Recently considerable attention has been paid to the problem of estimating the pose of an on-orbit service object. Determining the pose at a close distance still remains an open line of research, especially for non-cooperative objects (targets) of on-orbit service. The goal of this work is to overview the state of the art in the problem of determining the relative motion parameters of on-orbit service objects with emphasis on close proximity operations with non-cooperative and unknown targets. The method employed is the analysis of publications devoted to this problem over the last decade. The analysis showed the following. Determining the pose of a non-cooperative orbital object using video systems is a classical approach due to the advantages of light weight and low power consumption. Video camera based pose estimation algorithms usually require prior knowledge of the target features. The main methods of pose estimation still involve approaches based on the recognition and correspondence of image features for consecutive frames or with a target model. Another major approach to pose determination is lidar navigation, where the recognition and correspondence of features based on lidar-derived target surface point clouds are also common methods. Recently, a trend has emerged towards the development of non-feature methods for target pose determination, including unknown targets. The three-dimensional nature of lidar point cloud data is favorable for target pose estimation without any target model. As to the applicability of target pose estimation methods to an unknown target, the implementation of the obvious approach based on constructing a three-dimensional model of the target by processing a series of its images prior to estimating its spatial motion takes a lot of time, which is critical in close proximity operations. The trend in target pose estimation is the development of methods for simultaneous estimation of the pose and shape of an unknown object. In general, the case of an unknown object has not yet been fully investigated.
{"title":"Analysis of the state of the art in the problem of determining the pose of on-orbit service objects","authors":"O. Fokov","doi":"10.15407/itm2023.01.054","DOIUrl":"https://doi.org/10.15407/itm2023.01.054","url":null,"abstract":"Recently considerable attention has been paid to the problem of estimating the pose of an on-orbit service object. Determining the pose at a close distance still remains an open line of research, especially for non-cooperative objects (targets) of on-orbit service. The goal of this work is to overview the state of the art in the problem of determining the relative motion parameters of on-orbit service objects with emphasis on close proximity operations with non-cooperative and unknown targets. The method employed is the analysis of publications devoted to this problem over the last decade. The analysis showed the following. Determining the pose of a non-cooperative orbital object using video systems is a classical approach due to the advantages of light weight and low power consumption. Video camera based pose estimation algorithms usually require prior knowledge of the target features. The main methods of pose estimation still involve approaches based on the recognition and correspondence of image features for consecutive frames or with a target model. Another major approach to pose determination is lidar navigation, where the recognition and correspondence of features based on lidar-derived target surface point clouds are also common methods. Recently, a trend has emerged towards the development of non-feature methods for target pose determination, including unknown targets. The three-dimensional nature of lidar point cloud data is favorable for target pose estimation without any target model. As to the applicability of target pose estimation methods to an unknown target, the implementation of the obvious approach based on constructing a three-dimensional model of the target by processing a series of its images prior to estimating its spatial motion takes a lot of time, which is critical in close proximity operations. The trend in target pose estimation is the development of methods for simultaneous estimation of the pose and shape of an unknown object. In general, the case of an unknown object has not yet been fully investigated.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123999592","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}
To solve the problem of satellite control and stabilization in emergencies, it is proposed to use a detonation rocket engine, which enables active maneuvering to avoid a collision with space debris. The goal of this work is to study a new way of rocket engine thrust vector control by acting with a detonation shock wave on the gas flow in the nozzle. A detonation wave in a supersonic flow in a nozzle was numerically simulated. The simulation was conducted in a non-stationary plane formulation at different angles of inclination of the detonation gas generator that initiates a detonation shock wave to the combustion chamber axis with the use of SolidWorks application software for the 11D25 engine of the Cyclone-3 third stage. The simulation results were used to pre-optimize the location of the detonation gas generator on the nozzle wall. It was found that the effect of the detonation wave on the main gas flow in the nozzle is caused by two force factors: the first is due to the reactive force produced by the detonation product injection into the nozzle and a high-pressure zone on the wall where the detonation gas generator is mounted, and the second is due to a change in pressure distribution over the nozzle surface. In order to increase the effect of the shock wave, the detonation products must be injected parallel to the main gas flow in the nozzle or at some angle. The simulation showed the drawbacks and advantages of detonation product injection at different angles. The detonation wave effect on a supersonic nozzle flow was studied experimentally. A system was developed to record the shock detonation wave propagation using a heat meter. A special nozzle model and a gas generator were developed to initiate a detonation wave interacting with a supersonic air flow. It was found out how the detonation wave separates the main flow from the nozzle walls in the overexpanded mode. The results may be used in the space-rocket industry to provide upper stage maneuvering to avoid a collision with space debris.
