Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16793
T. Berger, Jeneva Horn, M. Tischler
This paper presents a systematic investigation of high-speed rotorcraft pitch-axis response types, command models, and handling-qualities specifications. The investigation was done using two Future Vertical Lift-relevant rotorcraft configurations—a lift offset coaxial helicopter with a pusher propeller and a tiltrotor. Five response types were investigated, consisting of: a pitch rate-command/attitude-hold response type typically used for rotorcraft, a pitch ratecommand/attitude-hold response type using a higher-order command model based on the conventional airplane pitch rate transfer function, a normal acceleration/angle-of-attack hold response type, a flight path rate command/flight path hold response type, and a “blended” flight path rate command response type which varies the command model bandwidth based on stick input size. Designs of varying levels of pitch attitude bandwidth, flight path bandwidth, control anticipation parameter, and pitch attitude dropback were evaluated in a piloted simulation experiment conducted at the Penn State Flight Simulator facility using two high-speed Mission Task Elements. The results of the piloted simulation suggest that both the pitch attitude bandwidth and the pitch attitude dropback requirements must be met for Level 1 handling qualities. In addition, the current fixed-wing boundary for pitch attitude dropback appears to be too loose for high speed rotorcraft, and should be tightened to better match with pilot ratings. A set of recommended specifications and associated updated Level boundaries is provided in the Appendix.
{"title":"High-Speed Rotorcraft Pitch Axis Response Type Investigation","authors":"T. Berger, Jeneva Horn, M. Tischler","doi":"10.4050/f-0077-2021-16793","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16793","url":null,"abstract":"\u0000 This paper presents a systematic investigation of high-speed rotorcraft pitch-axis response types, command models, and handling-qualities specifications. The investigation was done using two Future Vertical Lift-relevant rotorcraft configurations—a lift offset coaxial helicopter with a pusher propeller and a tiltrotor. Five response types were investigated, consisting of: a pitch rate-command/attitude-hold response type typically used for rotorcraft, a pitch ratecommand/attitude-hold response type using a higher-order command model based on the conventional airplane pitch rate transfer function, a normal acceleration/angle-of-attack hold response type, a flight path rate command/flight path hold response type, and a “blended” flight path rate command response type which varies the command model bandwidth based on stick input size. Designs of varying levels of pitch attitude bandwidth, flight path bandwidth, control anticipation parameter, and pitch attitude dropback were evaluated in a piloted simulation experiment conducted at the Penn State Flight Simulator facility using two high-speed Mission Task Elements. The results of the piloted simulation suggest that both the pitch attitude bandwidth and the pitch attitude dropback requirements must be met for Level 1 handling qualities. In addition, the current fixed-wing boundary for pitch attitude dropback appears to be too loose for high speed rotorcraft, and should be tightened to better match with pilot ratings. A set of recommended specifications and associated updated Level boundaries is provided in the Appendix.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114607350","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16900
M. Gurvich
The objective of this work is a definition of a decision-making framework for reliability-driven assessment and corresponding methods of solutions, considering uncertainty, structural/material imperfections, missed information, randomness of input data, etc. More specifically, such framework is proposed to integrate critical steps including design, analysis, and experimental characterization and is suggested for typical rotorcraft and aircraft structures. The paper highlights details of the framework, key questions to address and proposed decision-making checklist for the assessment. Demonstrations of the framework are shown on cases of analysis, representing real structures, and on design studies based on their system-level understanding. In addition, enhanced solutions are shown for experimental characterization, specifically focused on assessment of variability and imperfections.
