Passive damping augmentation is one of attractive methods for vibration suppression to various kinds of structures because it is definitely stable and generally simple. Using viscous adhesive indicated a remarkable effect to the vibration suppression in the practical application to a satellite. In this paper, mathematical model of thin viscous adhesive layer using non-linear elements has been proposed. In this model, the characteristics of elements are correlated with non-linear internal phenomena of polymer. The simulation results using this proposal model are good agreement with experimental ones.
{"title":"Proposal of Vibration Suppression Model Using Thin Film with Viscous Lamina","authors":"H. Okubo, N. Watanabe, K. Minesugi, J. Onoda","doi":"10.2322/JJSASS.59.55","DOIUrl":"https://doi.org/10.2322/JJSASS.59.55","url":null,"abstract":"Passive damping augmentation is one of attractive methods for vibration suppression to various kinds of structures because it is definitely stable and generally simple. Using viscous adhesive indicated a remarkable effect to the vibration suppression in the practical application to a satellite. In this paper, mathematical model of thin viscous adhesive layer using non-linear elements has been proposed. In this model, the characteristics of elements are correlated with non-linear internal phenomena of polymer. The simulation results using this proposal model are good agreement with experimental ones.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122423457","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 study shows two fundamental aspects related to fracture characterization of sandwich beams for aerospace application; 1) formulation of energy release rates associated with face sheet debonding or core cracking in sandwich beams with residual thermal stresses, and 2) crack kinking analysis of foam core sandwich beams. Energy release rates are formulated using the bi-layer shear deformable beam model with consideration of residual thermal stresses. This formulation is specifically applied to double cantilever beam (DCB), end notched flexure (ENF) and mixed mode bending (MMB) tests of sandwich structures. The derived analytical results are verified by comparison with finite element analysis. Next, the present formulation is applied to the prediction of crack kinking behaviors in foam core sandwich beams. It is demonstrated that overall crack kinking behaviors in foam core sandwich beams are well predicted using the present method. Some discussions on the fracture toughness measurement considering residual thermal stresses are also provided.
{"title":"Analytical Study on the Fracture Toughness Characterization Tests of Foam Core Sandwich Specimens","authors":"T. Yokozeki","doi":"10.2322/JJSASS.59.16","DOIUrl":"https://doi.org/10.2322/JJSASS.59.16","url":null,"abstract":"This study shows two fundamental aspects related to fracture characterization of sandwich beams for aerospace application; 1) formulation of energy release rates associated with face sheet debonding or core cracking in sandwich beams with residual thermal stresses, and 2) crack kinking analysis of foam core sandwich beams. Energy release rates are formulated using the bi-layer shear deformable beam model with consideration of residual thermal stresses. This formulation is specifically applied to double cantilever beam (DCB), end notched flexure (ENF) and mixed mode bending (MMB) tests of sandwich structures. The derived analytical results are verified by comparison with finite element analysis. Next, the present formulation is applied to the prediction of crack kinking behaviors in foam core sandwich beams. It is demonstrated that overall crack kinking behaviors in foam core sandwich beams are well predicted using the present method. Some discussions on the fracture toughness measurement considering residual thermal stresses are also provided.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122288900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"輻射加熱を考慮したMHD Heat Shieldの数値シミュレーション","authors":"智之 吉野, 貴康 藤野, 本雄 石川","doi":"10.2322/JJSASS.58.349","DOIUrl":"https://doi.org/10.2322/JJSASS.58.349","url":null,"abstract":"","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115777204","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 paper is to introduce a velocity and distance control system for leader-following UAVs. In our previous paper, we already proposed a velocity and distance control system, but the system has a problem of ``offsets'' due to aerodynamic errors and/or leader trajectories. So in this paper, in order to eliminate the offset, a new approach of the velocity and distance control design is introduced. Simulation results show that the proposed velocity and distance control system provides a good performance and there are no offsets.