{"title":"Thrust vector control by detonation product injection into the supersonic nozzle area","authors":"S. Vasyliv, K. Ternova","doi":"10.15407/itm2023.01.068","DOIUrl":"https://doi.org/10.15407/itm2023.01.068","url":null,"abstract":"To solve the problem of satellite control and stabilization in emergencies, it is proposed to use a detonation rocket engine, which enables active maneuvering to avoid a collision with space debris. The goal of this work is to study a new way of rocket engine thrust vector control by acting with a detonation shock wave on the gas flow in the nozzle. A detonation wave in a supersonic flow in a nozzle was numerically simulated. The simulation was conducted in a non-stationary plane formulation at different angles of inclination of the detonation gas generator that initiates a detonation shock wave to the combustion chamber axis with the use of SolidWorks application software for the 11D25 engine of the Cyclone-3 third stage. The simulation results were used to pre-optimize the location of the detonation gas generator on the nozzle wall. It was found that the effect of the detonation wave on the main gas flow in the nozzle is caused by two force factors: the first is due to the reactive force produced by the detonation product injection into the nozzle and a high-pressure zone on the wall where the detonation gas generator is mounted, and the second is due to a change in pressure distribution over the nozzle surface. In order to increase the effect of the shock wave, the detonation products must be injected parallel to the main gas flow in the nozzle or at some angle. The simulation showed the drawbacks and advantages of detonation product injection at different angles. The detonation wave effect on a supersonic nozzle flow was studied experimentally. A system was developed to record the shock detonation wave propagation using a heat meter. A special nozzle model and a gas generator were developed to initiate a detonation wave interacting with a supersonic air flow. It was found out how the detonation wave separates the main flow from the nozzle walls in the overexpanded mode. The results may be used in the space-rocket industry to provide upper stage maneuvering to avoid a collision with space debris.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124742209","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. Pylypenko, O. Nikolayev, N. Khoriak, I. D. Bashliy, S. Dolgopolov
The most critical operating conditions of solid rocket motors (SRMs) are often due to the development of dynamic processes characterized by excess values of operating parameters. Pressure surges and a sharp increase in the combustion product temperature may impair the strength of the combustion chamber structure, cause its failure, and lead to critical conditions of the motor operation, up to extinguishing the propellant combustion in the motor. It is shown that both in steady and in unsteady operating conditions of an SRM, dynamic processes in its combustion chamber feature a complex interrelation of a large number of processes in the gas-dynamic space of the combustion chamber: physical, chemical, and thermodynamic (heat and mass exchange) processes. It is found that current studies of SRM operation instability are aimed at identifying mechanisms of combustion chamber pressure oscillations, which are usually due to combustion product vortex formation in the chamber space and acoustic feedback resulting from collisions of vortices with the SRM’s combustion chamber components or nozzle. Other lines of investigation are the analysis of SRM resonant damping and the establishment of a relationship between aluminum droplet combustion and SRM internal instability. It is noted that accelerations and vibrations of mixed-propellant combustion surfaces may greatly affect the combustion rate and the agglomeration, on-surface confinement, and burn-up of metal additives, which, in its turn, governs the combustion chamber acoustics. It is pointed out that the interaction of SRM combustion chamber pressure oscillations and the response of the SRM structure observed in flight tests of some rockets should be taken into account in predicting the stability of SRM dynamic processes. This interaction may call into question the sufficiency of SRM static tests and subsequent conclusions on the magnitude of its dynamic effect on the rocket structure.