{"title":"Reliability-Driven Analysis, Design and Characterization of Rotorcraft Structures: Decision-Making Framework","authors":"M. Gurvich","doi":"10.4050/f-0077-2021-16900","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16900","url":null,"abstract":"\u0000 The objective of this work is a definition of a decision-making framework for reliability-driven assessment and corresponding methods of solutions, considering uncertainty, structural/material imperfections, missed information, randomness of input data, etc. More specifically, such framework is proposed to integrate critical steps including design, analysis, and experimental characterization and is suggested for typical rotorcraft and aircraft structures. The paper highlights details of the framework, key questions to address and proposed decision-making checklist for the assessment. Demonstrations of the framework are shown on cases of analysis, representing real structures, and on design studies based on their system-level understanding. In addition, enhanced solutions are shown for experimental characterization, specifically focused on assessment of variability and imperfections.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114563658","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16896
Mithil Kamble, N. Koratkar, C. Picu
Carbon fiber reinforced composites (CFRP) are frequently used in rotorcraft components due to their high strength to weight ratio. Carbon fibers are the principal load carriers whereas polymer matrix provides structural integrity to the CFRP components. Fatigue failure originating in the matrix pose a design constraint on CFRP components. The fatigue failure originates in form of small scale sub-critical cracks which eventually grow into macroscopic cracks/shear localization resulting in eventual failure. Research efforts have been directed at improving fracture and fatigue performance of polymeric matrix by arresting incipient cracks. Thermoset polymers are widely used as matrix material as they posses superior strength due to high crosslinking density. However, since no self-healing mechanism operates in thermosets, damage is irreversibly accumulated over the life cycle of components. A new class of materials called vitrimers provide a novel approach to develop fatigue resistant CFRP. Vitrimers are associative covalent adaptive networks (CAN) which have reversible crosslinking reactions which can be activated by external energy stimulus like heat. As the crosslinked network is reversible, the incipient damage can be 'healed' by application of heat. In this work we explore the self-healing properties of vitrimer fabricated by the reaction of adipic acid and epoxy resin. The vitrimer is initially tested in static tests to probe mechanical properties, followed by fatigue experiments. The vitrimer is then used to make a vitrimeric CFRP (vCFRP) composite and is tested for its static and fatigue performance.
{"title":"Vitrimer Composites for Rotorcraft Components","authors":"Mithil Kamble, N. Koratkar, C. Picu","doi":"10.4050/f-0077-2021-16896","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16896","url":null,"abstract":"Carbon fiber reinforced composites (CFRP) are frequently used in rotorcraft components due to their high strength to weight ratio. Carbon fibers are the principal load carriers whereas polymer matrix provides structural integrity to the CFRP components. Fatigue failure originating in the matrix pose a design constraint on CFRP components. The fatigue failure originates in form of small scale sub-critical cracks which eventually grow into macroscopic cracks/shear localization resulting in eventual failure. Research efforts have been directed at improving fracture and fatigue performance of polymeric matrix by arresting incipient cracks. Thermoset polymers are widely used as matrix material as they posses superior strength due to high crosslinking density. However, since no self-healing mechanism operates in thermosets, damage is irreversibly accumulated over the life cycle of components. A new class of materials called vitrimers provide a novel approach to develop fatigue resistant CFRP. Vitrimers are associative covalent adaptive networks (CAN) which have reversible crosslinking reactions which can be activated by external energy stimulus like heat. As the crosslinked network is reversible, the incipient damage can be 'healed' by application of heat. In this work we explore the self-healing properties of vitrimer fabricated by the reaction of adipic acid and epoxy resin. The vitrimer is initially tested in static tests to probe mechanical properties, followed by fatigue experiments. The vitrimer is then used to make a vitrimeric CFRP (vCFRP) composite and is tested for its static and fatigue performance.","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117337074","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16738
T. Herrmann, J. Baeder, R. Celi
A multiobjective design optimization methodology is used to determine the trim controls that minimize power required, noise, and blade loads of a coaxial-pusher rotorcraft, and to quantify the trade-offs among those three objectives in the form of 3-dimensional Pareto frontiers. A moderate-fidelity simulation model is used, which includes blade flexibility and a free vortex rotor wake model. A hybrid optimizer is developed, which starts with a genetic algorithm and radial basis function-based response surfaces, and ends with a gradient-based refinement. A new gradient-based method for constrained multiobjective optimization is developed, based on an extension of the method of feasible directions. A new technique for the automatic interpretation of rotor maps, based on image analysis and k-means clustering is presented. A new technique based on a k-nearest neighbor algorithm predicts trimmability. These two techniques reduce the need for analyst intervention during the optimization and improve accuracy. Results are presented for a 6- and an 8-control effector coaxial configuration in high speed flight.
