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1.
Galles, Matthew B.
Reducing the Noise Impact of Unmanned Aerial Vehicles by Flight Control System Augmentation.
Degree: MS, Mechanical & Aerospace Engineering, 2019, Old Dominion University
URL: 9798662496514
;
https://digitalcommons.odu.edu/mae_etds/317 
► The aim of this thesis is to explore methods to reduce the noise impact of unmanned aerial vehicles operating within acoustically sensitive environments by…
(more)
▼ The aim of this thesis is to explore methods to reduce the noise impact of unmanned aerial vehicles operating within acoustically sensitive environments by flight control system augmentation. Two methods are investigated and include: (i) reduction of sound generated by vehicle speed control while flying along a nominal path and (ii) reduction of acoustic exposure by vehicle path control while flying at a nominal speed. Both methods require incorporation of an acoustic model into the flight control system as an additional control objective and an acoustic metric to characterize primary noise sources dependent on vehicle state. An acoustic model was developed based on Gutin’s work to estimate propeller noise, both to estimate source noise and observer noise using two separate acoustic metrics. These methods can potentially mitigate the noise impact of unmanned aerial systems operating near residential communities.
The baseline flight control system of a representative aircraft was augmented with a control law to reduce propeller noise using feedback control of the commanded flight speed until an acoustic target was met, based on the propeller noise model. This control approach focuses on modifying flight speed only, with no perturbation to the trajectory. Multiple flight simulations were performed and the results showed that integrating an acoustic metric into the flight control system of an unmanned aerial system is possible and useful. A second method to mitigate the effects of noise on an observer was also pursued to optimize a trajectory in order to avoid an acoustically sensitive region during the path planning process. After the propeller noise model was incorporated into the vehicle system, simulations showed that it is possible to reduce the noise impact on an observer through an optimization of the trajectory with no perturbation to the flight speed.
Advisors/Committee Members: Brett Newman, Noah H. Schiller, Thomas E. Alberts.
Subjects/Keywords: Noise; Trajectory optimization; Unmanned aerial vehicles; Acoustics, Dynamics, and Controls; Aerospace Engineering; Applied Mechanics
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APA (6th Edition):
Galles, M. B. (2019). Reducing the Noise Impact of Unmanned Aerial Vehicles by Flight Control System Augmentation. (Thesis). Old Dominion University. Retrieved from 9798662496514 ; https://digitalcommons.odu.edu/mae_etds/317
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Galles, Matthew B. “Reducing the Noise Impact of Unmanned Aerial Vehicles by Flight Control System Augmentation.” 2019. Thesis, Old Dominion University. Accessed January 24, 2021.
9798662496514 ; https://digitalcommons.odu.edu/mae_etds/317.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Galles, Matthew B. “Reducing the Noise Impact of Unmanned Aerial Vehicles by Flight Control System Augmentation.” 2019. Web. 24 Jan 2021.
Vancouver:
Galles MB. Reducing the Noise Impact of Unmanned Aerial Vehicles by Flight Control System Augmentation. [Internet] [Thesis]. Old Dominion University; 2019. [cited 2021 Jan 24].
Available from: 9798662496514 ; https://digitalcommons.odu.edu/mae_etds/317.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Galles MB. Reducing the Noise Impact of Unmanned Aerial Vehicles by Flight Control System Augmentation. [Thesis]. Old Dominion University; 2019. Available from: 9798662496514 ; https://digitalcommons.odu.edu/mae_etds/317
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
2.
Simsek, Mehmet R.
A Hybrid Position Feedback Controller for Bistable Structures.
Degree: MS, Mechanical & Aerospace Engineering, 2016, Old Dominion University
URL: 9781339893877
;
https://digitalcommons.odu.edu/mae_etds/5
► Bistability is the property of structures showing the ability to attain two statically stable states. Due to dynamic and static advantages such as no…
(more)
▼ Bistability is the property of structures showing the ability to attain two statically stable states. Due to dynamic and static advantages such as no energy demand at stable positions and providing higher deflections compared to a monostable structure, bistability may be appealing in control surface design for aircraft structures and load alleviation for wind turbine blades. The dynamics of bistable structures is nonlinear because of the snap-through occurring during the cross-well oscillation between two stable states. A new control strategy called hybrid position feedback control is developed based on the conventional positive position control to exploit linear dynamics of bistable structures around stable equilibrium positions.
In this thesis, complementary stability, performance and energy analysis of bistable structures controlled by the hybrid controller are investigated using numerical time domain and frequency methods. The stability regions, energy variance by parameters, and the operational regions providing state transition are determined. As a result of the analyses, two alternative design options are proposed and necessary stability regions are indicated.
In addition, experimental analysis is conducted on an unsymmetric cross-ply bistable composite plate to show the feasibility of the hybrid control strategy. Various analyses such as stability and energy consumption are performed.
Advisors/Committee Members: Onur Bilgen, Thomas E. Alberts, Drew Landman.
Subjects/Keywords: Bistable structure; Hybrid feedback control; Morphing wing; Piezoletric actuation; Smart systems; Snap-through; Aerospace Engineering; Mechanical Engineering
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APA (6th Edition):
Simsek, M. R. (2016). A Hybrid Position Feedback Controller for Bistable Structures. (Thesis). Old Dominion University. Retrieved from 9781339893877 ; https://digitalcommons.odu.edu/mae_etds/5
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Simsek, Mehmet R. “A Hybrid Position Feedback Controller for Bistable Structures.” 2016. Thesis, Old Dominion University. Accessed January 24, 2021.
9781339893877 ; https://digitalcommons.odu.edu/mae_etds/5.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Simsek, Mehmet R. “A Hybrid Position Feedback Controller for Bistable Structures.” 2016. Web. 24 Jan 2021.
Vancouver:
Simsek MR. A Hybrid Position Feedback Controller for Bistable Structures. [Internet] [Thesis]. Old Dominion University; 2016. [cited 2021 Jan 24].
Available from: 9781339893877 ; https://digitalcommons.odu.edu/mae_etds/5.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Simsek MR. A Hybrid Position Feedback Controller for Bistable Structures. [Thesis]. Old Dominion University; 2016. Available from: 9781339893877 ; https://digitalcommons.odu.edu/mae_etds/5
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
3.
Abdallah, Ayman Muhammad.
Flight Dynamics Nonlinearity Assessment Across a New Aerodynamic Attitude Flight Envelope.
Degree: PhD, Aerospace Engineering, 2015, Old Dominion University
URL: 9781339125831
;
https://digitalcommons.odu.edu/mae_etds/107
► A new asymmetric level aerodynamic attitude flight envelope is introduced in this dissertation. The aerodynamic attitude envelope is an angle of attack vs. sideslip…
(more)
▼ A new asymmetric level aerodynamic attitude flight envelope is introduced in this dissertation. The aerodynamic attitude envelope is an angle of attack vs. sideslip angle region which describes the extent of where an aircraft can sustain a steady slipping horizontal flight condition. The new envelope is thus an extension of the more common speed-altitude symmetric level flight envelope. This new envelope can be used for design requirements, dynamic analysis, control synthesis, or performance comparison. Moreover, this envelope provides enhanced insight into trimability-controllability limitations within the aircraft design model. The aerodynamic attitude flight envelope is constructed for a six degree of freedom nonlinear simulation model of a high-performance aircraft. The constructed envelope is found to be asymmetric with respect to positive vs. negative sideslip values, due to the inherent asymmetry in the aerodynamic model database. Asymmetry and offset in the force and moment coefficient data could originate from experimental error, from model fabrication imperfections, from vortex-dominated flow, from data reduction flaws, or from other sources. The literature shows that vortex-dominated flow can cause significant side force, rolling moment, and yawing moment coefficient asymmetries. Details concerning the removal of asymmetry and offset in the aerodynamic data are given. The purpose behind removing the asymmetry and offset is to facilitate analysis of the new aerodynamic attitude flight envelope with an ideal aircraft model so that fundamental relationships can be more easily observed, and to provide a comparison with the non-ideal case previously computed. Based on the adapted and symmetrized aerodynamic data, a new aerodynamic attitude asymmetric level flight envelope is constructed and introduced.
Further, the six degree of freedom aircraft simulation model is analyzed with nonlinear index theory across this nontraditional flight envelope. Aircraft dynamic properties often change in a nonlinear way across operating conditions. Nonlinear index theory provides a new concept for measuring the strength of these changes for a given set of coordinates and is applied to the asymmetric aerodynamic attitude envelope with the original and the adapted and symmetrized aerodynamic data. This analysis provides new methodology and new insights into aircraft dynamics and control. The index analysis exposes certain flight condition regions in which nonlinearity strength is high. These regions are further investigated with both linear and nonlinear simulations. Because the nonlinearity index is based on the matrix two-norm, the index can sometimes overestimate the nonlinear strength. To circumvent this behavior, indices based on system matrix partitions and normalized state formulations are explored. Nonlinearity is a function of the coordinates used to express the dynamic system. Therefore, the nonlinearity index is also applied to the aircraft model, expressed with three different frame of reference sets for…
Advisors/Committee Members: Brett A. Newman, Thomas E. Alberts, Duc T. Nguyen.
