Modeling Analysis and Control of Nonlinear Aeroelastic Systems

Airplane wings, turbine blades and other structures subjected to air or water flows, can undergo motions depending on their flexibility. As such, the performance of these systems depends strongly on their geometry and material properties. Of particular importance is the contribution of different nonlinear aspects. These aspects can be of two types: aerodynamic and structural. Examples of aerodynamic aspects include but are not lomited to flow separation and wake effects. Examples of structural aspects include but not limited to large deformations (geometric nonlinearities), concentrated masses or elements (inertial nonlinearities) and freeplay. In some systems, and depending on the parameters, the nonlinearities can cause multiple solutions. Determining the effects of nonlinearities of an aeroelastic system on its response is crucial. In this dissertation, different aeroelastic configurations where nonlinear aspects may have significant effects on their performance are considered. These configurations include: the effects of the wake on the flutter speed of a wing placed under different angles of attack, the impacts of the wing rotation as well as the aerodynamic and structural nonlinearities on the flutter speed of a rotating blade, and the effects of the recently proposed nonlinear energy sink on the flutter and ensuing limit cycle oscillations of airfoils and wings. For the modeling and analysis of these systems, we use models with different levels of fidelity as required to achieve the stated goals. We also use nonlinear dynamic analysis tools such as the normal form to determine specific effects of nonlinearities on the type of instability.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Science and Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2015

Author dc:creator

• Bichiou, Youssef

Chair dc:contributor.committeechair

• Hajj, Muhammad R.

Committee members dc:contributor.committeemember

• Ragab, Saad A.
• De Vita, Raffaella
• Patil, Mayuresh J.
• Al-Haik, Marwan

• Nonlinear Dynamics
• Normal Form
• Hopf Bifurcation
• Unsteady Aerodynamics
• Quasi-steady Aerodynamics
• Unsteady Vortex Lattice Method
• Control
• Wind Energy
• Wind Turbine Blades

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:3997

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/71760