Aiming at the problem that the triaxial geomagnetic attitude measurement model can not directly figure out the complete attitude information of rotating missile or the current attitude calculation by limit ratio and integral ratio method needs calibration curves and look-up table method, after establishing missile-borne geomagnetic attitude measurement model and missile-borne infrared attitude measurement model respectively, a biaxial infrared and geomagnetic composite attitude measurement method is proposed. By the biaxial infrared attitude measurement model, the pitch angle and roll angle can be directly calculated. Combined with the biaxial geomagnetic attitude measurement model, the heading angle can be worked out finally. Through error transfer theory analysis, the direct calculation of pitch angle and roll angle is realized by alternating solution to reduce the measurement error. According to the analysis of the experimental data, the feasibility of the biaxial infrared and geomagnetic attitude measurement method is verified. And the direct calculation errors of pitch angle, roll angle and heading angle are respectively within ±0.8°, ±0.5° and ±1°. The biaxial infrared and geomagnetic attitude measurement method is simple and effective, which can meet the attitude measurement requirements of rotating projectile.
{"title":"A Biaxial Infrared and Geomagnetic Composite Attitude Measurement Method of Rotating Projectile","authors":"Yihan Cao, X. Bu, Wei Han, Zilu He","doi":"10.1115/imece2019-10492","DOIUrl":"https://doi.org/10.1115/imece2019-10492","url":null,"abstract":"\u0000 Aiming at the problem that the triaxial geomagnetic attitude measurement model can not directly figure out the complete attitude information of rotating missile or the current attitude calculation by limit ratio and integral ratio method needs calibration curves and look-up table method, after establishing missile-borne geomagnetic attitude measurement model and missile-borne infrared attitude measurement model respectively, a biaxial infrared and geomagnetic composite attitude measurement method is proposed. By the biaxial infrared attitude measurement model, the pitch angle and roll angle can be directly calculated. Combined with the biaxial geomagnetic attitude measurement model, the heading angle can be worked out finally. Through error transfer theory analysis, the direct calculation of pitch angle and roll angle is realized by alternating solution to reduce the measurement error. According to the analysis of the experimental data, the feasibility of the biaxial infrared and geomagnetic attitude measurement method is verified. And the direct calculation errors of pitch angle, roll angle and heading angle are respectively within ±0.8°, ±0.5° and ±1°. The biaxial infrared and geomagnetic attitude measurement method is simple and effective, which can meet the attitude measurement requirements of rotating projectile.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117212444","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 framework to develop data-driven parametric reduced order models (PROMs) for aeroelastic (AE) analysis of flexible vehicles within a broad flight envelop. It is based on the separate domain and mode shape perturbation method. The flight envelop is first partitioned by multiple grid points, on each of which an aerodynamic ROM (AeroROM) is constructed using system identification (SYSID) techniques to capture dependence of the generalized aerodynamic force on the generalized displacement using data generated by high-fidelity CFD simulation. Then AeroROMs not on the grid point are obtained by interpolating those at neighboring grid points. Two interpolation schemes, i.e., the output-based interpolation and coefficient interpolation are developed. The parametric AeroROM is then coupled with the mode-based structural ROMs to enable integrated AE analysis under various flight conditions. The state consistence enabled by different SYSID techniques and performance of both ROM interpolation methods are also investigated. For the first time, it is found that the autoregressive exogenous ROM allows state consistence and direct model coefficient interpolation. The ROMs exhibit excellent agreement with CFD simulations (< 3% relative error) and orders of magnitudes speedup. The effort opens up new opportunities for parametric AE analysis and flight control design.
