, and significant deviations of the standard errors for the basic variables (apogee, perigee, eccentricity, longitude of ascending node, perigee argument, and average anomaly) were found, thus demonstrating changes in the Sich-2 motion from its basic regime. The novelty of this work lies in that the problem of detecting changes in EOO motion characteristics based on the proposed type of autoregressive models has not been considered before. Its practical value lies in that the simulation of the Sich-2 motion using time series of TLE elements allows one to detect changes in motion regimes; the method may be used in detecting in-service changes in EOO properties.
{"title":"Detection of changes in the motion of Earth-orbiting objects by autoregressive models in conditions of non-equidistant observations","authors":"O. Sarychev","doi":"10.15407/itm2022.02.025","DOIUrl":"https://doi.org/10.15407/itm2022.02.025","url":null,"abstract":"The problem of increasing prediction accuracy for the motion of Earth-orbiting objects (EOOs) and detecting changes therein is topical for the tasks of spacecraft life prediction, space debris cataloguing, and navigation. Therefore, the problem of detecting changes in dynamic systems characterized by non-equidistant observations is topical. The purpose of this work is the development of autoregressive models with observations non-equidistant in time to detect changes in EOO motion. The methods employed are multivariate statistical analysis, time series prediction, and complex-system simulation under structural uncertainty. Data generated by NORAD (USA) were used as initial observations to describe EOO motion. They are actual, constantly updated, and freely available via the Internet. These data are presented in the Two-Line Element (TLE) format, which is a data format encoding a list of orbital elements of an EOO for a given point in time. This paper presents a method for constructing autoregressive models to describe the dynamics of EOOs represented by time series of TLE elements with values non-equidistant in time. On its basis, autoregressive models of the Sich-2 spacecraft’s dynamics were constructed. The standard errors of the models were analysed on examination samples, and significant deviations of the standard errors for the basic variables (apogee, perigee, eccentricity, longitude of ascending node, perigee argument, and average anomaly) were found, thus demonstrating changes in the Sich-2 motion from its basic regime. The novelty of this work lies in that the problem of detecting changes in EOO motion characteristics based on the proposed type of autoregressive models has not been considered before. Its practical value lies in that the simulation of the Sich-2 motion using time series of TLE elements allows one to detect changes in motion regimes; the method may be used in detecting in-service changes in EOO properties.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131126070","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：