Robust Flutter Analysis Considering Mode Shape Variations

Heinze, Sebastian; Borglund, Dan

doi:10.2514/1.28728

Cited by 13 publications

(11 citation statements)

References 12 publications

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“…The latter methodology enables the uncertain parameter to be associated with the physical one, at the cost of neglecting its effect on the modes (which are kept at their nominal values in the decomposition). The effect of this assumption in real applications has been evaluated in Heinze and Borglund,31 where possible strategies to limit the impact of this assumption are also discussed.…”

Section: State-space Approachmentioning

confidence: 99%

Aeroelastic modeling and stability analysis: A robust approach to the flutter problem

Iannelli

Marcos

Lowenberg

2017

Intl J Robust & Nonlinear

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SummaryIn this paper, a general approach to address modeling of aeroelastic systems, with the final goal to apply μ analysis, is discussed. The chosen test bed is the typical section with unsteady aerodynamic loads, which enables basic modeling features to be captured and so extend the gained knowledge to practical problems treated with modern techniques. The aerodynamic operator has a nonrational dependence on the Laplace variable s, and hence, 2 formulations for the problem are available: frequency domain or state-space (adopting rational approximations). The study attempts to draw a parallel between the 2 consequent linear fractional transformation modeling processes, emphasizing critical differences and their effect on the predictions obtained with μ analysis. A peculiarity of this twofold formulation is that aerodynamic uncertainties are inherently treated differently and therefore the families of plants originated by the possible linear fractional transformation definitions are investigated. One of the main results of the paper is to propose a unified framework to address the robust modeling task, which enables the advantages of both the approaches to be retained.On the analysis side, the application of μ analysis to the different models is shown, emphasizing its capability to gain insight into the problem.

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Section: State-space Approachmentioning

confidence: 99%

Aeroelastic modeling and stability analysis: A robust approach to the flutter problem

Iannelli

Marcos

Lowenberg

2017

Intl J Robust & Nonlinear

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“…To comply with the notation used in previous work on robust flutter analysis [7,10], Eq. (6) can be rewritten according to…”

Section: Linear Fractional Transformation Form Of Mass Matrixmentioning

confidence: 99%

“…A concern in robust analysis with varying structural properties is, however, that the modal base Z depends on these variations. In a previous study [10], the impact of mode-shape variations was investigated, and different ways to account for it were proposed. A summary of these approaches is given next.…”

Section: Modal Reductionmentioning

confidence: 99%

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Assessment of Critical Fuel Configurations Using Robust Flutter Analysis

Heinze

2007

Journal of Aircraft

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An approach to assess critical fuel configurations using robust flutter analysis is presented. A realistic aircraft model is considered to demonstrate how an available finite element model can be adapted to easily apply robust flutter analysis with respect to structural variations such as fuel-level variations. The study shows that standard analysis tools can be used to efficiently generate the system data that are required to perform robust flutter analysis. The -k method is used to compute the worst-case flutter speed, and the corresponding worst-case fuel configuration is found. The main advantage of the proposed approach is that analysis guarantees robustness with respect to all possible fuel configurations represented by the tank model.

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“…The -k formulation also opened up new possibilities to model aerodynamic uncertainty, which is of primary importance in aeroelastic applications. Some additional developments in this direction can be found in [7][8][9][10].…”

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confidence: 99%

Robust Eigenvalue Analysis Using the Structured Singular Value: The µ-p Flutter Method

Borglund

2008

AIAA Journal

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This paper introduces a new technique for robust aeroelastic analysis that extends standard linear flutter analysis to take deterministic uncertainty and variation into account. The basic principle of the proposed -p method is to exploit structured-singular-value (or ) analysis to investigate if the system uncertainties can make the flutter determinant zero for a given flutter eigenvalue p. This makes it possible to compute regions of feasible eigenvalues in the complex plane as well as extreme eigenvalues that can be used to predict damping bounds and perform robust flutter analysis. The capability to predict damping bounds at subcritical flight conditions is a very attractive feature of the new method, as flight testing is rarely taken to the flutter point. The -p formulation also opens up new possibilities to bound the magnitude of the system uncertainties based on frequency and/or damping estimates from flight testing. In the final part of the paper, the -p framework is successfully applied to perform robust aeroelastic analysis of a low-speed wind-tunnel model. Nomenclature F= flutter matrix F u = upper linear fractional transformation g = damping K = stiffness matrix k = reduced frequency L = reference length M = mass matrix N = linear fractional transformation matrix P = system matrix p = eigenvalue Q = aerodynamic matrix V = airspeed w = input from uncertainty matrix z = output to uncertainty matrix = uncertainty matrix = uncertainty parameters = modal coordinates = structured singular value = modal force = air density = maximum singular value

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Robust Flutter Analysis Considering Mode Shape Variations

Cited by 13 publications

References 12 publications

Aeroelastic modeling and stability analysis: A robust approach to the flutter problem

Aeroelastic modeling and stability analysis: A robust approach to the flutter problem

Assessment of Critical Fuel Configurations Using Robust Flutter Analysis

Robust Eigenvalue Analysis Using the Structured Singular Value: The µ-p Flutter Method

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