{"title":"Multidisciplinary Trim Analysis Using Improved Optimization, Image Analysis, and Machine Learning Algorithms ","authors":"T. Herrmann, J. Baeder, R. Celi","doi":"10.4050/f-0077-2021-16738","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16738","url":null,"abstract":"\u0000 A multiobjective design optimization methodology is used to determine the trim controls that minimize power required, noise, and blade loads of a coaxial-pusher rotorcraft, and to quantify the trade-offs among those three objectives in the form of 3-dimensional Pareto frontiers. A moderate-fidelity simulation model is used, which includes blade flexibility and a free vortex rotor wake model. A hybrid optimizer is developed, which starts with a genetic algorithm and radial basis function-based response surfaces, and ends with a gradient-based refinement. A new gradient-based method for constrained multiobjective optimization is developed, based on an extension of the method of feasible directions. A new technique for the automatic interpretation of rotor maps, based on image analysis and k-means clustering is presented. A new technique based on a k-nearest neighbor algorithm predicts trimmability. These two techniques reduce the need for analyst intervention during the optimization and improve accuracy. Results are presented for a 6- and an 8-control effector coaxial configuration in high speed flight.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"625 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128245672","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16890
N. Caldwell, David Rancourt, Peter McCurry, U. Stein
This paper introduces a new series-hybrid digital transmission technology for distributed propulsion systems offering a lower cost, a lighter weight and more environmental tolerance than series-electric-hybrid powertrains. In particular, this concept can be used on large multicopters for applications requiring long range, heavy payloads and continuous hover, such as offshore search and rescue, surveillance and logistics. The concept, design principles and analysis are described to allow component sizing and calculation of operating point under steady state and dynamic conditions. A design is described for a quadcopter with maximum take-off weight of 380kg, including a Rotax 915 engine, a Digital Displacement® hydraulic pump and bent-axis motors. The components of the propulsion system are described and compared to an equivalent electric system, showing lower cost and weight, and similar efficiency. A computationally efficient model is described of the rotor behavior allowing rapid simulation with accurate rotor loads. A 6 DOF vehicle simulation is described, including dynamics of the proposed system, coupled to a flight controller. Results show that such a standard flight controller can fly the proposed system under a range of conditions including at the engine power limit. The expected flight endurance of the 380kg quadcopter is over 6 hours and range over 1000km depending on payload. Test rigs are described, including at full scale for the 380 kg study, which demonstrate stable control of hover. Other applications for distributed propulsion are discussed.