Subjects/Keywords: Aerodynamic attitude flight envelope; Airplanes; Speed; Flight dynamics; Aerodynamics and Fluid Mechanics; Aerospace Engineering; Navigation, Guidance, Control and Dynamics
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APA (6th Edition):
Abdallah, A. M. (2015). Flight Dynamics Nonlinearity Assessment Across a New Aerodynamic Attitude Flight Envelope. (Doctoral Dissertation). Old Dominion University. Retrieved from 9781339125831 ; https://digitalcommons.odu.edu/mae_etds/107
Chicago Manual of Style (16th Edition):
Abdallah, Ayman Muhammad. “Flight Dynamics Nonlinearity Assessment Across a New Aerodynamic Attitude Flight Envelope.” 2015. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9781339125831 ; https://digitalcommons.odu.edu/mae_etds/107.
MLA Handbook (7th Edition):
Abdallah, Ayman Muhammad. “Flight Dynamics Nonlinearity Assessment Across a New Aerodynamic Attitude Flight Envelope.” 2015. Web. 24 Jan 2021.
Vancouver:
Abdallah AM. Flight Dynamics Nonlinearity Assessment Across a New Aerodynamic Attitude Flight Envelope. [Internet] [Doctoral dissertation]. Old Dominion University; 2015. [cited 2021 Jan 24].
Available from: 9781339125831 ; https://digitalcommons.odu.edu/mae_etds/107.
Council of Science Editors:
Abdallah AM. Flight Dynamics Nonlinearity Assessment Across a New Aerodynamic Attitude Flight Envelope. [Doctoral Dissertation]. Old Dominion University; 2015. Available from: 9781339125831 ; https://digitalcommons.odu.edu/mae_etds/107
4.
Tran, Thanh Trung.
Nonlinear Flight Control Design Using Backstepping Methodology.
Degree: PhD, Aerospace Engineering, 2016, Old Dominion University
URL: 9781369169768
;
https://digitalcommons.odu.edu/mae_etds/16
► The subject of nonlinear flight control design using backstepping control methodology is investigated in the dissertation research presented here. Control design methods based on…
(more)
▼ The subject of nonlinear flight control design using backstepping control methodology is investigated in the dissertation research presented here. Control design methods based on nonlinear models of the dynamic system provide higher utility and versatility because the design model more closely matches the physical system behavior. Obtaining requisite model fidelity is only half of the overall design process, however. Design of the nonlinear control loops can lessen the effects of nonlinearity, or even exploit nonlinearity, to achieve higher levels of closed-loop stability, performance, and robustness. The goal of the research is to improve control quality for a general class of strict-feedback dynamic systems and provide flight control architectures to augment the aircraft motion. The research is divided into two parts: theoretical control development for the strict-feedback form of nonlinear dynamic systems and application of the proposed theory for nonlinear flight dynamics. In the first part, the research is built on two components: transforming the nonlinear dynamic model to a canonical strict-feedback form and then applying backstepping control theory to the canonical model. The research considers a process to determine when this transformation is possible, and when it is possible, a systematic process to transfer the model is also considered when practical. When this is not the case, certain modeling assumptions are explored to facilitate the transformation. After achieving the canonical form, a systematic design procedure for formulating a backstepping control law is explored in the research. Starting with the simplest subsystem and ending with the full system, pseudo control concepts based on Lyapunov control functions are used to control each successive subsystem. Typically each pseudo control must be solved from a nonlinear algebraic equation. At the end of this process, the physical control input must be re-expressed in terms of the physical states by eliminating the pseudo control transformations. In the second part, the research focuses on nonlinear control design for flight dynamics of aircraft motion. Some assumptions on aerodynamics of the aircraft are addressed to transform full nonlinear flight dynamics into the canonical strict-feedback form. The assumptions are also analyzed, validated, and compared to show the advantages and disadvantages of the design models. With the achieved models, investigation focuses on formulating the backstepping control laws and provides an advanced control algorithm for nonlinear flight dynamics of the aircraft. Experimental and simulation studies are successfully implemented to validate the proposed control method. Advancement of nonlinear backstepping control theory and its application to nonlinear flight control are achieved in the dissertation research.
Advisors/Committee Members: Brett Newman, Thomas E. Alberts, Jen-Kuang Huang, Duc Nguyen.
Subjects/Keywords: Backstepping control; Lyapunov-Based Design; Nonlinear flight control; Aerospace Engineering; Navigation, Guidance, Control and Dynamics
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APA (6th Edition):
Tran, T. T. (2016). Nonlinear Flight Control Design Using Backstepping Methodology. (Doctoral Dissertation). Old Dominion University. Retrieved from 9781369169768 ; https://digitalcommons.odu.edu/mae_etds/16
Chicago Manual of Style (16th Edition):
Tran, Thanh Trung. “Nonlinear Flight Control Design Using Backstepping Methodology.” 2016. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9781369169768 ; https://digitalcommons.odu.edu/mae_etds/16.
MLA Handbook (7th Edition):
Tran, Thanh Trung. “Nonlinear Flight Control Design Using Backstepping Methodology.” 2016. Web. 24 Jan 2021.
Vancouver:
Tran TT. Nonlinear Flight Control Design Using Backstepping Methodology. [Internet] [Doctoral dissertation]. Old Dominion University; 2016. [cited 2021 Jan 24].
Available from: 9781369169768 ; https://digitalcommons.odu.edu/mae_etds/16.
Council of Science Editors:
Tran TT. Nonlinear Flight Control Design Using Backstepping Methodology. [Doctoral Dissertation]. Old Dominion University; 2016. Available from: 9781369169768 ; https://digitalcommons.odu.edu/mae_etds/16
5.
Mekky, Ahmed Elhussein E.
Modeling, Identification, Validation and Control of a Hybrid Maglev Ball System.
Degree: MS, Aerospace Engineering, 2012, Old Dominion University
URL: 9781267647719
;
https://digitalcommons.odu.edu/mae_etds/139
► In this thesis, the electrodynamics of a single axis hybrid electromagnetic suspension Maglev system was modeled and validated by applying it to a single…
(more)
▼ In this thesis, the electrodynamics of a single axis hybrid electromagnetic suspension Maglev system was modeled and validated by applying it to a single axis hybrid maglev ball experiment. By exploring its linearized model, it was shown that the single axis hybrid Maglev ball has inherently unstable dynamics. Three control scenarios were explored based on the linearized model; (1) Proportional, Deferential (PD) control, (2) Proportional, Deferential, Integral (PID) and (3) PID controller with pre-filtering. This thesis has shown that a PID controller with a pre-filtering technique can stabilize such a system and provide a well-controlled response.
A parametric system identification technique was applied to fit the theoretically derived model to a single axis hybrid maglev ball experiment. It is known that the identified model has different model parameters than the theoretically "derived" parameters. This thesis has examined and discussed the deviation from the theoretical model. Importantly, it was shown that such a system can be identified by estimating the values of two parameters instead of five to increase the accuracy.
A Numerical nonlinear simulation was developed for the experiment based on the theoretically derived and experimentally identified model. This simulation was validated by real-time experiment outputs.
Advisors/Committee Members: Thomas E. Alberts, Brett Newman, Colin P. Britcher, Robert L. Ash.
Subjects/Keywords: Electrodynamics; Magnetic levitation vehicles; Magnetic suspension; Aerospace Engineering; Automotive Engineering; Electromagnetics and Photonics; Electro-Mechanical Systems; Mechanical Engineering
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APA (6th Edition):
Mekky, A. E. E. (2012). Modeling, Identification, Validation and Control of a Hybrid Maglev Ball System. (Thesis). Old Dominion University. Retrieved from 9781267647719 ; https://digitalcommons.odu.edu/mae_etds/139
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Mekky, Ahmed Elhussein E. “Modeling, Identification, Validation and Control of a Hybrid Maglev Ball System.” 2012. Thesis, Old Dominion University. Accessed January 24, 2021.
9781267647719 ; https://digitalcommons.odu.edu/mae_etds/139.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Mekky, Ahmed Elhussein E. “Modeling, Identification, Validation and Control of a Hybrid Maglev Ball System.” 2012. Web. 24 Jan 2021.
Vancouver:
Mekky AEE. Modeling, Identification, Validation and Control of a Hybrid Maglev Ball System. [Internet] [Thesis]. Old Dominion University; 2012. [cited 2021 Jan 24].
Available from: 9781267647719 ; https://digitalcommons.odu.edu/mae_etds/139.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Mekky AEE. Modeling, Identification, Validation and Control of a Hybrid Maglev Ball System. [Thesis]. Old Dominion University; 2012. Available from: 9781267647719 ; https://digitalcommons.odu.edu/mae_etds/139
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
6.
