Title page for ETD etd-91498-143821


Type of Document Dissertation
Author Preidikman, Sergio
Author's Email Address spreidik@vt.edu
URN etd-91498-143821
Title Numerical Simulations of Interactions Among Aerodynamics, Structural Dynamics, and Control Systems
Degree PhD
Department Engineering Mechanics
Advisory Committee
Advisor Name Title
Mook, Dean T. Committee Chair
Batra, Romesh C. Committee Member
Durham, Wayne C. Committee Member
Hendricks, Scott L. Committee Member
Nayfeh, Ali H. Committee Member
Perumpral, John V. Committee Member
Wolfe, Mary Leigh Committee Member
Keywords
  • Flutter
  • Unsteady Nonlinear Aeroelasticity
  • Wings
Date of Defense 1998-10-01
Availability unrestricted
Abstract
A robust technique for performing numerical simulations of nonlinear

unsteady aeroelastic behavior is developed. The technique is applied to

long-span bridges and the wing of a modern business jet. The heart of the

procedure is combining the aerodynamic and structural models. The

aerodynamic model is a general unsteady vortex-lattice method. The

structural model for the bridges is a rigid roadbed supported by linear and

torsional springs. For the aircraft wing, the structural model is a

cantilever beam with rigid masses attached at various positions along the

span; it was generated with the NASTRAN program. The structure, flowing air,

and control devices are considered to be the elements of a single dynamic

system. All the governing equations are integrated simultaneously and

interactively in the time domain; a predictor-corrector method was adapted

to perform this integration.

For long-span bridges, the simulation predicts the onset of flutter

accurately, and the numerical results strongly suggest that an actively

controlled wing attached below the roadbed can easily suppress the

wind-excited oscillations. The governing equations for a proposed passive

system were developed.

The wing structure is modelled with finite elements. The deflections are

expressed as an expansion in terms of the free-vibration modes. The

time-dependent coefficients are the generalized coordinates of the entire

dynamic system. The concept of virtual work was extended to develop a method

to transfer the aerodynamic loads to the structural nodes. Depending on the

speed of the aircraft, the numerical results show damped responses to

initial disturbances (although there are no viscous terms in either the

aerodynamic or structural model), merging of modal frequencies, the

development of limit-cycle oscillations, and the occurrence of a

supercritical Hopf bifurcation leading to motion on a torus.

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  bibliography.pdf 89.55 Kb 00:00:24 00:00:12 00:00:11 00:00:05 < 00:00:01
  chapter1.pdf 461.57 Kb 00:02:08 00:01:05 00:00:57 00:00:28 00:00:02
  chapter2.pdf 2.42 Mb 00:11:12 00:05:45 00:05:02 00:02:31 00:00:12
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  introduction.pdf 95.11 Kb 00:00:26 00:00:13 00:00:11 00:00:05 < 00:00:01

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