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Active Control of Nonlinear Aeroelasticity / JAMES ELLIS
Swansea University Author: JAMES ELLIS
DOI (Published version): 10.23889/SUThesis.69939
Abstract
Aeroelasticity is the study of how aerodynamic, elastic, and inertial forces interact with each other and influence the static and dynamic response of structures. By utilising computer simulation and wind tunnel testing, the dynamic responses of an aeroelastic system can be determined for a range of...
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Swansea University, Wales, UK
2025
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Jiffri, S., and Friswell, M. I. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa69939 |
| Abstract: |
Aeroelasticity is the study of how aerodynamic, elastic, and inertial forces interact with each other and influence the static and dynamic response of structures. By utilising computer simulation and wind tunnel testing, the dynamic responses of an aeroelastic system can be determined for a range of airspeeds and combinations of system parameters, for both structurally linear and nonlinear configurations. The inclusion of one or more control surfaces enables the exploration of a variety of control methods that may be tailored to achieve a desired outcome, and could also potentially introduce additional dynamic phenomena arising from the control surface. The application of linear and nonlinear active control methods to mitigate vibrations is explored, both in the presence of gusts and to extend the flutter speed for a given system. The effects of gusts, both uncontrolled and controlled, on the dynamic behaviour of the system are also investigated. The approach used in meeting the above aims includes simulating aeroelastic response of a numerical model of various configurations of a flexible fixed-wing rig equipped with two control surfaces (suitable for wind tunnel mounting and testing), already available for use. The model in question is then used to investigate the Receptance Method for gust response alleviation, with numerical results showing a significant reduction in wing deflection due to gusts, with oscillations returning to rest within 3 seconds following a gust encounter. Then, the design of an updated version of the available wing that is better suited to the Swansea University test conditions is used to again employ the Receptance Method, but with the aim of extending the flutter speed. Numerical results show that a 22%increase to the flutter speed could be achieved using this method. Experimental tests demonstrated the importance of the position of natural frequencies for different modes as coupled motion prevents the acquisition of receptance data. Numerically, a nonlinearity is designed and implemented, and feedback linearisation is carried out on the system, with results showing reduction in vibration by counteracting flutter following perturbation due to gusts, resulting in a stable system. Finally, a new wing model capable of using a fixed, passive folding, and active folding wing tips is used in the wind tunnel to analyse the wing root bending moment in the presence of gusts. The active control law used is PD control, which results in up to a 29.3% reduction in bending moment due to gusts for some experimental cases. The outcome is that this project investigated some novel methods for active control of aeroelastic systems, which are also effective in situations where gust inputs are significant. Such an increase in the ability to control the dynamics of aeroelastic systems in the presence of nonlinearities and gust inputs –both of which are very real phenomena in the real world – could translate to practical benefits such as longevity of aircraft, increased passenger comfort, not requiring overly conservative safety factors in the design process etc, ultimately resulting in significant cost savings and greener engineering. The control methods used in this work have shown promise and should be used for environmentally friendly future aircraft designs.Then, the design of an updated version of the available wing that is better suited to the Swansea University test conditions is used to again employ the Receptance Method, but with the aim of extending the flutter speed. Numerical results show that a 22%increase to the flutter speed could be achieved using this method. Experimental tests demonstrated the importance of the position of natural frequencies for different modes as coupled motion prevents the acquisition of receptance data. Numerically, a nonlinearity is designed and implemented, and feedback linearisation is carried out on the system, with results showing reduction in vibration by counteracting flutter following perturbation due to gusts, resulting in a stable system. Finally, a new wing model capable of using a fixed, passive folding, and active folding wing tips is used in the wind tunnel to analyse the wing root bending moment in the presence of gusts. The active control law used is PD control, which results in up to a 29.3% reduction in bending moment due to gusts for some experimental cases. The outcome is that this project investigated some novel methods for active control of aeroelastic systems, which are also effective in situations where gust inputs are significant. Such an increase in the ability to control the dynamics of aeroelastic systems in the presence of nonlinearities and gust inputs –both of which are very real phenomena in the real world – could translate to practical benefits such as longevity of aircraft, increased passenger comfort, not requiring overly conservative safety factors in the design process etc, ultimately resulting in significant cost savings and greener engineering. The control methods used in this work have shown promise and should be used for environmentally friendly future aircraft designs. |
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| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. |
| Keywords: |
Aeroelasticity, Active Control, Nonlinearity |
| College: |
Faculty of Science and Engineering |
| Funders: |
EPSRC doctoral training grant |