{"title":"Digital Displacement Hydrostatic Transmission for Rotorcraft and Distributed Propulsion","authors":"N. Caldwell, David Rancourt, Peter McCurry, U. Stein","doi":"10.4050/f-0077-2021-16890","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16890","url":null,"abstract":"\u0000 This paper introduces a new series-hybrid digital transmission technology for distributed propulsion systems offering a lower cost, a lighter weight and more environmental tolerance than series-electric-hybrid powertrains. In particular, this concept can be used on large multicopters for applications requiring long range, heavy payloads and continuous hover, such as offshore search and rescue, surveillance and logistics. The concept, design principles and analysis are described to allow component sizing and calculation of operating point under steady state and dynamic conditions. A design is described for a quadcopter with maximum take-off weight of 380kg, including a Rotax 915 engine, a Digital Displacement® hydraulic pump and bent-axis motors. The components of the propulsion system are described and compared to an equivalent electric system, showing lower cost and weight, and similar efficiency. A computationally efficient model is described of the rotor behavior allowing rapid simulation with accurate rotor loads. A 6 DOF vehicle simulation is described, including dynamics of the proposed system, coupled to a flight controller. Results show that such a standard flight controller can fly the proposed system under a range of conditions including at the engine power limit. The expected flight endurance of the 380kg quadcopter is over 6 hours and range over 1000km depending on payload. Test rigs are described, including at full scale for the 380 kg study, which demonstrate stable control of hover. Other applications for distributed propulsion are discussed.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128592072","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16884
Matthew Tkac
As the complexity of systems and software increase, the need to determine specific test cases for the requirements as well determining a complete test suite become more complex and time consuming. Additionally, testing typically comes at the end of the process, increasing cost and schedule pressures in an effort to get to market. This paper will introduce a technique, process and toolset that can assist in making reducing the cost and schedule pressures of testing a system. According to an article written by Ricardo Queiroz, “One of the big questions tormenting all managers since the start of any project is: "when should we start testing?" (Another usual big question is "why should we care?" - because of the money involved, obviously) the question seems hard, if you do not find serious arguments to select the starting date. Let me help you. So, when should you start testing after months of hard work developing the product? The answer is simple: the test team should be involved from the beginning right to the end! And this recommendation is based on many factors: testing saves time, effort and (you guessed it!) - Money!"
{"title":"Embedded Software: Automating Tests From Hand-written Requirements","authors":"Matthew Tkac","doi":"10.4050/f-0077-2021-16884","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16884","url":null,"abstract":"\u0000 As the complexity of systems and software increase, the need to determine specific test cases for the requirements as well determining a complete test suite become more complex and time consuming. Additionally, testing typically comes at the end of the process, increasing cost and schedule pressures in an effort to get to market. This paper will introduce a technique, process and toolset that can assist in making reducing the cost and schedule pressures of testing a system. According to an article written by Ricardo Queiroz, “One of the big questions tormenting all managers since the start of any project is: \"when should we start testing?\" (Another usual big question is \"why should we care?\" - because of the money involved, obviously) the question seems hard, if you do not find serious arguments to select the starting date. Let me help you. So, when should you start testing after months of hard work developing the product? The answer is simple: the test team should be involved from the beginning right to the end! And this recommendation is based on many factors: testing saves time, effort and (you guessed it!) - Money!\"\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127103357","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16837
N. Watson, I. Owen, M. White
This paper describes an investigation into the effect that turbulence in the air flow approaching an aircraft carrier has on the airwake over the flight deck and, subsequently, on helicopter recovery. CFD was used to generate the unsteady air flow over a full-scale Queen Elizabeth class aircraft carrier in a wind approaching 10° off the port-side. A steady inlet velocity profile was used for the approaching wind and an array of blocks was placed upstream of the ship to create a turbulent air flow. Thirty seconds of unsteady CFD has been integrated with a helicopter flight dynamic model to create a simulation environment in which real-time piloted flight trials were conducted. Pilot workload and DIPES ratings were obtained during the trial, which along with recorded trial data, was used to analyse the effect of the inlet conditions on the helicopter and pilot workload. The results show that while the turbulence in the air flow approaching the ship did affect the flow field over the flight deck, there was less effect on the workload experienced by the pilot during simulated deck landings.