Okasha, Mohamed Elsayed Aly Abd Elaziz.
Dynamics and Control of Satellite Relative Motion in Proximity Operations.
Degree: PhD, Aerospace Engineering, 2012, Old Dominion University
URL: 9781267350398
;
https://digitalcommons.odu.edu/mae_etds/150
► In this dissertation, the development of relative navigation, guidance, and control algorithms of an autonomous space rendezvous and docking system are presented. These algorithms…
(more)
▼ In this dissertation, the development of relative navigation, guidance, and control algorithms of an autonomous space rendezvous and docking system are presented. These algorithms are based on innovative formulations of the relative motion equations that are completely explicit in time. The navigation system uses an extended Kalman filter based on these formulations to estimate the relative position and velocity of the chaser vehicle with respect to the target vehicle and the chaser attitude and gyro biases. This filter uses the range and angle measurements of the target relative to the chaser from a simulated LIDAR system, along with the star tracker and gyro measurements of the chaser. The corresponding measurement models, process noise matrix, and other filter parameters are provided. The guidance and control algorithms are based on the glideslope used in the past for rendezvous and proximity operations of the Space Shuttle with other vehicles. These algorithms are used to approach, flyaround, and to depart from a target vehicle in elliptic orbits. The algorithms are general and able to translate the chaser vehicle in any direction, decelerate while approaching the target vehicle, and accelerate when moving away. Numerical nonlinear simulations that illustrate the relative navigation, attitude estimation, guidance, and control algorithm's, as well as performance and accuracy are evaluated in the research study.
Advisors/Committee Members: Brett A. Newman, Robert Ash, Thomas E. Alberts, Zhao Sun.
Subjects/Keywords: Orbit rendezvous; Proximity operations; Relative motion; Relative nevigation; Satellite formation; Space rendezvous; Aerospace Engineering; Electrical and Computer Engineering; Mechanical Engineering
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APA (6th Edition):
Okasha, M. E. A. A. E. (2012). Dynamics and Control of Satellite Relative Motion in Proximity Operations. (Doctoral Dissertation). Old Dominion University. Retrieved from 9781267350398 ; https://digitalcommons.odu.edu/mae_etds/150
Chicago Manual of Style (16th Edition):
Okasha, Mohamed Elsayed Aly Abd Elaziz. “Dynamics and Control of Satellite Relative Motion in Proximity Operations.” 2012. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9781267350398 ; https://digitalcommons.odu.edu/mae_etds/150.
MLA Handbook (7th Edition):
Okasha, Mohamed Elsayed Aly Abd Elaziz. “Dynamics and Control of Satellite Relative Motion in Proximity Operations.” 2012. Web. 24 Jan 2021.
Vancouver:
Okasha MEAAE. Dynamics and Control of Satellite Relative Motion in Proximity Operations. [Internet] [Doctoral dissertation]. Old Dominion University; 2012. [cited 2021 Jan 24].
Available from: 9781267350398 ; https://digitalcommons.odu.edu/mae_etds/150.
Council of Science Editors:
Okasha MEAAE. Dynamics and Control of Satellite Relative Motion in Proximity Operations. [Doctoral Dissertation]. Old Dominion University; 2012. Available from: 9781267350398 ; https://digitalcommons.odu.edu/mae_etds/150
7.
Mekky, Ahmed.
Design and Implementation of an Artificial Neural Network Controller for Quadrotor Flight in Confined Environment.
Degree: PhD, Aerospace Engineering, 2018, Old Dominion University
URL: 9780355884210
;
https://digitalcommons.odu.edu/mae_etds/35
► Quadrotors offer practical solutions for many applications, such as emergency rescue, surveillance, military operations, videography and many more. For this reason, they have recently…
(more)
▼ Quadrotors offer practical solutions for many applications, such as emergency rescue, surveillance, military operations, videography and many more. For this reason, they have recently attracted the attention of research and industry. Even though they have been intensively studied, quadrotors still suffer from some challenges that limit their use, such as trajectory measurement, attitude estimation, obstacle avoidance, safety precautions, and land cybersecurity. One major problem is flying in a confined environment, such as closed buildings and tunnels, where the aerodynamics around the quadrotor are affected by close proximity objects, which result in tracking performance deterioration, and sometimes instability. To address this problem, researchers followed three different approaches; the Modeling approach, which focuses on the development of a precise dynamical model that accounts for the different aerodynamic effects, the Sensor Integration approach, which focuses on the addition of multiple sensors to the quadrotor and applying algorithms to stabilize the quadrotor based on their measurements, and the Controller Design approach, which focuses on the development of an adaptive and robust controller. In this research, a learning controller is proposed as a solution for the issue of quadrotor trajectory control in confined environments. This controller utilizes Artificial Neural Networks to adjust for the unknown aerodynamics on-line. A systematic approach for controller design is developed, so that, the approach could be followed for the development of controllers for other nonlinear systems of similar form. One goal for this research is to develop a global controller that could be applied to any quadrotor with minimal adjustment. A novel Artificial Neural Network structure is presented that increases learning efficiency and speed. In addition, a new learning algorithm is developed for the Artificial Neural Network, when utilized with the developed controller.
Simulation results for the designed controller when applied to the Qball-X4 quadrotor are presented that show the effectiveness of the proposed Artificial Neural Network structure and the developed learning algorithm in the presence of variety of different unknown aerodynamics. These results are confirmed with real time experimentation, as the developed controller was successfully applied to Quanser’s Qball-X4 quadrotor for the flight control in confined environment. The practical challenges associated with the application of such a controller for quadrotor flight in confined environment are analyzed and adequately resolved to achieve an acceptable tracking performance.
Advisors/Committee Members: Thomas E. Alberts, Brett Newman, Drew Landman, Miltiadis Kotinis, Oscar R. González.
Subjects/Keywords: Artificial neural networks; Autonomous systems; Intelligent control; Nonlinear control; Robust control; UAV; Aerospace Engineering; Artificial Intelligence and Robotics; Robotics
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APA ·
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APA (6th Edition):
Mekky, A. (2018). Design and Implementation of an Artificial Neural Network Controller for Quadrotor Flight in Confined Environment. (Doctoral Dissertation). Old Dominion University. Retrieved from 9780355884210 ; https://digitalcommons.odu.edu/mae_etds/35
Chicago Manual of Style (16th Edition):
Mekky, Ahmed. “Design and Implementation of an Artificial Neural Network Controller for Quadrotor Flight in Confined Environment.” 2018. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9780355884210 ; https://digitalcommons.odu.edu/mae_etds/35.
MLA Handbook (7th Edition):
Mekky, Ahmed. “Design and Implementation of an Artificial Neural Network Controller for Quadrotor Flight in Confined Environment.” 2018. Web. 24 Jan 2021.
Vancouver:
Mekky A. Design and Implementation of an Artificial Neural Network Controller for Quadrotor Flight in Confined Environment. [Internet] [Doctoral dissertation]. Old Dominion University; 2018. [cited 2021 Jan 24].
Available from: 9780355884210 ; https://digitalcommons.odu.edu/mae_etds/35.
Council of Science Editors:
Mekky A. Design and Implementation of an Artificial Neural Network Controller for Quadrotor Flight in Confined Environment. [Doctoral Dissertation]. Old Dominion University; 2018. Available from: 9780355884210 ; https://digitalcommons.odu.edu/mae_etds/35
8.
Harrell, Joseph Vincent.
Theoretical Results Supporting the Use of Passive Damping as Augmentation to the Active Control of Flexible Structures.
Degree: PhD, Mechanical & Aerospace Engineering, 1993, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/230
► One challenge of modern control technology is how to control a flexible structure with accuracy, speed, and economy of effort. Controlling a structure with…
(more)
▼ One challenge of modern control technology is how to control a flexible structure with accuracy, speed, and economy of effort. Controlling a structure with many degrees of freedom by purely active means implies the implementation of inordinate sensors and actuators and creates the need for numerous calculations that must be done instantly. Experiments have shown that practical structures under active control alone can suffer instabilities due to modal vibrations beyond the bandwidth of the active controller. Furthermore, if there is a high degree of model uncertainty, instabilities can be produced by inputs of modal vibrations not occurring in the system model. The use of passive damping to stabilize those vibrations beyond the domain of the active controller and to help reduce the effects of model uncertainty has been shown to be critical to enabling control of flexible structures.
The question remains as to how passive damping should best be implemented to aid active control. The same amount of damping (by weight) can be applied in different ways – some ways may satisfy performance constraints, while others may not. Part I of this thesis deals with the effects of damping on control. The system to be controlled is defined by its linear matrix differential equation. The system is under the influence of a disturbance and a set of control forces. A performance index is defined, after which are derived closed-form expressions for the optimal feedback gains and the optimal value of the performance index. A modern passive damping technique is applied to a beam, and the cost function is optimized subject to the appropriate constraints. The benefits of the damping are demonstrated in the performance, the displacement output, and in the economic savings.