{"title":"A Velocity and Distance Control System Synthesis Using Dynamic Inversion with PI Control","authors":"K. Enomoto, T. Yamasaki, H. Takano, Y. Baba","doi":"10.2322/JJSASS.58.285","DOIUrl":"https://doi.org/10.2322/JJSASS.58.285","url":null,"abstract":"The purpose of this paper is to introduce a velocity and distance control system for leader-following UAVs. In our previous paper, we already proposed a velocity and distance control system, but the system has a problem of ``offsets'' due to aerodynamic errors and/or leader trajectories. So in this paper, in order to eliminate the offset, a new approach of the velocity and distance control design is introduced. Simulation results show that the proposed velocity and distance control system provides a good performance and there are no offsets.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128525232","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}
A. Umemura, Sho Kawanabe, Hiroshi Kojika, Feng Chen, J. Shinjo
To validate our proposed atomization theory, a series of microgravity experiments were conducted for a water jet issued into an otherwise quiescent atmosphere. The present paper reports findings from the case of liquid Weber number being nearly equal to unity. The water contained in a syringe is pushed by a piston which moves at a constant speed. The initial overshoot of liquid issue speed produces a long water column, whose length is reduced at every instant of subsequent disintegration interacting with the nozzle exit. The balance between tip contraction speed and liquid issue speed, which is attained by the selection of the Weber number, enables us to observe the disintegration process in detail. It is revealed that the short-wave breakup mechanism is characterized as the local destabilization which takes place at the short neck part bridging the tip bulb and the upstream high pressure crest part and that the neck maintains the nature of propagative capillary wave until a final stage of disintegration.
{"title":"Findings from Microgravity Experiments on Low-Speed Water Jet Disintegration","authors":"A. Umemura, Sho Kawanabe, Hiroshi Kojika, Feng Chen, J. Shinjo","doi":"10.2322/JJSASS.58.245","DOIUrl":"https://doi.org/10.2322/JJSASS.58.245","url":null,"abstract":"To validate our proposed atomization theory, a series of microgravity experiments were conducted for a water jet issued into an otherwise quiescent atmosphere. The present paper reports findings from the case of liquid Weber number being nearly equal to unity. The water contained in a syringe is pushed by a piston which moves at a constant speed. The initial overshoot of liquid issue speed produces a long water column, whose length is reduced at every instant of subsequent disintegration interacting with the nozzle exit. The balance between tip contraction speed and liquid issue speed, which is attained by the selection of the Weber number, enables us to observe the disintegration process in detail. It is revealed that the short-wave breakup mechanism is characterized as the local destabilization which takes place at the short neck part bridging the tip bulb and the upstream high pressure crest part and that the neck maintains the nature of propagative capillary wave until a final stage of disintegration.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126257748","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}
Abstract A coupled thermal–electrical analysis of carbon fiber reinforced polymer composites (CFRP) exposed to simulated lightning current was conducted in order to elucidate the damage behavior caused by a lightning strike with the numerical results being compared to experimental results. Based on the experimental results and a preliminary analysis, the specific mechanism of electrical conduction through the thickness direction of CFRP following thermal decomposition was revealed to be a key parameter for accurate numerical simulation. In particular, assuming the electrical conductivity in the thickness direction to be linear with respect to temperature in the range from the epoxy decomposition temperature to carbon sublimation temperature produced reasonable numerical results. The delamination area and damage depth were estimated from numerical results and thermal decomposition behavior of CFRP with the estimated damage area agreeing qualitatively with the experimental results. Numerical results suggest that Joule heat generation significantly influences lightning strike damage.