{"title":"The Effect of Atmospheric Turbulence on Helicopter Recovery to a Twin-Island Aircraft Carrier","authors":"N. Watson, I. Owen, M. White","doi":"10.4050/f-0077-2021-16837","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16837","url":null,"abstract":"\u0000 This paper describes an investigation into the effect that turbulence in the air flow approaching an aircraft carrier has on the airwake over the flight deck and, subsequently, on helicopter recovery. CFD was used to generate the unsteady air flow over a full-scale Queen Elizabeth class aircraft carrier in a wind approaching 10° off the port-side. A steady inlet velocity profile was used for the approaching wind and an array of blocks was placed upstream of the ship to create a turbulent air flow. Thirty seconds of unsteady CFD has been integrated with a helicopter flight dynamic model to create a simulation environment in which real-time piloted flight trials were conducted. Pilot workload and DIPES ratings were obtained during the trial, which along with recorded trial data, was used to analyse the effect of the inlet conditions on the helicopter and pilot workload. The results show that while the turbulence in the air flow approaching the ship did affect the flow field over the flight deck, there was less effect on the workload experienced by the pilot during simulated deck landings.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"09 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127287932","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16875
M. Alexander, E. Perron, Perry Comeau, David Rancourt
The National Research Council of Canada and Université de Sherbrooke performed flight testing of an Actively Stabilized Slung Load on the NRC Bell 206 Research Aircraft. Hover, Attitude Capture, NRC designed Lateral Precision Hover, and Frequency Sweep mission tasks were performed for Bare Airframe, Passive Water-Filled Barrel and Active Slung Load configurations. Load Mass Ratios of 0.12 with pendulum modes of 1.3 rad/sec were identified for both configurations. Time domain response indicated that both loads remained controllable under excitation by pilot gain, winds, and helicopter-load mode coalescence. Frequency domain analyses confirmed pilot comments indicating HQR-4 handling qualities ratings for bare airframe and stable load behaviors. This degraded to HQR-5 for task execution with load oscillation effects rated at pilot induced oscillation tendency of PIO/T-4. Barrel load HQR degradation related to load inertial and surface area drag effects versus active tether feedback and roll-pitch actuation disharmony of the Active load. Though not optimized, this load’s swing behavior (consistent period and rate) can aid in management of aircraft rate response and pilot compensation. Overall, comparable passive and active test results indicate potential for magneto-rheological actuation to improve slung load mission task performance.
{"title":"Comparative Flight Test Evaluation of Passive and Active External Slung Load Dynamics","authors":"M. Alexander, E. Perron, Perry Comeau, David Rancourt","doi":"10.4050/f-0077-2021-16875","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16875","url":null,"abstract":"The National Research Council of Canada and Université de Sherbrooke performed flight testing of an Actively Stabilized Slung Load on the NRC Bell 206 Research Aircraft. Hover, Attitude Capture, NRC designed Lateral Precision Hover, and Frequency Sweep mission tasks were performed for Bare Airframe, Passive Water-Filled Barrel and Active Slung Load configurations. Load Mass Ratios of 0.12 with pendulum modes of 1.3 rad/sec were identified for both configurations. Time domain response indicated that both loads remained controllable under excitation by pilot gain, winds, and helicopter-load mode coalescence. Frequency domain analyses confirmed pilot comments indicating HQR-4 handling qualities ratings for bare airframe and stable load behaviors. This degraded to HQR-5 for task execution with load oscillation effects rated at pilot induced oscillation tendency of PIO/T-4. Barrel load HQR degradation related to load inertial and surface area drag effects versus active tether feedback and roll-pitch actuation disharmony of the Active load. Though not optimized, this load’s swing behavior (consistent period and rate) can aid in management of aircraft rate response and pilot compensation. Overall, comparable passive and active test results indicate potential for magneto-rheological actuation to improve slung load mission task performance.","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127455257","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16902
J. Lua, Jinhui Yan, A. Karuppiah, Peipei Li, M. Stuebner, Ze Zhao
Large aluminum forging parts are increasingly used in aerospace structures to enable structural unitization. In the fabrication of heat treatable aluminum parts for the aerospace industry, quenching is a crucial step to suppress the precipitation to retain the supersaturation of the solid solution, control the distortion, and minimize the residual stress in aluminum alloys. Because of the complex interaction between temperature, phase-transformation, and stress/strain relation that depends on the temperature distribution and the microstructure of the workpiece, there is no performance informed quenching process that can be applied reliably to reduce the high scrap rate of airframe aluminum forging parts with a significant amount of residual stress and distortion. The development of a quicker and more reliable qualification and certification procedure is so important given the stringent constraints on cost and schedule. The primary goal of this study is to develop a multi-physics tool to perform simulations with optimized quenching parameters to achieve minimum distortion. A high-fidelity thermal multi-phase fluid-structure interaction (FSI) model is applied to simulate fluid dynamics and temperature fields in the quenchant tank. The developed immersogeometric modeling approach is used next for an efficient model generation of a 3D workpiece with various dipping orientations. Given the temperature and pressure profiles predicted from the FSI based heat transfer module, residual stress and distortion prediction modules are developed by including temperature and pressure fields mapping and temperature and strain rate dependent property evolution via Abaqus’ userdefined subroutines. Verification and demonstration studies are performed using aluminum coupons dipped into a quenching tank of two different orientations with and without agitation. Time histories of the temperature and residual stress fields were predicted to explore the relationship between the process and performance.