Part II of this thesis pursues the effects of passive damping on plant model reduction in modal coordinates. Prevailing closed-form expressions in this field assume light damping and widespread natural frequencies. A formula is derived based upon general constant-ratio damping and general spectrum of natural frequencies. Conclusions are drawn, and numerical examples demonstrate the effects of this new formula on model reduction as the modal damping ratio is varied.
Advisors/Committee Members: Thomas E. Alberts, Chuh Mei, G. McRee, Jen-Kuang Huang.
Subjects/Keywords: Control theory; Augmentation; Passive damping; Flexible structures; Mechanical Engineering; Structures and Materials; Systems Engineering and Multidisciplinary Design Optimization
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APA (6th Edition):
Harrell, J. V. (1993). Theoretical Results Supporting the Use of Passive Damping as Augmentation to the Active Control of Flexible Structures. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/230
Chicago Manual of Style (16th Edition):
Harrell, Joseph Vincent. “Theoretical Results Supporting the Use of Passive Damping as Augmentation to the Active Control of Flexible Structures.” 1993. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/230.
MLA Handbook (7th Edition):
Harrell, Joseph Vincent. “Theoretical Results Supporting the Use of Passive Damping as Augmentation to the Active Control of Flexible Structures.” 1993. Web. 24 Jan 2021.
Vancouver:
Harrell JV. Theoretical Results Supporting the Use of Passive Damping as Augmentation to the Active Control of Flexible Structures. [Internet] [Doctoral dissertation]. Old Dominion University; 1993. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/230.
Council of Science Editors:
Harrell JV. Theoretical Results Supporting the Use of Passive Damping as Augmentation to the Active Control of Flexible Structures. [Doctoral Dissertation]. Old Dominion University; 1993. Available from: https://digitalcommons.odu.edu/mae_etds/230
9.
Luo, Xiaobing.
Efficient Dynamic Unstructured Methods and Applications for Transonic Flows and Hypersonic Stage Separation.
Degree: PhD, Aerospace Engineering, 1999, Old Dominion University
URL: 9780599652736
;
https://digitalcommons.odu.edu/mae_etds/77
► Relative-moving boundary problems have a wide variety of applications. They appear in staging during a launch process, store separation from a military aircraft, rotor-stator…
(more)
▼ Relative-moving boundary problems have a wide variety of applications. They appear in staging during a launch process, store separation from a military aircraft, rotor-stator interaction in turbomachinery, and dynamic aeroelasticity.
The dynamic unstructured technology (DUT) is potentially a strong approach to simulate unsteady flows around relative-moving bodies, by solving time-dependent governing equations. The dual-time stepping scheme is implemented to improve its efficiency while not compromising the accuracy of solutions. The validation of the implicit scheme is performed on a pitching NACA0012 airfoil and a rectangular wing with low reduced frequencies in transonic flows. All the matured accelerating techniques, including the implicit residual smoothing, the local time stepping, and the Full-Approximate-Scheme (FAS) multigrid method, are resorted once a dynamic problem is transformed into a series of “static” problems. Even with rather coarse Euler-type meshes, one order of CPU time savings is achieved without losing the accuracy of solutions in comparison to the popular Runge-Kutta scheme. More orders of CPU time savings are expected in real engineering applications where highly stretched viscous-type meshes are needed.
The applicability of DUT is also extended from transonic/supersonic flows to hypersonic flows through special measures in spatial discretization to simulate the staging of a hypersonic vehicle.
First, the simulations in Mach 5 and Mach 10 flights are performed on the longitudinal symmetry plane. A network of strong shocks and expansion waves are captured. A prescribed two-degrees-of-freedom motion is imposed on the booster and the adapter to mimic the staging.
Then, a 3-D static Euler solver with an efficient edge-based data structure is modified for time-accurate flows. The overall history of aerodynamic interference during the staging in Mach 5 flight is obtained by an animation method, consisting of six static solutions along the assumed stage path. From the animation method, the following conclusions are made. After the booster and the adapter move away from the research vehicle by 60% vehicle length, their effects on the research vehicle are confined to the wake flow of the research vehicle. The aerodynamic forces on the research vehicle converge to the values in free flight when the booster is away from the research vehicle by 1.77 times vehicle length. The aerodynamic interference is a highly nonlinear function in terms of the distance between the vehicle, the booster, and the adapter.
Finally, two dynamic computations are performed when the booster and the adapter are extremely close to the research vehicle. It is observed from these 3-D dynamic computations that as the stage separation advances, the aerodynamic interference becomes less sensitive to further relative motions.
Advisors/Committee Members: Oktay Baysal, Thomas E. Alberts, Osama Kandil, David E. Reubush.
Subjects/Keywords: Dynamic unstructured; Hypersonic; Relative-moving boundary; Stage separation; Unsteady flows; Aerodynamics and Fluid Mechanics; Engineering Mechanics; Fluid Dynamics; Structures and Materials
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APA (6th Edition):
Luo, X. (1999). Efficient Dynamic Unstructured Methods and Applications for Transonic Flows and Hypersonic Stage Separation. (Doctoral Dissertation). Old Dominion University. Retrieved from 9780599652736 ; https://digitalcommons.odu.edu/mae_etds/77
Chicago Manual of Style (16th Edition):
Luo, Xiaobing. “Efficient Dynamic Unstructured Methods and Applications for Transonic Flows and Hypersonic Stage Separation.” 1999. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9780599652736 ; https://digitalcommons.odu.edu/mae_etds/77.
MLA Handbook (7th Edition):
Luo, Xiaobing. “Efficient Dynamic Unstructured Methods and Applications for Transonic Flows and Hypersonic Stage Separation.” 1999. Web. 24 Jan 2021.
Vancouver:
Luo X. Efficient Dynamic Unstructured Methods and Applications for Transonic Flows and Hypersonic Stage Separation. [Internet] [Doctoral dissertation]. Old Dominion University; 1999. [cited 2021 Jan 24].
Available from: 9780599652736 ; https://digitalcommons.odu.edu/mae_etds/77.
Council of Science Editors:
Luo X. Efficient Dynamic Unstructured Methods and Applications for Transonic Flows and Hypersonic Stage Separation. [Doctoral Dissertation]. Old Dominion University; 1999. Available from: 9780599652736 ; https://digitalcommons.odu.edu/mae_etds/77
10.
Xia, Houchun.
Fiber Enhanced Viscoelastic Damping Polymers and Their Application to Passive Vibration Control.
Degree: PhD, Mechanical & Aerospace Engineering, 1993, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/293
► A new composite damping material is investigated, which consists of a viscoelastic matrix and high elastic modulus fiber inclusions. This fiber enhanced viscoelastic damping…
(more)
▼ A new composite damping material is investigated, which consists of a viscoelastic matrix and high elastic modulus fiber inclusions. This fiber enhanced viscoelastic damping polymer is intended to be applied to light-weight flexible structures as surface treatment for passive vibration control. A desirable packing geometry for the composite material is proposed, which is expected to produce maximum shear strain in the viscoelastic damping matrix. Subsequently, a micromechanical model is established in which the effect of fiber segment length and relative motion between neighboring fibers are taken into account. Based on this model, closed form expressions for the effective storage and loss properties of the damping material are developed, and an optimal relation between design parameters, such as the length, diameter, spacing, and Young's modulus of fibers and the shear modulus of vicoelastic matrix, is derived for achieving a maximum damping capability. The theoretical development is validated by a NASTRAN finite element analysis. Upon comparison of an enhanced viscoelastic damping treatment with a conventionally constrained layer damping treatment, it is found that the enhanced polymer provides a significant improvement in damping abilities.
The proposed fiber enhanced viscoelastic damping polymer can be used either by itself as a passive damping measure for light-weight flexible structures or as an augmentation for active controllers to enhance control performance. Two examples are presented to demonstrate these two most important applications. The results show that the fiber enhanced damping polymer can provide significant damping to base structures at a broad frequency range and the performance of active controllers can be substantially improved by the addition of an optimally designed passive damping treatment. To allow comparison between theoretical and experimental analyses, dynamic scale testing techniques for structures with viscoelastic components are also examined.
Advisors/Committee Members: Thomas E. Alberts, Jen-Kuang Huang, Gene J.-W. Hou, Paul A. Coper.
Subjects/Keywords: Passive damping; Viscoelastic materials; Vibration; Composite; Mechanical Engineering; Polymer and Organic Materials; Structures and Materials
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APA (6th Edition):
Xia, H. (1993). Fiber Enhanced Viscoelastic Damping Polymers and Their Application to Passive Vibration Control. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/293
Chicago Manual of Style (16th Edition):
Xia, Houchun. “Fiber Enhanced Viscoelastic Damping Polymers and Their Application to Passive Vibration Control.” 1993. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/293.