{"title":"Parametric Data-Driven Reduced Order Models With State Consistence for Aeroelastic Analysis","authors":"William C. Krolick, Yi Wang, K. Pant","doi":"10.1115/imece2019-11333","DOIUrl":"https://doi.org/10.1115/imece2019-11333","url":null,"abstract":"This paper presents a framework to develop data-driven parametric reduced order models (PROMs) for aeroelastic (AE) analysis of flexible vehicles within a broad flight envelop. It is based on the separate domain and mode shape perturbation method. The flight envelop is first partitioned by multiple grid points, on each of which an aerodynamic ROM (AeroROM) is constructed using system identification (SYSID) techniques to capture dependence of the generalized aerodynamic force on the generalized displacement using data generated by high-fidelity CFD simulation. Then AeroROMs not on the grid point are obtained by interpolating those at neighboring grid points. Two interpolation schemes, i.e., the output-based interpolation and coefficient interpolation are developed. The parametric AeroROM is then coupled with the mode-based structural ROMs to enable integrated AE analysis under various flight conditions. The state consistence enabled by different SYSID techniques and performance of both ROM interpolation methods are also investigated. For the first time, it is found that the autoregressive exogenous ROM allows state consistence and direct model coefficient interpolation. The ROMs exhibit excellent agreement with CFD simulations (< 3% relative error) and orders of magnitudes speedup. The effort opens up new opportunities for parametric AE analysis and flight control design.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125547315","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 compact propulsion systems for nano and micro satellites is nowadays a growing research topic. Actually, the availability of low cost materials able to withstand space operation is now becoming widespread technology. This democratization on the access to space was not followed with a corresponding availability of critical propulsion technologies. However, the availability of propulsion systems for this class of satellites will provide them with new possibilities in what relates to mission profiles. In the present work an electrospray will be analysed, in particular the flow in the nozzle. This flow is controlled by a mix of pressure and electrostatic field. A full EHD (electrohydrodynamics) computational model is developed that is integrated in a classic CFD code using user specified functions. The proposed computational model was able to compute the flowfield for the electrospray test case under consideration. A benchmark against experimental results, by comparing spray thruster droplet size, concluded that the numerical model can predict their size within an error of 5%.
{"title":"Flow Modelling of Propulsion Nozzles for Nano-Satellites","authors":"J. Marques, G. Ribeiro, F. Brójo","doi":"10.1115/imece2019-11712","DOIUrl":"https://doi.org/10.1115/imece2019-11712","url":null,"abstract":"\u0000 The development of compact propulsion systems for nano and micro satellites is nowadays a growing research topic. Actually, the availability of low cost materials able to withstand space operation is now becoming widespread technology. This democratization on the access to space was not followed with a corresponding availability of critical propulsion technologies. However, the availability of propulsion systems for this class of satellites will provide them with new possibilities in what relates to mission profiles. In the present work an electrospray will be analysed, in particular the flow in the nozzle. This flow is controlled by a mix of pressure and electrostatic field. A full EHD (electrohydrodynamics) computational model is developed that is integrated in a classic CFD code using user specified functions. The proposed computational model was able to compute the flowfield for the electrospray test case under consideration. A benchmark against experimental results, by comparing spray thruster droplet size, concluded that the numerical model can predict their size within an error of 5%.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122194397","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}
Ryan P. Gilligan, Ian J. Jakupca, Phillip Smith, W. Bennett, M. Guzik, H. Kacher
In 2016, the National Aeronautics and Space Administration (NASA) Advanced Exploration Systems (AES) project office funded testing at the NASA Glenn Research Center to evaluate the maturity of the Proton Exchange Membrane (PEM) fuel cell technology and its viability for supporting launch vehicle and space applications. This technology evaluation included vibration, reactant purity, and vacuum exposure sensitivity testing. The evaluation process did not include microgravity testing. This paper discusses the vibration sensitivity testing of two air-independent fuel cell stacks provided by different vendors to assess the ability of currently available fuel cell stack hardware to survive the projected random vibrational environment that would be encountered in an upper stage launch vehicle. Baseline performance testing was utilized to quantify stack performance and overboard leak rate at standard atmospheric conditions in order to provide a reference for posttest comparison. Both fuel cell stacks were tested at a random vibration qualification level of 10.4 grms for five minutes in each axis. Low-level sinusoidal sweeps were conducted before and after each random vibration level run to see if any significant change in resonances were detected. Following vibration facility testing, the baseline performance testing was repeated. Test results demonstrated no measurable change in fuel cell electrochemical or mechanical performance, indicating that the two evaluated PEM fuel cell stacks may be suitable for space applications pending microgravity testing.