{"title":"Coupled Thermal-Electrical Analysis for Carbon Fiber Composites Exposed to Simulated Lightning Current","authors":"T. Ogasawara, Y. Hirano, A. Yoshimura","doi":"10.2322/JJSASS.57.336","DOIUrl":"https://doi.org/10.2322/JJSASS.57.336","url":null,"abstract":"Abstract A coupled thermal–electrical analysis of carbon fiber reinforced polymer composites (CFRP) exposed to simulated lightning current was conducted in order to elucidate the damage behavior caused by a lightning strike with the numerical results being compared to experimental results. Based on the experimental results and a preliminary analysis, the specific mechanism of electrical conduction through the thickness direction of CFRP following thermal decomposition was revealed to be a key parameter for accurate numerical simulation. In particular, assuming the electrical conductivity in the thickness direction to be linear with respect to temperature in the range from the epoxy decomposition temperature to carbon sublimation temperature produced reasonable numerical results. The delamination area and damage depth were estimated from numerical results and thermal decomposition behavior of CFRP with the estimated damage area agreeing qualitatively with the experimental results. Numerical results suggest that Joule heat generation significantly influences lightning strike damage.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130184135","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}
K. Higashino, M. Sugioka, Takao Kobayashi, Ryojiro Minato, Shunsuke Ooya, Yousuke Sasayama
Liquefied Natural Gas (LNG) is lower cost, higher density and easier handling than Liquefied hydrogen (LH2), therefore, is expected as the most promising candidate for the next generation rocket propellant. For LNG propellant, a full expander or an expander cycle rocket engine with regenerative cooling system is expected because its molecular weight is middle value between LH2 and Kerosene. Temperature of turbopump driven LNG gas should be higher to improve the specific impulse or combustion pressure for these rocket engine. In this case, coking of LNG in heat exchanger or regenerative cooling system becomes a significant problem. In the present study, two coking inhibition methods, n-C6H14 coating and graphite coating, are presented and their effects are evaluated. Contrary to our expectation, the former method is accelerated the LNG pyrolysis, resulting of coking promotion. On the other hand graphite coating can successfully inhibit coking up to 973 K.
{"title":"Fundamental Study on Coking Inhibition for Regenerative Cooled LNG Rocket Engines","authors":"K. Higashino, M. Sugioka, Takao Kobayashi, Ryojiro Minato, Shunsuke Ooya, Yousuke Sasayama","doi":"10.2322/JJSASS.58.138","DOIUrl":"https://doi.org/10.2322/JJSASS.58.138","url":null,"abstract":"Liquefied Natural Gas (LNG) is lower cost, higher density and easier handling than Liquefied hydrogen (LH2), therefore, is expected as the most promising candidate for the next generation rocket propellant. For LNG propellant, a full expander or an expander cycle rocket engine with regenerative cooling system is expected because its molecular weight is middle value between LH2 and Kerosene. Temperature of turbopump driven LNG gas should be higher to improve the specific impulse or combustion pressure for these rocket engine. In this case, coking of LNG in heat exchanger or regenerative cooling system becomes a significant problem. In the present study, two coking inhibition methods, n-C6H14 coating and graphite coating, are presented and their effects are evaluated. Contrary to our expectation, the former method is accelerated the LNG pyrolysis, resulting of coking promotion. On the other hand graphite coating can successfully inhibit coking up to 973 K.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126408973","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}
K. Higashino, S. Komazaki, Yousuke Sasayama, K. Kimoto, H. Sakaguchi, T. Ishibashi
For the regenerative cooling cycle LNG rocket engines, improvement Nickel Electroforming technology and analysis are the major problem because of high reliability and low cost at the design and fabrication. This paper describes analysis methods, results and the successful Improved Nickel Electroforming of the stress and strain level at the Electron beam heat zone.
