Linear and Nonlinear Aeroelastic Analysis of a High Aspect Ratio Wing

2017 ◽  
Author(s):  
F. Bakhtiari-Nejad ◽  
A. H. Modarres ◽  
E. H. Dowell ◽  
H. Shahverdi
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Structural Model ◽  
State Space Model ◽  
Beam Model ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Linear And Nonlinear ◽  
Perturbation Equations

In this study, analysis and results of linear and nonlinear aeroelastic of a cantilever beam subjected to the airflow as a model of a high aspect ratio wing are presented. A third-order nonlinear beam model is used as structural model to take into account the effects of geometric structural nonlinearities. In order to model aerodynamic loads, Wagner state-space model has been used. Galerkin method is implemented to solve dynamic perturbation equations about a nonlinear static equilibrium state. The small perturbation flutter boundary is determined by these perturbation equations. The effect of geometric structural nonlinearity of the beam model on the flutter behavior is significant. As it is observed the system’s response to upper speed of flutter goes to limit cycle oscillations and also the oscillations lose periodicity and become chaotic.

scholarly journals Aeroelastic Modeling and Analysis of High Aspect Ratio Wings With Different Fidelity Structural Models

2019 ◽  
Author(s):  
Gökçen Çiçek ◽  
Altan Kayran
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Structural Model ◽  
Structural Models ◽  
Element Model ◽  
Modeling And Analysis ◽  
Aeroelastic Analysis ◽  
Lifting Surfaces ◽  
Nonlinear Finite Element Model

Abstract This paper is concerned with the aeroelastic modeling and analysis of high aspect ratio wings with large torsional deflections with different fidelity structural models. The approach for structural modeling presented here is based on linear and nonlinear theories. The linear theories are based on the slender-straight wing and bending-torsion beam finite element formulations. The nonlinear theory is based on the nonlinear finite element model with only a torsional rotation degree of freedom to study the static aeroelastic behavior. The aerodynamic theory used for aeroelastic coupling is ESDU 95010 [1], which uses steady lifting-surface theory based on Multhopp-Richardson’s solution to provide the spanwise loading of lifting surfaces with camber and twist. Analyses are performed with three different structural models coupled with ESDU for simple plate-like wing models. The results of linear structural models are verified with MSC NASTRAN® and the nonlinear structural model results are verified with the work of Trahair [2]. Linear aeroelastic models are compared with the MSC NASTRAN® solution performed by SOL144. Significant differences in torsional deflection of tip location are observed between the linear and the nonlinear solution methodologies. The linear theory is found to be conservative for the aeroelastic analysis of high aspect ratio wings.

Limit Cycle Flutter Analysis of a High-Aspect-Ratio Wing with an External Store

2014 ◽  
Vol 912-914 ◽  
pp. 907-910 ◽  
Author(s):  
Jun Xu ◽  
Xiao Ping Ma
Keyword(s):  
Aspect Ratio ◽  
Limit Cycle ◽  
High Aspect Ratio ◽  
Structural Model ◽  
Bifurcation Diagrams ◽  
Governing Equations ◽  
Time Simulation ◽  
Flutter Analysis ◽  
Structural Nonlinearities ◽  
Limit Cycle Flutter

Limit cycle flutter analysis of a high-aspect-ratiowing with an external store is presented. The concentrated store mass iscombined into the governing equations which are obtained using the extendedHamilton’s principle. The high-aspect-ratio wing structural model, which alsoconsiders the in-plane bending motion, is used. Three possible nonlinearitiesare considered including structural nonlinearities, aerodynamic nonlinearities,and store nonlinearities. Time simulation and bifurcation diagrams areperformed to analysis systems with three nonlinearities.

scholarly journals High-Fidelity Fin–Actuator System Modeling and Aeroelastic Analysis Considering Friction Effect

2021 ◽  
Vol 11 (7) ◽  
pp. 3057
Author(s):  
Jin Lu ◽  
Zhigang Wu ◽  
Chao Yang
Keyword(s):  
System Modeling ◽  
Past Research ◽  
High Fidelity ◽  
Aeroelastic Stability ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Actuator System ◽  
Friction Models ◽  
Comparison Of The Results

Both the dynamic characteristics and structural nonlinearities of an actuator will affect the flutter boundary of a fin–actuator system. The actuator models used in past research are not universal, the accuracy is difficult to guarantee, and the consideration of nonlinearity is not adequate. Based on modularization, a high-fidelity modeling method for an actuator is proposed in this paper. This model considers both freeplay and friction, which is easy to expand. It can be directly used to analyze actuator characteristics and perform aeroelastic analysis of fin–actuator systems. Friction can improve the aeroelastic stability, but the mechanism of its influence on the aeroelastic characteristics of the system has not been reported. In this paper, the LuGre model, which can better reflect the friction characteristics, was integrated into the actuator. The influence of the initial condition, freeplay, and friction on the aeroelastic characteristics of the system was analyzed. The comparison of the results with the previous research shows that oversimplified friction models are not accurate enough to reflect the mechanism of friction’s influence. By changing the loads, material, and geometry of contact surfaces, flutter can be effectively suppressed, and the power loss caused by friction can be minimized.

Absolute Nodal Coordinate Formulation With Vector-Strain Transformation for High Aspect Ratio Wings

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Keisuke Otsuka ◽  
Yinan Wang ◽  
Kanjuro Makihara
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Degrees Of Freedom ◽  
Absolute Nodal Coordinate Formulation ◽  
Lattice Method ◽  
Absolute Nodal Coordinate ◽  
Aeroelastic Analysis ◽  
Strain Transformation ◽  
Highly Nonlinear ◽  
Analytical Approaches

Abstract High aspect ratio wings are potential candidates for use in atmospheric satellites and civil aircraft as they exhibit a low induced drag, which can reduce the fuel consumption. Owing to their slender and light weight configuration, such wings undergo highly flexible aeroelastic static and dynamic deformations that cannot be analyzed using conventional linear analysis methods. An aeroelastic analysis framework based on the absolute nodal coordinate formulation (ANCF) can be used to analyze the static and dynamic deformations of high aspect ratio wings. However, owing to the highly nonlinear elastic force, the statically deformed wing shape during steady flight cannot be efficiently obtained via static analyses. Therefore, an ANCF with a vector-strain transformation (ANCF-VST) was proposed in this work. Considering the slender geometry of high aspect ratio wings, the nodal vectors of an ANCF beam element were transformed to the strains. In this manner, a constant stiffness matrix and reduced degrees-of-freedom could be generated while capturing the highly flexible deformations accurately. The ANCF-VST exhibited superior convergence performance and accuracy compared to those of analytical approaches and other nonlinear beam formulations. Moreover, an aeroelastic analysis flow coupling the ANCF-VST and an aerodynamic model based on the unsteady vortex lattice method was proposed to perform the static and dynamic analyses successively. The proposed and existing aeroelastic frameworks exhibited a good agreement in the analyses, which demonstrated the feasibility of employing the proposed framework to analyze high aspect ratio wings.

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.

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