{"title":"Dynamic processes in solid rocket motors and their interaction with rocket structure vibrations: the state of the art and current problems","authors":"O. Pylypenko, O. Nikolayev, N. Khoriak, I. D. Bashliy, S. Dolgopolov","doi":"10.15407/itm2023.01.003","DOIUrl":"https://doi.org/10.15407/itm2023.01.003","url":null,"abstract":"The most critical operating conditions of solid rocket motors (SRMs) are often due to the development of dynamic processes characterized by excess values of operating parameters. Pressure surges and a sharp increase in the combustion product temperature may impair the strength of the combustion chamber structure, cause its failure, and lead to critical conditions of the motor operation, up to extinguishing the propellant combustion in the motor. It is shown that both in steady and in unsteady operating conditions of an SRM, dynamic processes in its combustion chamber feature a complex interrelation of a large number of processes in the gas-dynamic space of the combustion chamber: physical, chemical, and thermodynamic (heat and mass exchange) processes. It is found that current studies of SRM operation instability are aimed at identifying mechanisms of combustion chamber pressure oscillations, which are usually due to combustion product vortex formation in the chamber space and acoustic feedback resulting from collisions of vortices with the SRM’s combustion chamber components or nozzle. Other lines of investigation are the analysis of SRM resonant damping and the establishment of a relationship between aluminum droplet combustion and SRM internal instability. It is noted that accelerations and vibrations of mixed-propellant combustion surfaces may greatly affect the combustion rate and the agglomeration, on-surface confinement, and burn-up of metal additives, which, in its turn, governs the combustion chamber acoustics. It is pointed out that the interaction of SRM combustion chamber pressure oscillations and the response of the SRM structure observed in flight tests of some rockets should be taken into account in predicting the stability of SRM dynamic processes. This interaction may call into question the sufficiency of SRM static tests and subsequent conclusions on the magnitude of its dynamic effect on the rocket structure.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123855706","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 goal of this work is to find the lower estimate of the no-failure probability (NFP) of a complex monotonic nonrecoverable system from the results of independent binomial tests of its components. Using the general-and-probabilistic method, the NFP is considered as a probability function polynomial, which is a linear homogeneous polynomial in each of the S variables where S is the number of system component types. Based on the method of confidence sets, the NFP lower estimate is found as the minimum of a function of an unknown multidimensional parameter at a probability of the aggregate test results (failure-free operation) of the system components equal to one minus the guaranteed confidence coefficient. The paper reports a system of equations, each of which for two component types relates the component reliability derivatives of the NFP (and one more equation relates the component reliability and the confidence coefficient). Conditions are found for the initial guess in a numerical solution of the above system of nonlinear equations (the number of the conditions is equal to the number of the component types minus one; each condition is a like sign for two functions each of which depends on the probability of the test results of a particular component type and the component reliability of this probability). In some specific cases, the program dimension can be reduced due to the simple structure of the probability function polynomial. The presented method gives a confidence reliability estimate with a guaranteed confidence coefficient for complex system that cannot be reduced to a serial-parallel or a parallel-serial structure and consist of components with an arbitrary type of failure time distribution. The method allows one to get an estimate at a small number of tests and a small number of failures or in their absence, which is of especial importance for high-reliability systems.
{"title":"Interval estimation of reliability indices from the results of complex system component tests","authors":"O.M. Savonik","doi":"10.15407/itm2023.01.105","DOIUrl":"https://doi.org/10.15407/itm2023.01.105","url":null,"abstract":"The goal of this work is to find the lower estimate of the no-failure probability (NFP) of a complex monotonic nonrecoverable system from the results of independent binomial tests of its components. Using the general-and-probabilistic method, the NFP is considered as a probability function polynomial, which is a linear homogeneous polynomial in each of the S variables where S is the number of system component types. Based on the method of confidence sets, the NFP lower estimate is found as the minimum of a function of an unknown multidimensional parameter at a probability of the aggregate test results (failure-free operation) of the system components equal to one minus the guaranteed confidence coefficient. The paper reports a system of equations, each of which for two component types relates the component reliability derivatives of the NFP (and one more equation relates the component reliability and the confidence coefficient). Conditions are found for the initial guess in a numerical solution of the above system of nonlinear equations (the number of the conditions is equal to the number of the component types minus one; each condition is a like sign for two functions each of which depends on the probability of the test results of a particular component type and the component reliability of this probability). In some specific cases, the program dimension can be reduced due to the simple structure of the probability function polynomial. The presented method gives a confidence reliability estimate with a guaranteed confidence coefficient for complex system that cannot be reduced to a serial-parallel or a parallel-serial structure and consist of components with an arbitrary type of failure time distribution. The method allows one to get an estimate at a small number of tests and a small number of failures or in their absence, which is of especial importance for high-reliability systems.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127850304","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 ensuring favorable climatic conditions in a particular territory is global for mankind. In the context of the global climate change, its resolution may be crucial for national economy management in many countries. By now, a number of engineering solutions have been proposed to develop means that may allow one to achieve the goal of global climate control. These solutions include an Earth orbit change concept, aerosol marine and stratospheric technologies, and a “sunshade” concept. One of the promising conceptual developments is a space-based “sunshade” technology. Taking into account the significant scientific background and a similar principle of operation of lighting (illuminative) systems, they were suggested to be used simultaneously with “sunshade” systems. The goal of this work is the development of a structure for a mathematical model of the ballistics and navigation of a space-based shading and lighting system (SBSLS). To do this, SBSLS structural modules were identified: a space-based industrial platform for SBSLS module production, passive and active shading and lighting modules, and service spacecraft. Generalized construction arrangements of the shading and lighting module were decided on. Based on the features of the SBSLS structural modules, a structure for a mathematical model of SBSLS ballistic and navigational support was developed. The structure comprises five components: an orbit estimator, an attitude motion estimator, an attitude and orbit control system, an optical estimator, and a geodetic estimator. A number of specific problems involving the choice of SBSLS design parameters at the conceptual design stage were identified and justified for further investigation. The combined use of the above modules may allow one to solve them.
