scholarly journals Aeroelastic Stability Analysis of Damaged High-Aspect-Ratio Composite Wings

2019 ◽  
Vol 56 (5) ◽  
pp. 1794-1808
Author(s):  
Hanif S. Hoseini ◽  
Dewey H. Hodges
Keyword(s):  
Stability Analysis ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Aeroelastic Stability

scholarly journals Geometrical Nonlinear Aeroelastic Stability Analysis of a Composite High-Aspect-Ratio Wing

2008 ◽  
Vol 15 (3-4) ◽  
pp. 325-333 ◽  
Author(s):  
Chang Chuan Xie ◽  
Jia Zhen Leng ◽  
Chao Yang
Keyword(s):  
Stability Analysis ◽  
Aspect Ratio ◽  
Equilibrium State ◽  
High Aspect Ratio ◽  
Unsteady Aerodynamics ◽  
Static Equilibrium ◽  
Beam Model ◽  
Aeroelastic Stability ◽  
Nonlinear Flutter ◽  
Static Equilibrium State

A composite high-aspect-ratio wing of a high-altitude long-endurance (HALE) aircraft was modeled with FEM by MSC/NASTRAN, and the nonlinear static equilibrium state is calculated under design load with follower force effect, but without load redistribution. Assuming the little vibration amplitude of the wing around the static equilibrium state, the system is linearized and the natural frequencies and mode shapes of the deformed structure are obtained. Planar doublet lattice method is used to calculate unsteady aerodynamics in frequency domain ignoring the bending effect of the deflected wing. And then, the aeroelastic stability analysis of the system under a given load condition is successively carried out. Comparing with the linear results, the nonlinear displacement of the wing tip is higher. The results indicate that the critical nonlinear flutter is of the flap/chordwise bending type because of the chordwise bending having quite a large torsion component, with low critical speed and slowly growing damping, which dose not appear in the linear analysis. Furthermore, it is shown that the variation of the nonlinear flutter speed depends on the scale of the load and on the chordwise bending frequency. The research work indicates that, for the very flexible HALE aircraft, the nonlinear aeroelastic stability is very important, and should be considered in the design progress. Using present FEM software as the structure solver (e.g. MSC/NASTRAN), and the unsteady aerodynamic code, the nonlinear aeroelastic stability margin of a complex system other than a simple beam model can be determined.

Aeroelastic Stability Analysis of Aircraft Wings with High Aspect Ratios by Transfer Function Method

2018 ◽  
Vol 18 (12) ◽  
pp. 1850150 ◽  
Author(s):  
Jing Bo Duan ◽  
Zhong Yuan Zhang
Keyword(s):  
Stability Analysis ◽  
Transfer Function ◽  
Aspect Ratio ◽  
Eigenvalue Problem ◽  
High Aspect Ratio ◽  
Function Method ◽  
Complex Eigenvalue ◽  
Governing Equations ◽  
Aeroelastic Stability ◽  
Transfer Function Method

A new method is developed for the aeroelastic stability analysis of a high-aspect-ratio wing based on the transfer function. First, the flutter governing equations for three types of wing elements including clear wing element, wing element with a control surface and that with an external store are, respectively, established by combining the corresponding bend-twist vibration model with the Theodrosen’s unsteady aerodynamic model. Then, in order to use the transfer function method, the element governing equations are processed by the Fourier transform and are formulated in a state-space form using state vector. Based on the finite element procedure, the global governing equations of the whole wing are obtained. Both the flutter velocity and flutter frequency are derived by solving a complex eigenvalue problem with the graphical approach. Additionally, the torsional divergence of the high-aspect-ratio wing is obtained by solving a real eigenvalue problem, which is a degenerated form of the wing flutter governing equations. Finally, illustrative examples are prepared to demonstrate the validity of the present method, which is insensitive to mesh density and does not require structural modal analysis for aeroelastic stability.

scholarly journals Direct Use of Unsteady Aerodynamic Pressures in the Flutter Analysis of Mistuned Blades

1994 ◽  
Author(s):  
A. V. Srinivasan ◽  
G. G. Tavares
Keyword(s):  
Stability Analysis ◽  
Aspect Ratio ◽  
Unique Feature ◽  
Mode Shapes ◽  
Complex Eigenvalue ◽  
Aeroelastic Stability ◽  
Low Aspect Ratio ◽  
Unsteady Aerodynamic ◽  
Flutter Analysis ◽  
Direct Use

An aeroelastic stability analysis of a cascade of engine blades coupled only through aerodynamica is developed. The unique feature of the analysis is the direct use of unsteady aerodynamic pressures, rather than lifts and moments, in calculating the susceptibility of a cascade to flutter. The approach developed here is realistic and relevant for analysis of low aspect ratio blades. However, in the calculations presented in this paper, the surface is assumed to be divided into equal elemental areas. The formulation leads to a complex eigenvalue problem, the solution of which determines the susceptibility of the cascade to flutter. The eigenvalues of an assembly of alternately mistuned blades, operating at high reduced frequencies, appear to be very sensitive to the level of mistuned frequencies. The locus of eigenvalues shows a strong tendency to split even for very small percentage differences between the frequencies of the two sets of blades. Further, blades with identical frequencies, but alternately mistuned mode shapes, operating at high reduced frequencies show a tendency towards instability.

Effect of shooting and blast-induced gust on nonlinear aeroelastic stability and behavior of high-aspect ratio wing

2018 ◽  
Vol 433 ◽  
pp. 299-313 ◽  
Author(s):  
Pezhman Mardanpour ◽  
Ehsan Izadpanahi ◽  
Siavash Rastkar ◽  
Sukeerth Calastawad ◽  
Cesar Levy
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Aeroelastic Stability ◽  
And Behavior
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