MLA Handbook (7th Edition):
Xia, Houchun. “Fiber Enhanced Viscoelastic Damping Polymers and Their Application to Passive Vibration Control.” 1993. Web. 24 Jan 2021.
Vancouver:
Xia H. Fiber Enhanced Viscoelastic Damping Polymers and Their Application to Passive Vibration Control. [Internet] [Doctoral dissertation]. Old Dominion University; 1993. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/293.
Council of Science Editors:
Xia H. Fiber Enhanced Viscoelastic Damping Polymers and Their Application to Passive Vibration Control. [Doctoral Dissertation]. Old Dominion University; 1993. Available from: https://digitalcommons.odu.edu/mae_etds/293
11.
Bevan, Jeffrey S.
Piezoceramic Actuator Placement for Acoustic Control of Panels.
Degree: PhD, Mechanical & Aerospace Engineering, 2000, Old Dominion University
URL: 9780599965454
;
https://digitalcommons.odu.edu/mae_etds/179
► Optimum placement of multiple traditional piezoceramic actuators is determined for active structural acoustic control of flat panels. The structural acoustic response is determined using…
(more)
▼ Optimum placement of multiple traditional piezoceramic actuators is determined for active structural acoustic control of flat panels. The structural acoustic response is determined using acoustic radiation filters and structural surface vibration characteristics. Linear Quadratic Regulator (LQR) control is utilized to determine the optimum state feedback gain for active structural acoustic control. The optimum actuator location is determined by minimizing the structural acoustic radiated noise using a modified genetic algorithm. Experimental tests are conducted and compared to analytical results.
Anisotropic piezoceramic actuators exhibit enhanced performance when compared to traditional isotropic piezoceramic actuators. As a result of the inherent isotropy, these advanced actuators develop strain along the principal material axis. The orientation of anisotropic actuators is investigated on the effect of structural vibration and acoustic control of curved and flat panels. A fully coupled shallow shell finite element formulation is developed to include anisotropic piezoceramic actuators for shell structures.
Advisors/Committee Members: Chuh Mei, Thomas E. Alberts, Gary P. Gibbs, Donald L. Kunz, Brett A. Newman.
Subjects/Keywords: Acoustic; Actuator; Flat panels; Linear quadratic regulator; Piezoceramic; Acoustics, Dynamics, and Controls; Aerospace Engineering
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APA (6th Edition):
Bevan, J. S. (2000). Piezoceramic Actuator Placement for Acoustic Control of Panels. (Doctoral Dissertation). Old Dominion University. Retrieved from 9780599965454 ; https://digitalcommons.odu.edu/mae_etds/179
Chicago Manual of Style (16th Edition):
Bevan, Jeffrey S. “Piezoceramic Actuator Placement for Acoustic Control of Panels.” 2000. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9780599965454 ; https://digitalcommons.odu.edu/mae_etds/179.
MLA Handbook (7th Edition):
Bevan, Jeffrey S. “Piezoceramic Actuator Placement for Acoustic Control of Panels.” 2000. Web. 24 Jan 2021.
Vancouver:
Bevan JS. Piezoceramic Actuator Placement for Acoustic Control of Panels. [Internet] [Doctoral dissertation]. Old Dominion University; 2000. [cited 2021 Jan 24].
Available from: 9780599965454 ; https://digitalcommons.odu.edu/mae_etds/179.
Council of Science Editors:
Bevan JS. Piezoceramic Actuator Placement for Acoustic Control of Panels. [Doctoral Dissertation]. Old Dominion University; 2000. Available from: 9780599965454 ; https://digitalcommons.odu.edu/mae_etds/179
12.
Bloodgood, V. Dale, Jr.
Modeling Aspects of Magnetic Actuators and Magnetic Suspension Systems.
Degree: PhD, Mechanical & Aerospace Engineering, 2002, Old Dominion University
URL: 9780493712994
;
https://digitalcommons.odu.edu/mae_etds/216
► This dissertation is a study of new modeling techniques developed for magnetic suspension systems. The techniques discussed are modifications of magnetic circuit theory and…
(more)
▼ This dissertation is a study of new modeling techniques developed for magnetic suspension systems. The techniques discussed are modifications of magnetic circuit theory and fundamental eddy current models. The techniques are compared against experimental test results and finite element data. The information gained from the experimental testing is used to provide insight into magnetic bearing design.
A small-gap modeling technique called extended circuit theory is developed that incorporates information about the system gained from finite element data, or experimental data, to be included in the analytic model. The variations between the classical magnetic circuit model and the finite element model are used to develop performance coefficients, which are in turn incorporated into the extended circuit model. The coefficients modify the classical theory to account for magnetomotive force losses, flux leakage and flux fringing. The theory is developed from fundamental principles. The techniques used to determine, and predict, the coefficients are discussed. The use of this method in optimal bearing design is also discussed.
The extended circuit model is verified against experimental test results of a family of magnetic actuators. The actuators consist of a “C-shaped” stator and a flat armature. The pole separation distance was varied along with the location of the biasing permanent magnets and the windings. The permanent magnets were placed either on the pole faces, in the center of the armature, or at both locations, and the windings were wound on poles of the stator or on the back of the stator, resulting in a total of 22 design permutations. The experimental performance of each design is analyzed and efficiency trends are discussed.
The diffusive model for eddy currents is analyzed along with the lumped parameter model to explore the “half-order” behavior of eddy currents commonly observed in experimental testing. A fractional order eddy current model is developed and compared against finite element data and experimental test results. The models developed are based on a frequency dependent resistance. The implications of using fractional order modeling techniques, along with control considerations, are discussed.
Advisors/Committee Members: Colin P. Britcher, Thomas E. Alberts, Donald L. Kunz, W. Steven Gray, Nelson J. Groom.
Subjects/Keywords: Actuators; Eddy currents; Magnetic actuators; Magnetic suspension; Suspension; Mechanical Engineering; Structures and Materials
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APA (6th Edition):
Bloodgood, V. Dale, J. (2002). Modeling Aspects of Magnetic Actuators and Magnetic Suspension Systems. (Doctoral Dissertation). Old Dominion University. Retrieved from 9780493712994 ; https://digitalcommons.odu.edu/mae_etds/216
Chicago Manual of Style (16th Edition):
Bloodgood, V. Dale, Jr. “Modeling Aspects of Magnetic Actuators and Magnetic Suspension Systems.” 2002. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9780493712994 ; https://digitalcommons.odu.edu/mae_etds/216.
MLA Handbook (7th Edition):
Bloodgood, V. Dale, Jr. “Modeling Aspects of Magnetic Actuators and Magnetic Suspension Systems.” 2002. Web. 24 Jan 2021.
Vancouver:
Bloodgood, V. Dale J. Modeling Aspects of Magnetic Actuators and Magnetic Suspension Systems. [Internet] [Doctoral dissertation]. Old Dominion University; 2002. [cited 2021 Jan 24].
Available from: 9780493712994 ; https://digitalcommons.odu.edu/mae_etds/216.
Council of Science Editors:
Bloodgood, V. Dale J. Modeling Aspects of Magnetic Actuators and Magnetic Suspension Systems. [Doctoral Dissertation]. Old Dominion University; 2002. Available from: 9780493712994 ; https://digitalcommons.odu.edu/mae_etds/216
13.
Kelkar, Atul G.
Robust Control of Nonlinear Multibody Flexible Space Structures.
Degree: PhD, Mechanical & Aerospace Engineering, 1993, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/244
► A generic nonlinear math model of a multibody flexible system is developed. Asymptotic stability of such systems using dissipative compensators is established. It is…
(more)
▼ A generic nonlinear math model of a multibody flexible system is developed. Asymptotic stability of such systems using dissipative compensators is established. It is proved that, under certain conditions, this class of systems exhibit global asymptotic stability under dissipative compensation. The dissipative compensators considered are static as well as dynamic dissipative compensators. The stability proofs are based on passivity approaches, Lyapunov methods, as well as a key property of such systems, i.
e., skew-symmetricity of certain matrix. The importance of the stability results obtained is that the stability is robust to parametric uncertainties and modeling errors.
For static dissipative compensators, it is shown that stability is not only robust to parametric uncertainties and modeling errors but also to certain actuator and sensor nonlinearities. Actuator nonlinearities considered are (0, ∞) sector monotonically non-decreasing type, which include realistic nonlinearities such as the saturation nonlinearity. In the presence of dead-zone and hysteresis type nonlinearities, system trajectories do not approach equilibrium point asymptotically, however, it is shown that there is a compact region of ultimate boundedness and system trajectories do not go unbounded. The sensor nonlinearities considered are (0,∞) sector nonlinearities.
A more versatile class of dissipative compensators, called dynamic dissipative compensators, is next considered. A control designer has more design freedom with dynamic dissipative compensators than with the static dissipative type. The increased design degrees of freedom can be used to enhance the performance of the control system.