{"title":"Features of the development of space-based shading and lighting systems for the Earth’s surface","authors":"A. Alpatov, E. Lapkhanov","doi":"10.15407/itm2023.01.025","DOIUrl":"https://doi.org/10.15407/itm2023.01.025","url":null,"abstract":"The problem of ensuring favorable climatic conditions in a particular territory is global for mankind. In the context of the global climate change, its resolution may be crucial for national economy management in many countries. By now, a number of engineering solutions have been proposed to develop means that may allow one to achieve the goal of global climate control. These solutions include an Earth orbit change concept, aerosol marine and stratospheric technologies, and a “sunshade” concept. One of the promising conceptual developments is a space-based “sunshade” technology. Taking into account the significant scientific background and a similar principle of operation of lighting (illuminative) systems, they were suggested to be used simultaneously with “sunshade” systems. The goal of this work is the development of a structure for a mathematical model of the ballistics and navigation of a space-based shading and lighting system (SBSLS). To do this, SBSLS structural modules were identified: a space-based industrial platform for SBSLS module production, passive and active shading and lighting modules, and service spacecraft. Generalized construction arrangements of the shading and lighting module were decided on. Based on the features of the SBSLS structural modules, a structure for a mathematical model of SBSLS ballistic and navigational support was developed. The structure comprises five components: an orbit estimator, an attitude motion estimator, an attitude and orbit control system, an optical estimator, and a geodetic estimator. A number of specific problems involving the choice of SBSLS design parameters at the conceptual design stage were identified and justified for further investigation. The combined use of the above modules may allow one to solve them.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115240016","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}
S. Bisyk, A. Sanin, V. Poshyvalov, O. Aristarkhov, M. V. Prykhodko, A.I. Kuzmytska, A.F. Lednianskyi
This paper considers the use of aluminum alloy parts for combined mine protection of armored combat vehicles. The study was concerned with anti-mine shields mounted on an armored combat vehicle body model. The model was made of 16 mm armor steel. The total mass of the model (without an anti-mine shield) was 31.1 kg. An anti-mine shield was gripped between two frames and secured with bolts. To eliminate the effect of the soil on the test results, the explosive charges were installed on a 70 mm metal plate. The charges were initiated with an ED-8Zh electrodetonator. TG-50/50 explosive was used. A DYTRAN 3200B acceleration sensor was mounted at the center of the model, and the sensor signal was measured using an experimental system. To assess the model acceleration without any energy loss by elastic or plastic deformations, the acceleration of the model with a rigid anti-mine shield (a rigid armor steel plate of thickness 10 mm and mass 10.7 kg) was assessed. A finite-element simulation of the model was conducted. The effect of explosion load parameters on the model acceleration was studied. The simulated and the actual deflections were compared using an EinScan Pro 2X Plus 3D scanner. The speed and the acceleration of the model with a rigid and a plastic anti-mine shield were simulated and measured. The results showed that annealed parts made of Al-Mg alloys, in particular AMg6 alloy, absorb the explosion energy better. Any of the anti-mine shields made of AMg6 alloy reduces the acceleration at the center of the plate and thus the load on the armored vehicle body by a factor of 20…25 in comparison with the anti-mine shields made of armor steel. It was shown that annealing best provides the required physical and mechanical characteristics of the load-bearing parts of anti-mine shields, it is advisable to shape and structurize their porous energy-absorbing elements by pressing up to 33 MPa, it is most advisable to paste the porous energy-absorbing elements to the load-bearing parts, and after separate tests of load-bearing part and porous energy-absorbing element material specimens it is advisable to try out combined constructions of anti-mine shields for armored combat vehicles of different purposes.
