Nonlinear Stability Analysis of Control Surface Flutter with Freeplay Effects

Gordon, Jason; Meyer, Edward E.; Minogue, Robert L.

doi:10.2514/1.31901

Cited by 39 publications

(26 citation statements)

References 24 publications

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“…The overall behavior of the airfoil is provided by the characteristic equation of the [4x4] matrix defined by the terms a 2 \, a 22 , a 23 , a 4 i, a 42 , and <z 43 . This equation will be different depending on every instant plunge value.…”

Section: Equations Of Motionmentioning

confidence: 99%

A revision of the flutter margin method to predict in real-time the limit cycle oscillations onset speed with structural freeplay present in the plunge axis

Corpas

Lobera

González-Requena

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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Computational fluid dynamic and order reducing methods have been extensively applied to predict the flutter onset speed of several types of aircrafts. However, the accuracy required by certification standards still ascribes flight testing as the only method available that safely validates the flight envelope of an aircraft. In particular, free-flutter conditions must be demonstrated in the target flight envelope, and several methods have been developed to determine the flutter onset speed in real-time when expanding the envelope during flight testing. Among the methods, the damping versus velocity technique combined with a flutter margin implementation remains the most common technique used for envelope expansion. Even with the popularity and "easy to implement" characteristics of this method, several shortcomings can adversely affect the identification of non-stable conditions during envelope expansion. Notably, the limit cycle oscillations conditions, distinct from flutter, cannot be accurately identified. This study proposes to apply a similar methodology to the flutter margin to anticipate limit cycle oscillations associated with freeplay in the plunge axis of a bi-dimensional airfoil that is aeroelastically representative of the tested aircraft. Analytical considerations are conducted to support this new approach, and a computer model is used to validate the proposed methodology.

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Section: Equations Of Motionmentioning

confidence: 99%

A revision of the flutter margin method to predict in real-time the limit cycle oscillations onset speed with structural freeplay present in the plunge axis

Corpas

Lobera

González-Requena

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part G:

View full text Add to dashboard Cite

show abstract

“…These stiffness elements are usually modeled with a single degree-of-freedom with no stiffness coupling between it and other degrees-of-freedom [4]. A describing function for bilinear stiffness k jj associated with generalized coordinate j, with stiffness k 0 when the displacement amplitude |q j | is below δ and k 1 when it is above, is:…”

Section: Matrix Parameterizationsmentioning

confidence: 99%

“…Single nonlinearities, for example free play or bilinear stiffness in one discrete degree-of-freedom, have been studied for many years [3,4]. A single nonlinearity modeled with a describing function is readily treated with linear flutter techniques, since the generalized coordinates can be normalized to satisfy the amplitude of the single generalized coordinate.…”

Section: Introductionmentioning

confidence: 99%

Continuation Methods for Nonlinear Flutter

Meyer¹

2016

Aerospace

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Continuation methods are presented that are capable of treating frequency domain flutter equations, including multiple nonlinearities represented by describing functions. A small problem demonstrates how a series of continuation processes can find all limit-cycle oscillations within a specified region with a reasonable degree of confidence. Curves of the limit-cycle amplitude variation with velocity, indicating regions of stability and instability with colors, give a compact view of the nonlinear behavior throughout the flight regime. A continuation technique for reducing limit-cycle amplitudes by adjusting various system parameters is presented. These processes are economical enough to be a routine part of aircraft design and certification.

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“…A three-part procedure to ensure the full bifurcation behavior of an aeroelastic system with freeplay was proposed by Dimitriadis [4]. The nonlinear stability analyses of a three-degree-of-freedom typical-section airfoil with freeplay were conducted in [5], limit-cycle amplitudes predicted by the describing function method were shown to compare very well with the magnitudes of time-history responses. The aeroelastic responses of a missile control surface with freeplay were investigated using describing function method (DFM) in [6], and the results showed the LCOs could be obtained at velocities below the linear flutter velocity.…”

Section: Introductionmentioning

confidence: 99%

The Aeroelastic Characteristic of a Wing with Preload Asymmetry Freeplay

Zhang¹,

Wu²

2015

Procedia Engineering

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Nonlinearities in designing aircraft are inevitable. It is necessary to investigate the effects of them on the dynamic response. The aeroelastic dynamic model with freeplay nonlinearity in pitch degree of freedom is established with the Theodorsen aerodynamic model. The harmonic balance method is employed to obtain the flutter boundary. Then the nonlinear responses and the stability characteristic are studied by using the time marching aeroelastic method. The effects of the initial displacement in pitch degree of freedom and the gap size on the LCO characteristics are investigated. Results show that the appearance of the LCO depends on the initial condition and the flow speed. The velocity range for the existence of the LCO and the LCO amplitude are related to the freeplay gap.

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Nonlinear Stability Analysis of Control Surface Flutter with Freeplay Effects

Cited by 39 publications

References 24 publications

A revision of the flutter margin method to predict in real-time the limit cycle oscillations onset speed with structural freeplay present in the plunge axis

A revision of the flutter margin method to predict in real-time the limit cycle oscillations onset speed with structural freeplay present in the plunge axis

Continuation Methods for Nonlinear Flutter

The Aeroelastic Characteristic of a Wing with Preload Asymmetry Freeplay

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