{"title":"Structural Dynamic Testing Results for Air-Independent Proton Exchange Membrane (PEM) Fuel Cell Technologies for Space Applications","authors":"Ryan P. Gilligan, Ian J. Jakupca, Phillip Smith, W. Bennett, M. Guzik, H. Kacher","doi":"10.1115/imece2019-11691","DOIUrl":"https://doi.org/10.1115/imece2019-11691","url":null,"abstract":"\u0000 In 2016, the National Aeronautics and Space Administration (NASA) Advanced Exploration Systems (AES) project office funded testing at the NASA Glenn Research Center to evaluate the maturity of the Proton Exchange Membrane (PEM) fuel cell technology and its viability for supporting launch vehicle and space applications. This technology evaluation included vibration, reactant purity, and vacuum exposure sensitivity testing. The evaluation process did not include microgravity testing. This paper discusses the vibration sensitivity testing of two air-independent fuel cell stacks provided by different vendors to assess the ability of currently available fuel cell stack hardware to survive the projected random vibrational environment that would be encountered in an upper stage launch vehicle. Baseline performance testing was utilized to quantify stack performance and overboard leak rate at standard atmospheric conditions in order to provide a reference for posttest comparison. Both fuel cell stacks were tested at a random vibration qualification level of 10.4 grms for five minutes in each axis. Low-level sinusoidal sweeps were conducted before and after each random vibration level run to see if any significant change in resonances were detected. Following vibration facility testing, the baseline performance testing was repeated. Test results demonstrated no measurable change in fuel cell electrochemical or mechanical performance, indicating that the two evaluated PEM fuel cell stacks may be suitable for space applications pending microgravity testing.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115922071","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}
With more than two billion passengers annually, in-flight transmission of infectious diseases is a major global health concern. It is widely believed that principal transmission risk associated with air travel for most respiratory infectious diseases is limited to within two rows of an infectious passenger. However, several passengers became infected despite sitting several rows away from the contagious passenger. This work thoroughly investigated the potential for disease spread inside airplane cabins using tracer gas to quantify airborne dispersion. Measurements were conducted in a full-scale, 11-row mock-up of a wide-body aircraft cabin. Heated mannequins to simulate passengers’ thermal load were placed on the cabin seats. Tracer gas was injected at the breathing level at four different hypothetical contagious passenger locations. The tracer gas concentration was measured radially up to 3.35 m away from the injection location representing four rows of a standard aircraft. A four-port sampling tree was used to collect samples at the breathing level at four different radial locations simultaneously. Each port was sampled for 30 minutes. A total of 42 tests were conducted in matching pairs to alleviate potential statistical or measurements bias. The results showed that the airflow pattern inside the mock-up airplane cabin plays a major role in determining tracer gas concentration meaning that the concentration at the same radial distance in different directions are not necessarily the same. Also, due to the air distribution pattern and cabin walls, concentrations at some seats may be higher than the source seat.
{"title":"Mapping the Potential for Infectious Disease Transmission in a Wide-Body Aircraft Cabin","authors":"Seif Mahmoud, J. Bennett, M. Hosni, B. Jones","doi":"10.1115/imece2019-11377","DOIUrl":"https://doi.org/10.1115/imece2019-11377","url":null,"abstract":"\u0000 With more than two billion passengers annually, in-flight transmission of infectious diseases is a major global health concern. It is widely believed that principal transmission risk associated with air travel for most respiratory infectious diseases is limited to within two rows of an infectious passenger. However, several passengers became infected despite sitting several rows away from the contagious passenger.\u0000 This work thoroughly investigated the potential for disease spread inside airplane cabins using tracer gas to quantify airborne dispersion. Measurements were conducted in a full-scale, 11-row mock-up of a wide-body aircraft cabin. Heated mannequins to simulate passengers’ thermal load were placed on the cabin seats. Tracer gas was injected at the breathing level at four different hypothetical contagious passenger locations. The tracer gas concentration was measured radially up to 3.35 m away from the injection location representing four rows of a standard aircraft. A four-port sampling tree was used to collect samples at the breathing level at four different radial locations simultaneously. Each port was sampled for 30 minutes.\u0000 A total of 42 tests were conducted in matching pairs to alleviate potential statistical or measurements bias. The results showed that the airflow pattern inside the mock-up airplane cabin plays a major role in determining tracer gas concentration meaning that the concentration at the same radial distance in different directions are not necessarily the same. Also, due to the air distribution pattern and cabin walls, concentrations at some seats may be higher than the source seat.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131591572","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}
D. Cristillo, Roberto Scigliano, S. D. Benedetto, S. Cardone, M. Appolloni, A. Jaskó
The purpose of this paper is to describe the procedures used to evaluate structural and thermal loads experimented by the HEXAFLY-INT Experimental Flight Test Vehicle (EFTV) and Experimental Service Module (ESM) during the ascent phase of the flight trajectory. The HEXAFLY-INT payload will be launched by a rocket in a suborbital trajectory having an apogee at around 90 km and Mach 8. During this phase the structure is subjected to the launcher environment that includes several events which generates static, random and sinusoidal acceleration and by a fixed thermal distribution. The load conditions due to mechanical loads have been defined by dynamic analyses by means of MSC Nastran software. Thermal loads have been identified by using Ansys Workbench software. The thermo-structural load conditions due to launcher environment have been defined by means of an interpolation procedure for transferring thermal distribution from Ansys to the Nastran FE Model.