本文研究了铝合金零件在装甲战车组合防雷中的应用。该研究涉及安装在装甲战斗车辆车身模型上的反地雷盾牌。该模型由16毫米装甲钢制成。模型的总质量(不含反地雷盾)为31.1千克。一个防地雷盾牌夹在两个框架之间，用螺栓固定住。为了消除土壤对试验结果的影响，将炸药装在70毫米的金属板上。炸药是用ED-8Zh型电雷管引爆的。采用TG-50/50炸药。在模型中央安装DYTRAN 3200B加速度传感器，利用实验系统对传感器信号进行测量。为了评估模型在弹塑性变形不造成能量损失的情况下的加速度，我们对带有刚性防雷盾(厚度为10 mm，质量为10.7 kg的刚性装甲钢板)的模型进行了加速度评估。对该模型进行了有限元仿真。研究了爆炸载荷参数对模型加速度的影响。使用EinScan Pro 2X Plus 3D扫描仪对模拟和实际挠度进行比较。对该模型的速度和加速度分别进行了仿真和测量。结果表明，Al-Mg合金特别是AMg6合金退火后的零件吸收爆炸能效果较好。任何一种由AMg6合金制成的防雷盾，与由装甲钢制成的防雷盾相比，都能减少板中心的加速度，从而减少装甲车辆车身上的负荷，减少了20…25倍。结果表明，退火处理能较好地提供抗地雷屏蔽体承重件所需的物理力学特性，多孔吸能元件的成型和结构宜采用加压至33 MPa的方法，多孔吸能元件最宜粘贴在承重件上。在分别对承重部分和多孔吸能单元材料试样进行试验后，建议对不同用途的装甲战斗车辆进行防雷盾组合结构的试验。
{"title":"Combined shock and mine protection based on aluminum alloy parts","authors":"S. Bisyk, A. Sanin, V. Poshyvalov, O. Aristarkhov, M. V. Prykhodko, A.I. Kuzmytska, A.F. Lednianskyi","doi":"10.15407/itm2023.01.076","DOIUrl":"https://doi.org/10.15407/itm2023.01.076","url":null,"abstract":"This paper considers the use of aluminum alloy parts for combined mine protection of armored combat vehicles. The study was concerned with anti-mine shields mounted on an armored combat vehicle body model. The model was made of 16 mm armor steel. The total mass of the model (without an anti-mine shield) was 31.1 kg. An anti-mine shield was gripped between two frames and secured with bolts. To eliminate the effect of the soil on the test results, the explosive charges were installed on a 70 mm metal plate. The charges were initiated with an ED-8Zh electrodetonator. TG-50/50 explosive was used. A DYTRAN 3200B acceleration sensor was mounted at the center of the model, and the sensor signal was measured using an experimental system. To assess the model acceleration without any energy loss by elastic or plastic deformations, the acceleration of the model with a rigid anti-mine shield (a rigid armor steel plate of thickness 10 mm and mass 10.7 kg) was assessed. A finite-element simulation of the model was conducted. The effect of explosion load parameters on the model acceleration was studied. The simulated and the actual deflections were compared using an EinScan Pro 2X Plus 3D scanner. The speed and the acceleration of the model with a rigid and a plastic anti-mine shield were simulated and measured. The results showed that annealed parts made of Al-Mg alloys, in particular AMg6 alloy, absorb the explosion energy better. Any of the anti-mine shields made of AMg6 alloy reduces the acceleration at the center of the plate and thus the load on the armored vehicle body by a factor of 20…25 in comparison with the anti-mine shields made of armor steel. It was shown that annealing best provides the required physical and mechanical characteristics of the load-bearing parts of anti-mine shields, it is advisable to shape and structurize their porous energy-absorbing elements by pressing up to 33 MPa, it is most advisable to paste the porous energy-absorbing elements to the load-bearing parts, and after separate tests of load-bearing part and porous energy-absorbing element material specimens it is advisable to try out combined constructions of anti-mine shields for armored combat vehicles of different purposes.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122499119","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}
Low near-circular orbits of Earth remote sensing (ERS) satellites are considered. The objective is to select the orbits most suitable for a particular satellite mission. In particular, the problem of an approximate determination of the orbit parameters that allow a satisfactory satellite survey of the target surface of the Earth is considered. The main desires of observation system developers regarding the conditions of the Earth's surface survey are considered. To reconcile these desires with the regularities of satellite motion in low Earth orbits, use may be made of simple models that describe these regularities. In doing so, it is desirable to visualize viewing swaths on the Earth's surface. A compromise between the desires of observation system developers and the satellite motion regularities is the selection of orbits that best meet the characteristics of a particular satellite and its observation system. This article presents a simple model and algorithm that make it possible to preselect ERS satellite orbits. The proposed model is based on familiar relationships, and the novelty of the article lies in a compact and generalized presentation of the model for ERS satellite orbit preselection. The article presents models that make it possible to estimate the satellite swath width and choose the orbit inclination angle, a stable orbit shape, the orbit altitude, and the orbital period. The advantages and disadvantages of solar synchronous orbits are considered. Analytical expressions are constructed to fairly simply estimate the excursion of a satellite from its operational orbit under the action of the aerodynamic drag, estimate the rate of recovery of the orbit parameters under the action of a constant transversal control acceleration, and determine allowable time intervals between engine starts and engine operation intervals. The advantages of repeat ground track orbits are shown. The simplest model for calculating and visualizing satellite viewing swathes of the Earth's surface is constructed. Thus, the article proposes a simple algorithm for the preselection of low Earth orbits for ERS satellites with a satisfactory observation of the target surface of the Earth.
