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1 
A numerical method for fully nonlinear aeroelastic analysisGargoloff, Joaquin Ivan 15 May 2009 (has links)
This work presents a numerical method for the analysis of fully nonlinear aeroelastic
problems. The aeroelastic model consisted of a NavierStokes flow solver, a nonlinear
structural model, and a solution methodology that assured synchronous interaction
between the nonlinear structure and the fluid flow.
The flow around the deforming wing was modeled as unsteady, compressible and
viscous using the Reynoldsaveraged NavierStokes (RANS) equations. To reduce the
computational time, a threelevel multigrid algorithm was implemented and the flow
solver was parallelized. The messagepassing interface (MPI) standard libraries were
used for the parallel interprocessor communication.
The computational domain was divided into topologically identical layers that
spanned from the root to past the tip of the wing. A novel mesh deformation algorithm
was developed to deform the mesh as the structure of the wing was being displaced.
The mesh deformation algorithm was able to handle wing tip deformations of up to
60 % of the wing semispan. Besides being robust, the mesh deforming algorithm was
computationally more efficient than regriding, since deforming an existing mesh was
computationally less expensive than generating a new mesh for each wing position.
Results are presented for the validation and verification of both the flow solver
and the aeroelastic solver. The flow solver was validated using: (1) the flow over
a flat plate, to validate the turbulent model implementation, and (2) the flow over
the NACA 0012 airfoil and over the F5 wing, to validate the implementation of the convective and viscous fluxes, the time integration algorithm, and the boundary
conditions. The aeroelastic solver was validated using: (1) the unsteady F5 wing
undergoing forced pitch motion, and (2) the Nonlinear Aeroelastic Test Apparatus
(NATA) wing. In addition, aeroelastic results were generated for the Goland wing.
The aeroelastic solver developed herein allows the analysis of aeroelastic phenomena
using a fully nonlinear approach. Limit cycle oscillations, which are highly
nonlinear phenomena, were captured by the nonlinearities of the flow solver and the
structural solver. The impact of the nonlinearities was assessed for the Goland wing,
where nonlinear terms changed dramatically the aeroelastic behavior of the wing.

2 
Integrated aerodynamicstructural wing design optimization /Unger, Eric Robert, January 1992 (has links)
Thesis (Ph. D.)Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 7479). Also available via the Internet.

3 
Active control of booster elasticity /Swaim, Robert Lee January 1966 (has links)
No description available.

4 
Effect of Follower Forces on Aeroelastic Stability of Flexible StructuresChae, Seungmook 09 July 2004 (has links)
Missile bodies and wings are typical examples of structures that can be represented by beam models. Such structures, loaded by follower forces along with aerodynamics, exhibit the vehicle's aeroelastic instabilities. The current research integrates a nonlinear beam dynamics and unsteady aerodynamics to conduct aeroelastic studies of missile bodies and wings subjected to
follower forces. The structural formulations are based on a geometricallyexact, mixed finite element method. Slenderbody theory and thinairfoil theory are used for the missile aerodynamics, and twodimensional finitestate unsteady aerodynamics is used for wing aerodynamics. The aeroelastic analyses are performed using timemarching scheme for the missile body stability, and eigenvalue analysis for the wing flutter, respectively. Results from the timemarching formulation agree with published results for dynamic stability and show the development of limit cycle oscillations for disturbed flight near and above the critical thrust. Parametric studies of the aeroelastic behavior of specific flexible missile configurations are presented, including effects of flexibility on stability, limitcycle amplitudes, and missile loads. The results do yield a significant interaction between the thrust, which is a follower force, and
the aeroelastic stability. Parametric studies based on the eigenvalue analysis for the wing
flutter, show that the predicted stability boundaries are very sensitive to the ratio of bending stiffness to torsional stiffness. The effect of thrust can be either stabilizing or
destabilizing, depending on the value of this parameter. An assessment whether or not the magnitude of thrust needed to influence the flutter speed is practical is made for one
configuration. The flutter speed is shown to change by 11% for this specific wing configuration.