{"title":"Structural and Thermal Loads for Hypersonic HEXAFLY-INT Vehicle","authors":"D. Cristillo, Roberto Scigliano, S. D. Benedetto, S. Cardone, M. Appolloni, A. Jaskó","doi":"10.1115/imece2019-10577","DOIUrl":"https://doi.org/10.1115/imece2019-10577","url":null,"abstract":"\u0000 The purpose of this paper is to describe the procedures used to evaluate structural and thermal loads experimented by the HEXAFLY-INT Experimental Flight Test Vehicle (EFTV) and Experimental Service Module (ESM) during the ascent phase of the flight trajectory.\u0000 The HEXAFLY-INT payload will be launched by a rocket in a suborbital trajectory having an apogee at around 90 km and Mach 8. During this phase the structure is subjected to the launcher environment that includes several events which generates static, random and sinusoidal acceleration and by a fixed thermal distribution. The load conditions due to mechanical loads have been defined by dynamic analyses by means of MSC Nastran software. Thermal loads have been identified by using Ansys Workbench software.\u0000 The thermo-structural load conditions due to launcher environment have been defined by means of an interpolation procedure for transferring thermal distribution from Ansys to the Nastran FE Model.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131074520","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}
Plasma actuators are very simple devices which have been shown to be effective in a wide variety of applications, such as separation control, wake control, aircraft noise reduction, modification of velocity fluctuations and boundary layer control. More recently, it has been also proved their ability for applications within the heat transfer field, such as film cooling of turbine blades or ice accumulation prevention. These simple devices are inexpensive, present robustness, low weight and are fully electronic. Considering the importance of these devices, the improvement of their efficiency is a subject of great interest for worldwide scientific community. It is known that, by reducing the plasma actuator dielectric thickness, the induced flow velocity increases. However, it is also known that, thin plasma actuators present short lifetime and quick dielectric layer degradation. Till now, only actuators with constant dielectric thickness have been studied. In the present work, a new concept of plasma actuator is studied: The stair shaped dielectric barrier discharge plasma actuator. This new device present a dielectric layer which provides a decrease of the dielectric thickness along the covered electrode width. This lead to an extended plasma discharge and an increase of the induced flow velocity and efficiency. In addition, the plasma discharge is weakened on the onset of plasma formation which prevents the quick degradation of the dielectric layer and leads to an increased actuator lifetime.