The synthesis techniques for static as well as dynamic dissipative compensators for multibody, nonlinear, flexible systems are currently unknown and it is a topic of future research. The asymptotic stability property of a static dissipative controller for multibody, nonlinear, flexible space structures is demonstrated through a simulation example. The example system used consists of a flexible 10-bay truss structure with a flexible, 2-link manipulator arm attached at one end of the truss. This example system is representative of the class of spacecraft envisioned for the future missions. For dynamic dissipative compensators an application example is shown for a multibody planar system with an articulated member. The controller design is based on locally linearized models in the configuration space of the articulated member. This example also demonstrates the use of dissipative compensators in the integrated design framework.
Advisors/Committee Members: Thomas E. Alberts, Suresh M. Joshi, Gene Hou, Oscar R. Gonzalez, Jen K. Huang.
Subjects/Keywords: Asymptotic stability; Multibody flexible system; Static dissipative compensators; Nonlinear; Mechanical Engineering; Structures and Materials
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APA (6th Edition):
Kelkar, A. G. (1993). Robust Control of Nonlinear Multibody Flexible Space Structures. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/244
Chicago Manual of Style (16th Edition):
Kelkar, Atul G. “Robust Control of Nonlinear Multibody Flexible Space Structures.” 1993. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/244.
MLA Handbook (7th Edition):
Kelkar, Atul G. “Robust Control of Nonlinear Multibody Flexible Space Structures.” 1993. Web. 24 Jan 2021.
Vancouver:
Kelkar AG. Robust Control of Nonlinear Multibody Flexible Space Structures. [Internet] [Doctoral dissertation]. Old Dominion University; 1993. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/244.
Council of Science Editors:
Kelkar AG. Robust Control of Nonlinear Multibody Flexible Space Structures. [Doctoral Dissertation]. Old Dominion University; 1993. Available from: https://digitalcommons.odu.edu/mae_etds/244
14.
Locke, James Eugene.
A Finite Element Formulation for the Large Deflection Random Response of Thermally Buckled Structures.
Degree: PhD, Mechanical & Aerospace Engineering, 1988, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/257
► The effects of temperature and acoustic loading are included in a theoretical finite element large deflection formulation for thin, isotropic plate and beam type…
(more)
▼ The effects of temperature and acoustic loading are included in a theoretical finite element large deflection formulation for thin, isotropic plate and beam type structures. Thermal loads are applied as steady-state temperature distributions, and acoustic loads are taken to be stationary and Gaussian with zero mean and uniform magnitude and phase over the surface of the structure. Material properties are considered to be independent of temperature. Also, inplane and rotary inertia terms are assumed to be neglegible, and all inplane edge conditions are taken to be immovable. For the random vibration analysis, cross correlation terms are included.
The nature of the loads leads to the solution of two separate problems. First, the problem of thermal postbuckling is solved to determine the deflections and stresses due to the thermal load only. These deflections and stresses are then used as initial deflections and stresses for the random vibration analysis.
Since both analyses are nonlinear, iterative techniques are used to solve each. The solution technique used for the thermal postbuckling analysis is that of Newton-Raphson iteration. This method is found to always converge; whereas, direct iteration fails to converge. For the large deflection random vibration analysis, the linear mode shapes of the thermally buckled structure are used to reduce the equations of motion to a system of nonlinear modal equations. An equivalent linearization technique is then used to iteratively solve for the mean square deflections. Instead of using direct iteration, an underrelaxation technique is employed to reduce the number of iterations required for a converged solution. In addition to obtaining mean square deflections, the boundary for stable random vibrations for the thermally buckled structure (snap-through boundary) is predicted by considering the incremental equations of motion.
Solutions obtained using these analysis methods are compared with previous solutions to assess the accuracy of the finite element formulation. The thermal postbuckling solution is compared with a 25-mode classical solution for a square plate clamped on all edges, and the random vibration solution is compared with 100-mode classical beam solutions.
The present study shows that the infinite element method can be used to analyze structures subjected to combined thermal-acoustic loads.
Advisors/Committee Members: Chuh Mei, John S. Mixson, Thomas E. Alberts, Gene Hou, J. M. Dorrepaal.
Subjects/Keywords: Acoustic loading; Temperature; Buckled structures; Finite element; Applied Mechanics; Structures and Materials
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APA (6th Edition):
Locke, J. E. (1988). A Finite Element Formulation for the Large Deflection Random Response of Thermally Buckled Structures. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/257
Chicago Manual of Style (16th Edition):
Locke, James Eugene. “A Finite Element Formulation for the Large Deflection Random Response of Thermally Buckled Structures.” 1988. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/257.
MLA Handbook (7th Edition):
Locke, James Eugene. “A Finite Element Formulation for the Large Deflection Random Response of Thermally Buckled Structures.” 1988. Web. 24 Jan 2021.
Vancouver:
Locke JE. A Finite Element Formulation for the Large Deflection Random Response of Thermally Buckled Structures. [Internet] [Doctoral dissertation]. Old Dominion University; 1988. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/257.
Council of Science Editors:
Locke JE. A Finite Element Formulation for the Large Deflection Random Response of Thermally Buckled Structures. [Doctoral Dissertation]. Old Dominion University; 1988. Available from: https://digitalcommons.odu.edu/mae_etds/257
15.
Kassem, Ayman Hamdy.
Approximate Analytical Relationships for Linear Optimal Aeroelastic Flight Control Laws.
Degree: PhD, Aerospace Engineering, 1998, Old Dominion University
URL: 9780599059542
;
https://digitalcommons.odu.edu/mae_etds/63
► This dissertation introduces new methods to uncover functional relationships between design parameters of a contemporary control design technique and the resulting closed-loop properties. Three…
(more)
▼ This dissertation introduces new methods to uncover functional relationships between design parameters of a contemporary control design technique and the resulting closed-loop properties. Three new methods are developed for generating such relationships through analytical expressions: the Direct Eigen-Based Technique, the Order of Magnitude Technique, and the Cost Function Imbedding Technique. Efforts concentrated on the linear-quadratic state-feedback control-design technique applied to an aeroelastic flight control task. For this specific application, simple and accurate analytical expressions for the closed-loop eigenvalues and zeros in terms of basic parameters such as stability and control derivatives, structural vibration damping and natural frequency, and cost function weights are generated. These expressions explicitly indicate how the weights augment the short period and aeroelastic modes, as well as the closed-loop zeros, and by what physical mechanism. The analytical expressions are used to address topics such as damping, nonminimum phase behavior, stability, and performance with robustness considerations, and design modifications. This type of knowledge is invaluable to the flight control designer and would be more difficult to formulate when obtained from numerical-based sensitivity analysis.
Advisors/Committee Members: Brett A. Newman, Colin P. Britcher, Thomas E. Alberts, Jen K. Huang.
Subjects/Keywords: Aeroelastic; Flight control; Aerospace Engineering
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APA (6th Edition):
Kassem, A. H. (1998). Approximate Analytical Relationships for Linear Optimal Aeroelastic Flight Control Laws. (Doctoral Dissertation). Old Dominion University. Retrieved from 9780599059542 ; https://digitalcommons.odu.edu/mae_etds/63
Chicago Manual of Style (16th Edition):
Kassem, Ayman Hamdy. “Approximate Analytical Relationships for Linear Optimal Aeroelastic Flight Control Laws.” 1998. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9780599059542 ; https://digitalcommons.odu.edu/mae_etds/63.
MLA Handbook (7th Edition):
Kassem, Ayman Hamdy. “Approximate Analytical Relationships for Linear Optimal Aeroelastic Flight Control Laws.” 1998. Web. 24 Jan 2021.
Vancouver:
Kassem AH. Approximate Analytical Relationships for Linear Optimal Aeroelastic Flight Control Laws. [Internet] [Doctoral dissertation]. Old Dominion University; 1998. [cited 2021 Jan 24].
Available from: 9780599059542 ; https://digitalcommons.odu.edu/mae_etds/63.
Council of Science Editors:
Kassem AH. Approximate Analytical Relationships for Linear Optimal Aeroelastic Flight Control Laws. [Doctoral Dissertation]. Old Dominion University; 1998. Available from: 9780599059542 ; https://digitalcommons.odu.edu/mae_etds/63
16.
Omran, Ashraf Mohammed Kandeel.
Solution Approximation for Atmospheric Flight Dynamics Using Volterra Theory.