{"title":"Preselection of the reference orbit for an Earth remote sensing satellite","authors":"A. Alpatov, A. Maslova, A. Pirozhenko","doi":"10.15407/itm2023.01.014","DOIUrl":"https://doi.org/10.15407/itm2023.01.014","url":null,"abstract":"Low near-circular orbits of Earth remote sensing (ERS) satellites are considered. The objective is to select the orbits most suitable for a particular satellite mission. In particular, the problem of an approximate determination of the orbit parameters that allow a satisfactory satellite survey of the target surface of the Earth is considered. The main desires of observation system developers regarding the conditions of the Earth's surface survey are considered. To reconcile these desires with the regularities of satellite motion in low Earth orbits, use may be made of simple models that describe these regularities. In doing so, it is desirable to visualize viewing swaths on the Earth's surface. A compromise between the desires of observation system developers and the satellite motion regularities is the selection of orbits that best meet the characteristics of a particular satellite and its observation system. This article presents a simple model and algorithm that make it possible to preselect ERS satellite orbits. The proposed model is based on familiar relationships, and the novelty of the article lies in a compact and generalized presentation of the model for ERS satellite orbit preselection. The article presents models that make it possible to estimate the satellite swath width and choose the orbit inclination angle, a stable orbit shape, the orbit altitude, and the orbital period. The advantages and disadvantages of solar synchronous orbits are considered. Analytical expressions are constructed to fairly simply estimate the excursion of a satellite from its operational orbit under the action of the aerodynamic drag, estimate the rate of recovery of the orbit parameters under the action of a constant transversal control acceleration, and determine allowable time intervals between engine starts and engine operation intervals. The advantages of repeat ground track orbits are shown. The simplest model for calculating and visualizing satellite viewing swathes of the Earth's surface is constructed. Thus, the article proposes a simple algorithm for the preselection of low Earth orbits for ERS satellites with a satisfactory observation of the target surface of the Earth.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116121431","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. Markova, M. Sobolevska, H. Kovtun, V. Maliy, D. Horobets
The importance of this work for Ukraine stems from the need for efficient freight transportation technologies, freight car fleet renewal, introducing swap-body freight cars, and increasing their operating safety. Swap-body cars are an innovation in freight services. Traditionally, versatile and specialized freight cars consist of an undercarriage part (running gear, automatic couples, and automatic braking devices), which, as a rule, is versatile, and a body part (an underframe and a body). The cost of the former and the latter is 80 and 20 per cent, respectively, of the total car cost. The idea of a swap-body car is to separate the underframe from the car body and include the former into the undercarriage part, thus leaving only the car body in the body part. Thus, the undercarriage part of a car of this type is a flat car for swap bodies, which consists of an underframe, running gear, automatic couples, automatic braking devices, and body fasteners. A new type of freight rail vehicles for unimodal railway transportation is the swap-body car, whose bodies can be replaced according to seasonal freights. For the Ukrainian railways, it is expedient to develop a swap-body car design of their own. This calls for scientific and technical support at the design and the operational development stage. The aim of this work is to determine the maximum loads on the load-bearing structural elements of swap-body cars in normal operation and to work out recommendations on a prospective home design of a swap-body freight car. This paper presents a mathematical model of 3D vibrations of a swap-body freight car in its normal motion along a track of arbitrary alignment, which accounts for the technical condition of the car undercarriage and the track. This model underlies the scientific and technical novelty of the paper. The analytical model of a swap-body car moving along a track is a mechanical system of rigid bodies. For each wheel, the track is simulated as an equivalent mass, which can move only in a vertical and a lateral horizontal direction and bears in these directions on springs and viscous dampers, which model the elastoviscous properties of the rails and the underrail base. The nonlinear differential equations of the system’s dynamics are solved by the Adams?Bashforth method. The paper presents a numerical estimate of the dynamics of motion of cars with swap bodies of different length and mass. For all the car motion variants considered, the maximum forces in the fitting supports whereby the body is supported on the undercarriage do not exceed their permissible values. The calculated values of the flat car’s dynamic parameters show that in terms of safety a car speed higher than 80 km/h is not safe for all the body-on-undercarriage layouts considered. Practically important recommendations on a prospective home design of a swap-body freight car are presented. The innovative technology of freight transportation with the use of swap-body cars will allow o