{"title":"Plasma Actuators Optimization Using Stair Shaped Dielectric Layers","authors":"F. Rodrigues, J. Marques, M. Trancossi","doi":"10.1115/imece2019-11515","DOIUrl":"https://doi.org/10.1115/imece2019-11515","url":null,"abstract":"\u0000 Plasma actuators are very simple devices which have been shown to be effective in a wide variety of applications, such as separation control, wake control, aircraft noise reduction, modification of velocity fluctuations and boundary layer control. More recently, it has been also proved their ability for applications within the heat transfer field, such as film cooling of turbine blades or ice accumulation prevention. These simple devices are inexpensive, present robustness, low weight and are fully electronic. Considering the importance of these devices, the improvement of their efficiency is a subject of great interest for worldwide scientific community. It is known that, by reducing the plasma actuator dielectric thickness, the induced flow velocity increases. However, it is also known that, thin plasma actuators present short lifetime and quick dielectric layer degradation. Till now, only actuators with constant dielectric thickness have been studied. In the present work, a new concept of plasma actuator is studied: The stair shaped dielectric barrier discharge plasma actuator. This new device present a dielectric layer which provides a decrease of the dielectric thickness along the covered electrode width. This lead to an extended plasma discharge and an increase of the induced flow velocity and efficiency. In addition, the plasma discharge is weakened on the onset of plasma formation which prevents the quick degradation of the dielectric layer and leads to an increased actuator lifetime.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"36 21","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120818044","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}
Among the recent research Friction-Stir-Welding (FSW) has been adopted worldwide as one of the dominant processes for welding lightweight aerospace Aluminum alloys. Al-2195 which is one of the new generation Aluminum alloys has been used in the external tank of the space shuttles. Aerospace fabricators are continuously pursuing FSW-technologies in its efforts to advance fabrication of the external tanks of the space shuttles. The future launch vehicles with reusable mandates require the structures to have excellent fatigue properties and improved fatigue lives. The butt-welded specimens of Al-2195 and Al-2219 are fatigue tested according to ASTM-E647. The effects of stress ratios, use of corrosion preventive compound (CPC), and the applications of periodic overloading on fatigue lives are investigated in this study. Scanning-electron-microscopy (SEM) is used to examine the criticality of the failure surfaces and the different modes of crack propagation that could have been initiated into the materials. It is found that fatigue life increases with the increase in stress ratio, and results show an increase in fatigue life ranging over 30% with the use of CPC, and the fatigue life increases even further with periodic overloading; whereas crack-closure phenomenon predominates the fatigue fracture. Fracture mechanics analysis and crack similitude was modified for fatigue cracks by Paris. Numerical studies using FEA has produced a model for fatigue life prediction scheme for these structures, where a novel strategy of the interface element technique with critical bonding strength criterion for formation of new fracture surfaces has been used to model fatigue crack propagation lives. The linear elastic fracture mechanics stress intensity factor is calculated using FEA and the fatigue life predictions made using this method are within 10–20% of the experimental fatigue life data obtained. This method overcomes the limitation of the traditional node-release scheme and closely matches the physics of the crack propagation.
{"title":"Fatigue Modeling of Friction-Stir-Welded (FSW) Butt-Joints for Aerospace Applications","authors":"M. A. Wahab, V. Raghuram","doi":"10.1115/imece2019-11723","DOIUrl":"https://doi.org/10.1115/imece2019-11723","url":null,"abstract":"\u0000 Among the recent research Friction-Stir-Welding (FSW) has been adopted worldwide as one of the dominant processes for welding lightweight aerospace Aluminum alloys. Al-2195 which is one of the new generation Aluminum alloys has been used in the external tank of the space shuttles. Aerospace fabricators are continuously pursuing FSW-technologies in its efforts to advance fabrication of the external tanks of the space shuttles. The future launch vehicles with reusable mandates require the structures to have excellent fatigue properties and improved fatigue lives. The butt-welded specimens of Al-2195 and Al-2219 are fatigue tested according to ASTM-E647. The effects of stress ratios, use of corrosion preventive compound (CPC), and the applications of periodic overloading on fatigue lives are investigated in this study. Scanning-electron-microscopy (SEM) is used to examine the criticality of the failure surfaces and the different modes of crack propagation that could have been initiated into the materials. It is found that fatigue life increases with the increase in stress ratio, and results show an increase in fatigue life ranging over 30% with the use of CPC, and the fatigue life increases even further with periodic overloading; whereas crack-closure phenomenon predominates the fatigue fracture. Fracture mechanics analysis and crack similitude was modified for fatigue cracks by Paris. Numerical studies using FEA has produced a model for fatigue life prediction scheme for these structures, where a novel strategy of the interface element technique with critical bonding strength criterion for formation of new fracture surfaces has been used to model fatigue crack propagation lives. The linear elastic fracture mechanics stress intensity factor is calculated using FEA and the fatigue life predictions made using this method are within 10–20% of the experimental fatigue life data obtained. This method overcomes the limitation of the traditional node-release scheme and closely matches the physics of the crack propagation.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130243467","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}
M. S. Rahman, P. Schilling, P. Herrington, U. Chakravarty
Selective laser melting (SLM) is a growing additive manufacturing (AM) technology which is capable of rapidly fabricating functional components in the medical and aviation industries. The thermophysical properties and melt-pool dynamics involved in the powder-bed SLM process play a crucial role to determine the part quality and process optimization. In this study, a 3-D computational fluid dynamics (CFD) model with Cu-Cr-Zr (C-18150) powder-bed is developed incorporating a moving conical volumetric heat source and temperature-dependent thermal properties to conduct the Multiphysics simulations of the SLM process. The melt-pool dynamics and its thermal behavior are investigated numerically and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and velocity in the melt pool are obtained for different laser beam specifications. The validation of the CFD model is conducted by comparing the simulation results for temperature and the melt-front motion with the analytical results found from the classical Stefan problem of the phase-change material. Studying the process parameters, melt-pool geometry, and thermal behavior of Cu-Cr-Zr alloy can generate valuable information to establish Cu-Cr-Zr as a low-cost engineering material in the AM industry.