Degree: PhD, Aerospace Engineering, 2010, Old Dominion University
URL: 9781124504261
;
https://digitalcommons.odu.edu/mae_etds/81
► This dissertation introduces a set of novel approaches in order to facilitate and enrich Volterra theory as a nonlinear approximation technique for constructing mathematical…
(more)
▼ This dissertation introduces a set of novel approaches in order to facilitate and enrich Volterra theory as a nonlinear approximation technique for constructing mathematical solutions from the governing relationships describing aircraft dynamic behavior. These approaches reconnect Volterra theory and flight mechanics research, which has not been addressed in the technical literature for over twenty years. Volterra theory is known to be viable in modeling weak nonlinearities, but is not particularly well suited for directly describing high performance aircraft dynamics. In order to overcome these obstacles and restrictions of Volterra theory, the global Piecewise Volterra Approach has been developed. This new approach decomposes a strong nonlinearity into weaker components in several sub-regions, which individually only require a low order truncated series. A novel Cause-and-Effect Analysis of these low order truncated series has also been developed. This new technique in turn allows system prediction before employing computer simulation, as well as decomposition of existing simulation results. For a computationally complex and large envelope airframe system, a Volterra Parameter-Varying Model Approach has also been developed as a systematically efficient approach to track the aircraft dynamic model and its response across a wide range of operating conditions. The analytical and numerical solutions based on the proposed methodology show the ability of Volterra theory to help predict, understand, and analyze nonlinear aircraft behavior beyond that attainable by linear theory, or more difficult to extract from nonlinear simulation, which in turn leads to a more efficient nonlinear preliminary design tool.
Advisors/Committee Members: Brett A. Newman, Thomas E. Alberts, Colin P. Britcher, Zhao Sun.
Subjects/Keywords: Aircraft; Flight performance; Volterra theory; Aerospace Engineering
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APA (6th Edition):
Omran, A. M. K. (2010). Solution Approximation for Atmospheric Flight Dynamics Using Volterra Theory. (Doctoral Dissertation). Old Dominion University. Retrieved from 9781124504261 ; https://digitalcommons.odu.edu/mae_etds/81
Chicago Manual of Style (16th Edition):
Omran, Ashraf Mohammed Kandeel. “Solution Approximation for Atmospheric Flight Dynamics Using Volterra Theory.” 2010. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9781124504261 ; https://digitalcommons.odu.edu/mae_etds/81.
MLA Handbook (7th Edition):
Omran, Ashraf Mohammed Kandeel. “Solution Approximation for Atmospheric Flight Dynamics Using Volterra Theory.” 2010. Web. 24 Jan 2021.
Vancouver:
Omran AMK. Solution Approximation for Atmospheric Flight Dynamics Using Volterra Theory. [Internet] [Doctoral dissertation]. Old Dominion University; 2010. [cited 2021 Jan 24].
Available from: 9781124504261 ; https://digitalcommons.odu.edu/mae_etds/81.
Council of Science Editors:
Omran AMK. Solution Approximation for Atmospheric Flight Dynamics Using Volterra Theory. [Doctoral Dissertation]. Old Dominion University; 2010. Available from: 9781124504261 ; https://digitalcommons.odu.edu/mae_etds/81
17.
Oleszczuk, Grzegorz.
Robustness and Control of a Magnetically Levitated Transportation System.
Degree: PhD, Aerospace Engineering, 2006, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/82
► Electromagnetic suspension of Magnetic Levitation Vehicles (Maglev) has been studied for many years as an alternative to wheel-on rail transportation systems. In this work,…
(more)
▼ Electromagnetic suspension of Magnetic Levitation Vehicles (Maglev) has been studied for many years as an alternative to wheel-on rail transportation systems. In this work, design and implementation of control systems for a Maglev laboratory experiment and a Maglev vehicle under development at
Old Dominion University are described. Both plants are modeled and simulated with consideration of issues associated with system non-linearity, structural flexibility and electromagnetic force modeling. Discussion concerning different control strategies, namely centralized and decentralized approaches are compared and contrasted in this work. Different types of electromagnetic non-linearities are considered and described to establish a convenient method for modeling such a system. It is shown how a Finite Element structural model can be incorporated into the system to obtain transfer function notation. Influence of the dynamic interaction between the Maglev track and the Maglev vehicle is discussed and supported by both analytical results and theoretical examples. Finally, several control laws designed to obtain stable and robust levitation are explored in detail.
Advisors/Committee Members: Thomas E. Alberts, Colin P. Britcher, Jeremiah F. Creedon, Oscar R. Gonzalez, Brett A. Newman.
Subjects/Keywords: Maglev vehicles; Magnetically levitated; Transportation; Aerospace Engineering; Electromagnetics and Photonics; Mechanical Engineering; Transportation
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APA (6th Edition):
Oleszczuk, G. (2006). Robustness and Control of a Magnetically Levitated Transportation System. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/82
Chicago Manual of Style (16th Edition):
Oleszczuk, Grzegorz. “Robustness and Control of a Magnetically Levitated Transportation System.” 2006. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/82.
MLA Handbook (7th Edition):
Oleszczuk, Grzegorz. “Robustness and Control of a Magnetically Levitated Transportation System.” 2006. Web. 24 Jan 2021.
Vancouver:
Oleszczuk G. Robustness and Control of a Magnetically Levitated Transportation System. [Internet] [Doctoral dissertation]. Old Dominion University; 2006. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/82.
Council of Science Editors:
Oleszczuk G. Robustness and Control of a Magnetically Levitated Transportation System. [Doctoral Dissertation]. Old Dominion University; 2006. Available from: https://digitalcommons.odu.edu/mae_etds/82
18.
Schultz, Karl Ulrich.
Development of a Nonlinear Estimator-Based Model of Pilot Performance During Brownout Conditions.
Degree: PhD, Aerospace Engineering, 2006, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/88
► During conditions of visual occlusion, pilots are forced to rapidly adapt their scan to accommodate the new observable states via instruments rather than the…
(more)
▼ During conditions of visual occlusion, pilots are forced to rapidly adapt their scan to accommodate the new observable states via instruments rather than the visual environment. During this transition, the provision of aircraft state information via other than visual modalities improves pilot performance presumably through the increase in situational awareness provided immediately following the visual occlusion event.
The Tactile Situational Awareness System (TSAS) was developed to provide continuous position information to the pilot via tactile rather than visual means. However, as a low-resolution display, significant preprocessing of information is required to maximize utility of this new technology.
Development of a nonlinear time varying estimator based multivariable model enables more accurate reproduction of pilot performance than previous models and provides explanations of many observed phenomena. The use of LQR feedback and an optimal estimator is heuristically consistent with reported strategies and was able to match pilot incorporation of multi-modal displays. Development of a nonlinear stochastic map of pilot "move-and-hold" control performance was able to accurately match increased pilot control noise at higher frequencies, a phenomenon formerly attributed to closed loop neuromuscular effects. The continued improvement of this model could eventually result in the early stage mathematical prediction of the effectiveness of emerging cockpit technology and preprocessing algorithms, prior to costly hardware development and flight evaluation.
Advisors/Committee Members: Thomas E. Alberts, Brett Newman, Colin P. Britcher, Braden J. McGrath.
Subjects/Keywords: Brownout; Pilot performance; Tactile situational awareness system; Visual occlusion; Aerospace Engineering
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APA (6th Edition):
Schultz, K. U. (2006). Development of a Nonlinear Estimator-Based Model of Pilot Performance During Brownout Conditions. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/88
Chicago Manual of Style (16th Edition):
Schultz, Karl Ulrich. “Development of a Nonlinear Estimator-Based Model of Pilot Performance During Brownout Conditions.” 2006. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/88.
MLA Handbook (7th Edition):
Schultz, Karl Ulrich. “Development of a Nonlinear Estimator-Based Model of Pilot Performance During Brownout Conditions.” 2006. Web. 24 Jan 2021.
Vancouver:
Schultz KU. Development of a Nonlinear Estimator-Based Model of Pilot Performance During Brownout Conditions. [Internet] [Doctoral dissertation]. Old Dominion University; 2006. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/88.
Council of Science Editors:
Schultz KU. Development of a Nonlinear Estimator-Based Model of Pilot Performance During Brownout Conditions. [Doctoral Dissertation]. Old Dominion University; 2006. Available from: https://digitalcommons.odu.edu/mae_etds/88
19.
Yu, Si-bok.
Life-Extending Control for a Highly Maneuverable Flight Vehicle.
Degree: PhD, Aerospace Engineering, 2003, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/95
► This dissertation investigates the feasibility and potential of life extension control logic for reducing fatigue within aerospace vehicle structural components. A key underpinning of…
(more)
▼ This dissertation investigates the feasibility and potential of life extension control logic for reducing fatigue within aerospace vehicle structural components. A key underpinning of this control logic is to exploit nonintuitive, optimal loading conditions which minimize nonlinear crack growth behavior, as predicted by analytical fatigue models with experimentally validated behavior. A major simplification in the development of life extension control logic is the observation and justification that optimal stress loading conditions, as described by overload magnitude ratio and application interval, are primarily independent of crack length and therefore, component age. This weak relationship between optimal stress loading and structural age implies the life extension control logic does not require tight integration with real-time health monitoring systems performing crack state estimation from measurement and model simulation. At a fundamental level, the life extension control logic conducts load alleviation and/or amplification tailoring of external and internal excitations to optimally exploit nonlinear crack retardation phenomenon. The life extension control logic is designed to be a simple, practical modification applied to an existing flight control system. A nonlinear autopilot for the nonlinear F-16 dynamics, coupled with a separate flexible F-16 wing model and a state space crack growth model, are used to demonstrate the life extension control concept. Results indicate that significant structural life savings is obtained by integrating life extending control logic dedicated for critical structural components to the existing flight control system. On the other hand, some components under life extending control showed minor reductions of structural life, particularly when the components are located in a low stress region where fatigue damage is of lower concern. Further, to achieve enhanced long-term structural integrity with life extending control, tradeoffs with flight system stability and performance may be required. Careful consideration is thus necessary when applying life extending logic to the aircraft flight control system. Although life extending control appears feasible with significant potential, full implementation of the concept requires further study.