{"title":"Proposals on a prospective home design for a swap-body freight car","authors":"O. Markova, M. Sobolevska, H. Kovtun, V. Maliy, D. Horobets","doi":"10.15407/itm2023.01.090","DOIUrl":"https://doi.org/10.15407/itm2023.01.090","url":null,"abstract":"The importance of this work for Ukraine stems from the need for efficient freight transportation technologies, freight car fleet renewal, introducing swap-body freight cars, and increasing their operating safety. Swap-body cars are an innovation in freight services. Traditionally, versatile and specialized freight cars consist of an undercarriage part (running gear, automatic couples, and automatic braking devices), which, as a rule, is versatile, and a body part (an underframe and a body). The cost of the former and the latter is 80 and 20 per cent, respectively, of the total car cost. The idea of a swap-body car is to separate the underframe from the car body and include the former into the undercarriage part, thus leaving only the car body in the body part. Thus, the undercarriage part of a car of this type is a flat car for swap bodies, which consists of an underframe, running gear, automatic couples, automatic braking devices, and body fasteners. A new type of freight rail vehicles for unimodal railway transportation is the swap-body car, whose bodies can be replaced according to seasonal freights. For the Ukrainian railways, it is expedient to develop a swap-body car design of their own. This calls for scientific and technical support at the design and the operational development stage. The aim of this work is to determine the maximum loads on the load-bearing structural elements of swap-body cars in normal operation and to work out recommendations on a prospective home design of a swap-body freight car. This paper presents a mathematical model of 3D vibrations of a swap-body freight car in its normal motion along a track of arbitrary alignment, which accounts for the technical condition of the car undercarriage and the track. This model underlies the scientific and technical novelty of the paper. The analytical model of a swap-body car moving along a track is a mechanical system of rigid bodies. For each wheel, the track is simulated as an equivalent mass, which can move only in a vertical and a lateral horizontal direction and bears in these directions on springs and viscous dampers, which model the elastoviscous properties of the rails and the underrail base. The nonlinear differential equations of the system’s dynamics are solved by the Adams?Bashforth method. The paper presents a numerical estimate of the dynamics of motion of cars with swap bodies of different length and mass. For all the car motion variants considered, the maximum forces in the fitting supports whereby the body is supported on the undercarriage do not exceed their permissible values. The calculated values of the flat car’s dynamic parameters show that in terms of safety a car speed higher than 80 km/h is not safe for all the body-on-undercarriage layouts considered. Practically important recommendations on a prospective home design of a swap-body freight car are presented. The innovative technology of freight transportation with the use of swap-body cars will allow o","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"350 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131459297","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}
Nowadays, for solving new problems, rocket engine nozzle developers are increasingly turning to non- traditional nozzle configurations that differ from the classic Laval one. A relatively new line in the design of supersonic nozzles is the development of the so-called bell-shaped nozzle, which, unlike the classical Laval nozzle, has a larger angle of entry into the supersonic part of the nozzle. In this case, dual bell nozzles, which have two flow expansion sections in their supersonic part, are considered. However, the effect of the length ratio of the two flow expansion sections of a truncated nozzle on its characteristics has not yet been studied. The goal of this work is to determine the effect of the length of the upstream conical supersonic section on the static pressure distribution in the nozzle and its thrust characteristics with the shape of the bell-shaped tip kept unchanged. The nozzle characteristics were studied using the ANSYS Fluent computing package. It was shown that the flow patterns in the nozzle (velocity fields) change with the length of the conical part upstream of the tip and the underexpansion degree. Under terrestrial conditions (Pн = 1 bar), all variants show a developed separation zone that starts from the corner point where the tip is connected to the conical part. In this case, the pressure on the nozzle wall is nearly equal to the ambient pressure. At a large flow underexpansion degree (P0 = 300 bar) and in low-pressure conditions conditions (Pн =0.1 bar), the flow in the tip is adjacent to the wall. At a large flow underexpansion degree, the pressure in the nozzle increases from the corner point to the tip exit, and the pressure at the tip exit increases with decreasing tip length. The nozzle thrust coefficient decreases with increasing flow underexpansion degree, and it reaches a constant value after the flow becomes adjacent to the tip wall downstream of the corner point where the tip is connected to the nozzle. At high flow underexpansion degrees, the nozzle thrust coefficient is higher for a nozzle with a longer conical part. The calculated results are in good agreement with experimental data on nozzles of this type.