{"title":"Thermal Behavior and Melt-Pool Dynamics of Cu-Cr-Zr Alloy in Powder-Bed Selective Laser Melting Process","authors":"M. S. Rahman, P. Schilling, P. Herrington, U. Chakravarty","doi":"10.1115/imece2019-11087","DOIUrl":"https://doi.org/10.1115/imece2019-11087","url":null,"abstract":"\u0000 Selective laser melting (SLM) is a growing additive manufacturing (AM) technology which is capable of rapidly fabricating functional components in the medical and aviation industries. The thermophysical properties and melt-pool dynamics involved in the powder-bed SLM process play a crucial role to determine the part quality and process optimization. In this study, a 3-D computational fluid dynamics (CFD) model with Cu-Cr-Zr (C-18150) powder-bed is developed incorporating a moving conical volumetric heat source and temperature-dependent thermal properties to conduct the Multiphysics simulations of the SLM process. The melt-pool dynamics and its thermal behavior are investigated numerically and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and velocity in the melt pool are obtained for different laser beam specifications. The validation of the CFD model is conducted by comparing the simulation results for temperature and the melt-front motion with the analytical results found from the classical Stefan problem of the phase-change material. Studying the process parameters, melt-pool geometry, and thermal behavior of Cu-Cr-Zr alloy can generate valuable information to establish Cu-Cr-Zr as a low-cost engineering material in the AM industry.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122183347","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}
Ni Li, Salla Kim, Jason Lin, Benjamin De La Torre, Manhong Wong, He Shen, Vimal Patel
Solar sailing has been increasingly considered for future space missions as an alternative method of propulsion, since it uses radiation pressure exerted by sunlight on a large mirrored surface for thrust and it does not require propellants such as chemicals or compressed gasses. For decades, single solar sail designs and deployment mechanisms have been studied and implemented in several CubeSats with the purpose of propulsion or deorbiting. Recently, a distributed four sail design has been proposed. The distributed four sails would have the potential to not only provide the spacecraft with propulsion force for space travel, but also control the attitude of the spacecraft by the coordinated motion of the four sails. Considering the large dimensions of the sails, it is necessary for the solar sails to be effectively stowed before launch and then deployed in a controlled manner in space. In this paper, the mechanical design of a deployment system that can stow and deploy four independent triangular solar sails with the ability to rotate after deployment will be presented. To demonstrate the effectiveness and the feasibility of the design, a prototype has been developed and validated through theoretical analysis and experimental tests.
{"title":"Mechanical Design of Distributed Solar Sail Deployment Systems","authors":"Ni Li, Salla Kim, Jason Lin, Benjamin De La Torre, Manhong Wong, He Shen, Vimal Patel","doi":"10.1115/imece2019-11968","DOIUrl":"https://doi.org/10.1115/imece2019-11968","url":null,"abstract":"\u0000 Solar sailing has been increasingly considered for future space missions as an alternative method of propulsion, since it uses radiation pressure exerted by sunlight on a large mirrored surface for thrust and it does not require propellants such as chemicals or compressed gasses. For decades, single solar sail designs and deployment mechanisms have been studied and implemented in several CubeSats with the purpose of propulsion or deorbiting. Recently, a distributed four sail design has been proposed. The distributed four sails would have the potential to not only provide the spacecraft with propulsion force for space travel, but also control the attitude of the spacecraft by the coordinated motion of the four sails. Considering the large dimensions of the sails, it is necessary for the solar sails to be effectively stowed before launch and then deployed in a controlled manner in space. In this paper, the mechanical design of a deployment system that can stow and deploy four independent triangular solar sails with the ability to rotate after deployment will be presented. To demonstrate the effectiveness and the feasibility of the design, a prototype has been developed and validated through theoretical analysis and experimental tests.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126560659","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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