{"title":"Fundamental Study of Improved Nickel Electroforming for the Regenerative Rocket Chamber","authors":"K. Higashino, S. Komazaki, Yousuke Sasayama, K. Kimoto, H. Sakaguchi, T. Ishibashi","doi":"10.2322/JJSASS.58.146","DOIUrl":"https://doi.org/10.2322/JJSASS.58.146","url":null,"abstract":"For the regenerative cooling cycle LNG rocket engines, improvement Nickel Electroforming technology and analysis are the major problem because of high reliability and low cost at the design and fabrication. This paper describes analysis methods, results and the successful Improved Nickel Electroforming of the stress and strain level at the Electron beam heat zone.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127958335","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}
Numerical simulation on the Air Data Sensor System (ADS), which measures the flow angles and Mach number using the surface pressures on a nose cone, was conducted in this study. The effect of the half cone angle on the flow angle and Mach number measurement was investigated. As a result, we found that a large half cone angle achieves a high sensitivity at the flow angle measurement. It was also found that a small half cone angle achieves a high sensitivity at the Mach number measurement. To satisfy these conflicting requests, we proposed a new shape nose cone which has two different gradients. The high sensitivity was achieved at both the flow angle measurement and Mach number measurement by this new shape nose cone.
{"title":"Numerical Study on Flow Angles and Mach Number Measurement Using the Surface Pressure of a Supersonic Aircraft with Nosecone","authors":"Katsuyoshi Fukiba, N. Tsuboi, Hiroaki Kobayashi","doi":"10.2322/JJSASS.58.130","DOIUrl":"https://doi.org/10.2322/JJSASS.58.130","url":null,"abstract":"Numerical simulation on the Air Data Sensor System (ADS), which measures the flow angles and Mach number using the surface pressures on a nose cone, was conducted in this study. The effect of the half cone angle on the flow angle and Mach number measurement was investigated. As a result, we found that a large half cone angle achieves a high sensitivity at the flow angle measurement. It was also found that a small half cone angle achieves a high sensitivity at the Mach number measurement. To satisfy these conflicting requests, we proposed a new shape nose cone which has two different gradients. The high sensitivity was achieved at both the flow angle measurement and Mach number measurement by this new shape nose cone.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125350390","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}
Subsonic jets at Mach number Mj = 0.9 are computed using compressible Large Eddy Simulation and Kirchhoff method in order to investigate the effects of the inflow forcing on the flow and sound field. Four parameters are varied in the jet inflow: the use of the first modes in the ring vortex excitation involving several azimuthal modes, the forcing amplitude, the thickness of disturbances, and the existence of the inflow forcing. It is confirmed that there are significant differences whether the disturbances are added or not. The inflow forcing parameter that has the most influence on the flow and sound field is the azimuthal modes. It is shown that the inflow forcing takes an important role to destroy the coherence of velocity disturbances on the shear layer and prevents high amplitude velocity and pressure fluctuations that are caused due to axisymmetric vortices. When first modes in several azimuthal modes are removed, the flow field and far field sound pressure levels are relatively consistent with experimental data.
{"title":"高亜音速ジェット騒音のLarge-Eddy Simulationにおける入口擾乱の影響","authors":"勇也 福田, 進 寺本, 光司 岡本, 佑太 中西, 利夫 長島","doi":"10.2322/JJSASS.58.109","DOIUrl":"https://doi.org/10.2322/JJSASS.58.109","url":null,"abstract":"Subsonic jets at Mach number Mj = 0.9 are computed using compressible Large Eddy Simulation and Kirchhoff method in order to investigate the effects of the inflow forcing on the flow and sound field. Four parameters are varied in the jet inflow: the use of the first modes in the ring vortex excitation involving several azimuthal modes, the forcing amplitude, the thickness of disturbances, and the existence of the inflow forcing. It is confirmed that there are significant differences whether the disturbances are added or not. The inflow forcing parameter that has the most influence on the flow and sound field is the azimuthal modes. It is shown that the inflow forcing takes an important role to destroy the coherence of velocity disturbances on the shear layer and prevents high amplitude velocity and pressure fluctuations that are caused due to axisymmetric vortices. When first modes in several azimuthal modes are removed, the flow field and far field sound pressure levels are relatively consistent with experimental data.","PeriodicalId":144591,"journal":{"name":"Journal of The Japan Society for Aeronautical and Space Sciences","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124467366","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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