{"title":"Novel Multi-Physics-based Modeling of a Quenching Process with Thermal-Metallurgical-Mechanical Interactions in Aluminum Component","authors":"J. Lua, Jinhui Yan, A. Karuppiah, Peipei Li, M. Stuebner, Ze Zhao","doi":"10.4050/f-0077-2021-16902","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16902","url":null,"abstract":"\u0000 Large aluminum forging parts are increasingly used in aerospace structures to enable structural unitization. In the fabrication of heat treatable aluminum parts for the aerospace industry, quenching is a crucial step to suppress the precipitation to retain the supersaturation of the solid solution, control the distortion, and minimize the residual stress in aluminum alloys. Because of the complex interaction between temperature, phase-transformation, and stress/strain relation that depends on the temperature distribution and the microstructure of the workpiece, there is no performance informed quenching process that can be applied reliably to reduce the high scrap rate of airframe aluminum forging parts with a significant amount of residual stress and distortion. The development of a quicker and more reliable qualification and certification procedure is so important given the stringent constraints on cost and schedule. The primary goal of this study is to develop a multi-physics tool to perform simulations with optimized quenching parameters to achieve minimum distortion. A high-fidelity thermal multi-phase fluid-structure interaction (FSI) model is applied to simulate fluid dynamics and temperature fields in the quenchant tank. The developed immersogeometric modeling approach is used next for an efficient model generation of a 3D workpiece with various dipping orientations. Given the temperature and pressure profiles predicted from the FSI based heat transfer module, residual stress and distortion prediction modules are developed by including temperature and pressure fields mapping and temperature and strain rate dependent property evolution via Abaqus’ userdefined subroutines. Verification and demonstration studies are performed using aluminum coupons dipped into a quenching tank of two different orientations with and without agitation. Time histories of the temperature and residual stress fields were predicted to explore the relationship between the process and performance.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127477666","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}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16860
Jonatan Campos, D. Cardoso, G. Raffo
A robust adaptive mixing controller (RAMC) is designed to solve the trajectory tracking problem of a quad-tiltrotor convertible plane (CP) unmanned aerial vehicle (UAV). This kind of system is a hybrid aerial vehicle that combines advantages of rotary and fixed-wing aircraft. In this work, the equations of motion of this UAV are obtained using the Euler-Lagrange formalism and assuming it as a multibody mechanical system. The non-conservative forces and torques generated by the propellers, servomotors and aerodynamic surfaces, are mapped to the generalized forces vector. Aiming to design the RAMC, an LPV representation of the system is derived from the nonlinear model, from which several mixed H2/H∞ candidate controllers are designed according to the UAV forward motion, and an adaptive mixing scheme is employed to smoothly interpolate these controllers, providing stability to the closed-loop system for the full-flight envelope of the UAV. The efficiency of the RAMC is verified in a high-fidelity simulator developed on the Gazebo and ROS platforms, in which the UAV is required to track a reference trajectory with different flight requirements, such as hovering, transition, cruise and level turn.
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