{"title":"Effect of the length of truncated nozzle with a tip on its thrust characteristics","authors":"K. Ternova","doi":"10.15407/itm2022.04.026","DOIUrl":"https://doi.org/10.15407/itm2022.04.026","url":null,"abstract":"Nowadays, for solving new problems, rocket engine nozzle developers are increasingly turning to non- traditional nozzle configurations that differ from the classic Laval one. A relatively new line in the design of supersonic nozzles is the development of the so-called bell-shaped nozzle, which, unlike the classical Laval nozzle, has a larger angle of entry into the supersonic part of the nozzle. In this case, dual bell nozzles, which have two flow expansion sections in their supersonic part, are considered. However, the effect of the length ratio of the two flow expansion sections of a truncated nozzle on its characteristics has not yet been studied. The goal of this work is to determine the effect of the length of the upstream conical supersonic section on the static pressure distribution in the nozzle and its thrust characteristics with the shape of the bell-shaped tip kept unchanged. The nozzle characteristics were studied using the ANSYS Fluent computing package. It was shown that the flow patterns in the nozzle (velocity fields) change with the length of the conical part upstream of the tip and the underexpansion degree. Under terrestrial conditions (Pн = 1 bar), all variants show a developed separation zone that starts from the corner point where the tip is connected to the conical part. In this case, the pressure on the nozzle wall is nearly equal to the ambient pressure. At a large flow underexpansion degree (P0 = 300 bar) and in low-pressure conditions conditions (Pн =0.1 bar), the flow in the tip is adjacent to the wall. At a large flow underexpansion degree, the pressure in the nozzle increases from the corner point to the tip exit, and the pressure at the tip exit increases with decreasing tip length. The nozzle thrust coefficient decreases with increasing flow underexpansion degree, and it reaches a constant value after the flow becomes adjacent to the tip wall downstream of the corner point where the tip is connected to the nozzle. At high flow underexpansion degrees, the nozzle thrust coefficient is higher for a nozzle with a longer conical part. The calculated results are in good agreement with experimental data on nozzles of this type.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134447459","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}
ology, in particular, space-rocket engineering, oil-and-gas engineering, power engineering, construction, etc. The presence of openings in their plate and shell components leads to a sharp increase in local stresses, which, under certain conditions, may trigger destructive processes. The use of functionally graded materials (FGMs) with certain mechanical properties can significantly reduce the stress concentration in the vicinity of local concentrators in the form of openings, cutouts, fillets, grooves, etc. This paper presents the results of computer simulation and finite element analysis of the stress and strain fields of thin plates and thin-walled cylindrical shells with a circular opening and an annular FGM inclusion surrounding it. The effect of the dimensions of the FGM inclusion and the law of variation of its elastic modulus on the stress and strain concentration in the vicinity of the opening was studied. The stress and strain intensity distribution in local stress concentration zones was obtained. It was found that an annular FGM inclusion with certain mechanical properties can reduce the stress concentration factor by more than 30%. In this case, a proportional decrease in strain intensity in the vicinity of the opening is also observed. The law of variation of the elastic modulus of the FGM inclusion and the inclusion width have a significant effect not only on the level of stress and strain concentration, but also on the stress and strain pattern. The results of the large-scale computational experiments show that an FGM annular inclusion reduces both the stress and the strain intensity around the opening. Therefore, the use of annular FGM reinforcements in plates and cylindrical shells with openings makes it possible to control the distribution and magnitude of the stress and strain intensities in local stress and strain concentration zones.
{"title":"Effect of a functionally graded material inclusion on the stress concentration in thin plates and cylindrical shells with a circular opening","authors":"E. Hart, V. Hudramovich, V.I. Terokhin","doi":"10.15407/itm2022.04.067","DOIUrl":"https://doi.org/10.15407/itm2022.04.067","url":null,"abstract":"ology, in particular, space-rocket engineering, oil-and-gas engineering, power engineering, construction, etc. The presence of openings in their plate and shell components leads to a sharp increase in local stresses, which, under certain conditions, may trigger destructive processes. The use of functionally graded materials (FGMs) with certain mechanical properties can significantly reduce the stress concentration in the vicinity of local concentrators in the form of openings, cutouts, fillets, grooves, etc. This paper presents the results of computer simulation and finite element analysis of the stress and strain fields of thin plates and thin-walled cylindrical shells with a circular opening and an annular FGM inclusion surrounding it. The effect of the dimensions of the FGM inclusion and the law of variation of its elastic modulus on the stress and strain concentration in the vicinity of the opening was studied. The stress and strain intensity distribution in local stress concentration zones was obtained. It was found that an annular FGM inclusion with certain mechanical properties can reduce the stress concentration factor by more than 30%. In this case, a proportional decrease in strain intensity in the vicinity of the opening is also observed. The law of variation of the elastic modulus of the FGM inclusion and the inclusion width have a significant effect not only on the level of stress and strain concentration, but also on the stress and strain pattern. The results of the large-scale computational experiments show that an FGM annular inclusion reduces both the stress and the strain intensity around the opening. Therefore, the use of annular FGM reinforcements in plates and cylindrical shells with openings makes it possible to control the distribution and magnitude of the stress and strain intensities in local stress and strain concentration zones.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"441 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116405386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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