Nonlinear Aeroelastic Analysis of Joined-Wing Aircraft with Fully Intrinsic Equations

Sotoudeh, Zahra; Hodges, Dewey H.

doi:10.2514/6.2009-2464

Cited by 10 publications

(7 citation statements)

References 6 publications

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“…(1), with the boundary conditions (4) and forcing terms given by Eqs. (10)- (12). These nonlinear equations will be solved after projection on the vibration modes of the linear structure, which are obtained next.…”

Section: Nonlinear Equations In Intrinsic Modal Coordinatesmentioning

confidence: 99%

“…Noting that the induced angle of attack can be written as a function of the local inertia velocity in their components in a frame linked to the airfoil, one can write the aeroelastic equations of motion with structural nonlinearities purely in terms of velocities. This approach has been already followed by Patil, Hodges and co-workers 8,[10][11][12] to obtain compact flight dynamics models of very flexible aircraft. Those authors used a finite-difference approximation to the spatial component of the equations of motion, and also extended the analysis to cases with closed kinematic chains (which requires the enforcement of a unique solution along multiple load paths) using an incremental solution approach.…”

Section: Introductionmentioning

confidence: 99%

“…Those authors used a finite-difference approximation to the spatial component of the equations of motion, and also extended the analysis to cases with closed kinematic chains (which requires the enforcement of a unique solution along multiple load paths) using an incremental solution approach. 12 In this paper, the intrinsic form of the nonlinear aeroelastic equations of motion will be projected on the linear normal modes (also expressed in intrinsic variables) of the flexible wing, which will be used to obtain a reduced-order model for nonlinear time-domain and stability analyses. Numerical examples will be finally used to validate and evaluate the performance of the solution procedure, that will be compared with results from conventional displacement-based aeroelastic models.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An Intrinsic Description of the Nonlinear Aeroelasticity of Very Flexible Wings

Palacios

Epureanu

2011

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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A modal solution is presented to the aeroelastic equations of very flexible wings in intrinsic form, that is written using inertial velocities and strains as primary variables. After assuming 2-D thin-airfoil aerodynamics on the wing sections, it is shown that the equations of motion can be written in canonical state-space form on the intrinsic modal coordinates without any matrix inversion and including only quadratic nonlinearities. Flutter characteristics are readily obtained from a linearized description of the dynamics equations, and the approach provides an efficient way of computing the nonlinear response with large wing displacements. Both situations are exemplified numerically on the Golang wing. The use of modal coordinates will serve to highlight some of the particular characteristics of the use of intrinsic beam solutions in aeroelastic problems with geometrical nonlinearities.

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Section: Nonlinear Equations In Intrinsic Modal Coordinatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Intrinsic Description of the Nonlinear Aeroelasticity of Very Flexible Wings

Palacios

Epureanu

2011

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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“…If the full nonlinear strain-displacement relations are used along with some measure of rotation, the advantages of the fully intrinsic equations are lost. To avoid this, the authors developed an alternative approach based on an incremental method [23], In this method, a linearized form of Eqs. (I) and (2) is used along with linearized strain-displacement equations.…”

Section: Statically Indeterminate Structuresmentioning

confidence: 99%

Modeling Beams With Various Boundary Conditions Using Fully Intrinsic Equations

Sotoudeh

Hodges

2011

Journal of Applied Mechanics

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The fully intrinsic equations for beams comprise a relatively new set of equations for nonlinear modeling of structures comprised of beams. These equations are geometrical!)! exact and constitute a closed set of equations even though they include neither displacement nor rotation variables. They do not suffer from the singularities and infinite-degree nonlinearities normally associated with finite rotation variables. In fact, they have a maximum degree of nonlinearity equal to 2, In spite of these and other advantages of these equations, using them for problems with certain boundary conditions may not be straightforward. This paper will examine the challenges of modeling various boundary conditions using fully intrinsic equations, thus helping future re,vearchers to decide whether or not the fully intrinsic equations are suitable for solving a specific problem and elucidating pathways for their application to more general problems,

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“…Firstly, recent literature [19,20,21] highlights the need to consider potential aeroelastic instabilities that may arise when using the joined-wing configuration. For example, Weisshaar and Lee [22] showed that, depending on the position of the centre of gravity, the joined-wing has the potential for body-freedom flutter involving interaction between the elastic modes and the aircraft pitch mode.…”

Section: Limitations Of This Analysismentioning

confidence: 99%

Buckling Alleviation for Joined-Wing Aircraft

Lambert

Cooper

Nangia

2015

56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. University of Bristol, BS8 1TR, United KingdomA novel mechanism is described that increases the critical buckling load of the rear wing of joinedwing aircraft, in an effort to reduce structural weight. The benefits of the joined-wing configuration are briefly discussed, along with its current limitations. The behaviour of the modified structure under lift is investigated by conducting a number of linear structural analyses for varying geometric arrangements. It is shown that the mechanism, called the Buckling Alleviation Component (BAC), is effective in reducing structural weight for a significant proportion of aircraft geometries, even though there is a trade-off between rear wing buckling load and front wing root bending moment. A more detailed structural model is used to investigate the effect of geometric structural nonlinearities. The nonlinear analysis shows that the BAC delays the onset of nonlinear behaviour and that the critical buckling loads of the conventional configuration are drastically overestimated by the linear analysis, which means that BAC performs much more effectively than the initial linear analysis suggests.

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Nonlinear Aeroelastic Analysis of Joined-Wing Aircraft with Fully Intrinsic Equations

Cited by 10 publications

References 6 publications

An Intrinsic Description of the Nonlinear Aeroelasticity of Very Flexible Wings

An Intrinsic Description of the Nonlinear Aeroelasticity of Very Flexible Wings

Modeling Beams With Various Boundary Conditions Using Fully Intrinsic Equations

Buckling Alleviation for Joined-Wing Aircraft

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