Advisors/Committee Members: Brett A. Newman, Chuh Mei, Jen-Kuang Huang, Thomas E. Alberts.
Subjects/Keywords: Aircraft; Fatigue crack; Flight vehicle; Maneuverable; Aerospace Engineering
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APA (6th Edition):
Yu, S. (2003). Life-Extending Control for a Highly Maneuverable Flight Vehicle. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/95
Chicago Manual of Style (16th Edition):
Yu, Si-bok. “Life-Extending Control for a Highly Maneuverable Flight Vehicle.” 2003. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/95.
MLA Handbook (7th Edition):
Yu, Si-bok. “Life-Extending Control for a Highly Maneuverable Flight Vehicle.” 2003. Web. 24 Jan 2021.
Vancouver:
Yu S. Life-Extending Control for a Highly Maneuverable Flight Vehicle. [Internet] [Doctoral dissertation]. Old Dominion University; 2003. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/95.
Council of Science Editors:
Yu S. Life-Extending Control for a Highly Maneuverable Flight Vehicle. [Doctoral Dissertation]. Old Dominion University; 2003. Available from: https://digitalcommons.odu.edu/mae_etds/95
20.
Zhu, Xuegeng.
Placement of Piezoelectric Actuators for Active Control of Vibration Using Modal Parameters.
Degree: PhD, Aerospace Engineering, 1998, Old Dominion University
URL: 9780599208902
;
https://digitalcommons.odu.edu/mae_etds/97
► An equation is derived to model the piezoelectric actuators incorporation with flexible structures. This equation permits the comparison of the performance indices over the…
(more)
▼ An equation is derived to model the piezoelectric actuators incorporation with flexible structures. This equation permits the comparison of the performance indices over the entire structure for a piezoelectric actuator with constant area, which is unachievable if the Finite Element Method is used for complicated structures.
An index has been developed for placement of piezoelectric actuator for control of vibration of a flexible structure. This index is derived from the definition of
H2norm. Computation of the proposed index requires only the natural frequencies and corresponding mode shapes of the structures of interest. The method is well suited to large structure application because of the simplicity of the calculation. The proposed index is valid either for point sensor and actuator or for distributed types such as piezoelectric. Application of the method for different combinations of sensors and actuators has been discussed. Both piezoelectric patch and piezoelectric fiber actuators are used to verify the effectiveness of the proposed index.
The comparison of
H2 and
H ∞ norms shows good agreement for beam and plate models with single, three, and six modes. The comparison of
H2 and
H∞ norms is also made for a cantilevered beam with fixed sensor location, and a simply supported plate with a piezoelectric fiber actuator. Agreement between those two norms as well as the proposed index is demonstrated through all the cases.
Imbedded piezoelectric fiber actuators, which, are able to supply anisotropic control actuation, have an optimal fiber orientation, which is related to different structures, but independent of the volume fraction of the PZT fibers. Piezoelectric fiber actuator with volume fraction ν
f < 1 creates twisting moment, which has better performance than that of a monolithic piezoelectric patch actuator in control of twisting mode.
Advisors/Committee Members: Thomas E. Alberts, Chuh Mei, Jeng-Jong Ro, Jen-Kuang Huang.
Subjects/Keywords: Active control; Modal parameters; Piezoelectric actuators; Vibration; Aerospace Engineering; Engineering Mechanics; Mechanical Engineering; Structures and Materials
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APA (6th Edition):
Zhu, X. (1998). Placement of Piezoelectric Actuators for Active Control of Vibration Using Modal Parameters. (Doctoral Dissertation). Old Dominion University. Retrieved from 9780599208902 ; https://digitalcommons.odu.edu/mae_etds/97
Chicago Manual of Style (16th Edition):
Zhu, Xuegeng. “Placement of Piezoelectric Actuators for Active Control of Vibration Using Modal Parameters.” 1998. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
9780599208902 ; https://digitalcommons.odu.edu/mae_etds/97.
MLA Handbook (7th Edition):
Zhu, Xuegeng. “Placement of Piezoelectric Actuators for Active Control of Vibration Using Modal Parameters.” 1998. Web. 24 Jan 2021.
Vancouver:
Zhu X. Placement of Piezoelectric Actuators for Active Control of Vibration Using Modal Parameters. [Internet] [Doctoral dissertation]. Old Dominion University; 1998. [cited 2021 Jan 24].
Available from: 9780599208902 ; https://digitalcommons.odu.edu/mae_etds/97.
Council of Science Editors:
Zhu X. Placement of Piezoelectric Actuators for Active Control of Vibration Using Modal Parameters. [Doctoral Dissertation]. Old Dominion University; 1998. Available from: 9780599208902 ; https://digitalcommons.odu.edu/mae_etds/97
21.
Xue, David Yongxiang.
Finite Element Frequency Domain Solution of Nonlinear Panel Flutter With Temperature Effects and Fatigue Life Analysis.
Degree: PhD, Mechanical & Aerospace Engineering, 1991, Old Dominion University
URL: https://digitalcommons.odu.edu/mae_etds/294
► A frequency domain solution method for nonlinear panel flutter with thermal effects using a consistent finite element formulation has been developed. The von Karman…
(more)
▼ A frequency domain solution method for nonlinear panel flutter with thermal effects using a consistent finite element formulation has been developed. The von Karman nonlinear strain-displacement relation is used to account for large deflections, the quasi-steady first-order piston theory is employed for aerodynamic loading and the quasi-steady thermal stress theory is applied for the thermal stresses with a given change of the temperature distribution, ΔΤ (x, y, z). The equation of motion under a combined thermal-aerodynamic loading can be mathematically separated into two equations and then solved in sequence: (1) thermal-aerodynamic postbuckling and (2) limit-cycle oscillation. The Newton-Raphson iteration technique is used to solve the nonlinear algebraic equations and an updated linearized eigen-solution procedure is adopted to solve the nonlinear differential equations. The finite-element frequency domain solution results are compared with numerical time integration results. Limit-cycle responses, flutter boundaries, snap-through areas and stress distributions are obtained from the present analyses. The effects of different temperature distributions, panel aspect ratios and boundary support conditions are investigated.
The influence of temperature and dynamic pressure on panel fatigue life is also presented. The relation of dynamic pressure versus panel life time at a given temperature is established and an endurance and failure dynamic pressures on panel fatigue life can be estimated.
Advisors/Committee Members: Chuh Mei, Gene J.-W. Hou, Thomas E. Alberts, Duc T. Nguyen, Ptamote Dechaumphai, Charles P. Shore.
Subjects/Keywords: Flutter; Aeroelasticity; Finite element; Temperature; Fatigue; Applied Mechanics; Engineering Mechanics; Structures and Materials
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APA ·
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MLA ·
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Export
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Manager
APA (6th Edition):
Xue, D. Y. (1991). Finite Element Frequency Domain Solution of Nonlinear Panel Flutter With Temperature Effects and Fatigue Life Analysis. (Doctoral Dissertation). Old Dominion University. Retrieved from https://digitalcommons.odu.edu/mae_etds/294
Chicago Manual of Style (16th Edition):
Xue, David Yongxiang. “Finite Element Frequency Domain Solution of Nonlinear Panel Flutter With Temperature Effects and Fatigue Life Analysis.” 1991. Doctoral Dissertation, Old Dominion University. Accessed January 24, 2021.
https://digitalcommons.odu.edu/mae_etds/294.
MLA Handbook (7th Edition):
Xue, David Yongxiang. “Finite Element Frequency Domain Solution of Nonlinear Panel Flutter With Temperature Effects and Fatigue Life Analysis.” 1991. Web. 24 Jan 2021.
Vancouver:
Xue DY. Finite Element Frequency Domain Solution of Nonlinear Panel Flutter With Temperature Effects and Fatigue Life Analysis. [Internet] [Doctoral dissertation]. Old Dominion University; 1991. [cited 2021 Jan 24].
Available from: https://digitalcommons.odu.edu/mae_etds/294.
Council of Science Editors:
Xue DY. Finite Element Frequency Domain Solution of Nonlinear Panel Flutter With Temperature Effects and Fatigue Life Analysis. [Doctoral Dissertation]. Old Dominion University; 1991. Available from: https://digitalcommons.odu.edu/mae_etds/294
. 
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