5 
Nonlinear Analysis of a Two DOF Piecewise Linear Aeroelastic SystemElgohary, Tarek Adel Abdelsalam 2010 August 1900 (has links)
The nonlinear dynamic analysis of aeroelastic systems is a topic that has been covered extensively in the literature. The two main sources of nonlinearities in such systems, structural and aerodynamic nonlinearities, have analyzed numerically, analytically and experimentally. In this research project, the aerodynamic nonlinearity arising from the stall behavior of an airfoil is analyzed. Experimental data was used to fit a piecewise linear curve to describe the lift versus angle of attack behavior for a NACA 0012 2 DOF airfoil. The piecewise linear system equilibrium points are found and their stability analyzed. Bifurcations of the equilibrium points are analyzed and applying continuation software the bifurcation diagrams of the system are shown. Border collision and rapid/Hopf bifurcations are the two main bifurcations of the system equilibrium points. Chaotic behavior represented in the intermittent route to chaos was also observed and shown as part of the system dynamic analysis. Finally, sets of initial conditions associated with the system behavior are defined. Numerical simulations are used to show those sets, their subsets and their behavior with respect to the system dynamics. Poincaré sections are produced for both the periodic and the chaotic solutions of the system. The proposed piecewise linear model introduced some interesting dynamics for such systems. The introduction of the border collision bifurcation and the existence of periodic and chaotic solutions for the system are some examples. The model also enables the understanding of the mapping of initial conditions as it defines clear boundaries with different dynamics that can be used as Poincaré sections to understand further the global system dynamics. One of the constraints of the system is its validity as it is dependent on the range of the experimental data used to generate the model. This can be addressed by adding more linear pieces to the system to cover a wider range of the dynamics.

6 
Nonlinear aeroelastic analysis of high aspectratio wings using the method of numerical continuationNichkawde, Chetan 16 August 2006 (has links)
This research explores the impact of kinematic structural nonlinearities on the
dynamics of a highly deformable cantilevered wing. Two different theoretical formulations
are presented and analysed for nonlinear behavior. The first formulation, which
is more conventional, assumes zero equilibrias and structural nonlinearities occur as
terms up to third order in the Taylor series expansion of structural nonlinearities.
In the second approach, no prior assumption about equilibria states of the wing is
made. Kinematic nonlinearities due to curvature and inertia were retained in their
exact form. Thus, the former becomes a special case of the latter. This nonlinear formulation
permits the analysis of dynamics about nonzero trims. Nonzero trim states
are computed as a system parameter is varied using a continuation software tool. The
stability characteristics of these trim states are also ascertained. Various bifurcation
points of the system are determined. Limitcycle oscillations are also investigated for
and are characterized in terms of amplitude of vibration. The research in particular
examines the impact of inplane degree of freedom on the stability of nonzero trim
states. The effect of variation of system parameters such as stiffness ratio, aspect
ratio and root angle of attack is also studied. The method of direct eigenanalysis of
nonzero equilibria is novel and new for an aeroelastic system.

7 
Designoriented gust stress contraints for aeroservoelastic design synthesis /Engelsen, Frode. January 2001 (has links)
Thesis (Ph. D.)University of Washington, 2001. / Vita. Includes bibliographical references (leaves 100108).

8 
Reduced order models and control of large scale aeroelastic simulationsFagley, Casey P. January 2008 (has links)
Thesis (M.S.)University of Wyoming, 2008. / Title from PDF title page (viewed on July 14, 2009). Includes bibliographical references (p. 43).

9 
Gust alleviation in aircraft using forward mounted control surfacesTherrien, Francois Xavier, 1928 January 1962 (has links)
No description available.

10 
Analytical and experimental studies of a helicopter rotor in vertical flightNagaraja, Kanivenahalli Sreenivasa 05 1900 (has links)
No description available.

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