Efficient aeroelastic beam modelling and the selection of a structural shape basis

The work presented in this paper describes the modelling of a low-order aeroelastic solver, built with the aim of analysing the dynamics of very flexible wing aircraft, with a focus on the coupling between the flight dynamics and the structural dynamics. The model implements a geometrically exact, low-order nonlinear beam solver based on beam shape functions coupled with Vortex Lattice Method (VLM), specifically adapted to account for large deformations. The static solution calculated by implementing the VLM was compared with the one calculated using strip theory as aerodynamic solver, showing good agreement in magnitude, but different load distribution. The aeroelastic solver was then used to analyse the dynamics of a flexible aircraft constrained to a circular trajectory with free pitch (resembling the motion on a Pendulum Rig) and on a spherical motion with free pitch and yaw (resembling the motion on the University of Bristol 5-DOF Manoeuvre Rig), for two different values of pitch stiffness and three different flexible wings (5% deflection, 10% deflection and 15% deflection with respect to the wing semispan). The results show that when the stiffness is high, it suppresses any interaction between the flight dynamics and the structural dynamics. Therefore there is no impact of the wing flexibility on the aircraft motion. On the other hand, when lowering the value of the pitch stiffness, the interaction between the wing dynamics and the pitch dynamics become evident. However, the impact of the wing flexibility was found to be always negligible on the yaw dynamics.

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“…For a full derivation and simple test-case validation studies, including the selection of a structural shape basis, see [24,26].…”

Section: B Nonlinear Beam Shapes (Nbs) Structural Solvermentioning

confidence: 99%

Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

Pontillo

Navaratna

Ascham

et al. 2022

AIAA SCITECH 2022 Forum

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“…For this task, the code was enabled with a Fluid-Structure Interaction (FSI) algorithm responsible for coupling the structural and aerodynamic models by recurring to a loosely coupled scheme (where despite fluid and structure models being solved separately, the solution only advances in time when convergence between fluid and structure models is reached) that ensures consistency, but not energy conservation. Despite the use of low-medium fidelity aerodynamic (3D panel method with viscous and compressibility corrections) and structural (3D condensed beam model based on wing-box mass and inertia calculations) models, their applicability to preliminary design is adequate since they capture the main physical phenomena and allow exploring the design space [35,36]. The aerodynamic, structural and aeroelastic models were benchmarked [33,34] with existing data available in the literature.…”

Section: Aeroelastic Frameworkmentioning

confidence: 99%

On the Design of Aeroelastically Scaled Models of High Aspect-Ratio Wings

et al. 2020

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Recently, innovative aircraft designs were proposed to improve aerodynamic performance. Examples include high aspect ratio wings to reduce the aerodynamic induced drag to achieve lower fuel consumption. Such solution when combined with a lightweight structure may lead to aeroelastic instabilities such as flutter at lower air speeds compared to more conventional wing designs. Therefore, in order to ensure safe flight operation, it is important to study the aeroelastic behavior of the wing throughout the flight envelope. This can be achieved by either experimental or computational work. Experimental wind tunnel and scaled flight test models need to exhibit similar aeroelastic behavior to the full scale air vehicle. In this paper, three different aeroelastic scaling strategies are formulated and applied to a flexible high aspect-ratio wing. These scaling strategies are first evaluated in terms of their ability to generate reduced models with the intended representations of the aerodynamic, structural and inertial characteristics. Next, they are assessed in terms of their potential in representing the unsteady non-linear aeroelastic behavior in three different flight conditions. The scaled models engineered by exactly scaling down the internal structure suitably represent the intended aeroelastic behavior and allow the performance assessment for the entire flight envelope. However, since both the flight and wind tunnel models are constrained by physical and budgetary limitations, custom built structural models are more likely to be selected. However, the latter ones are less promising to study the entire flight envelope.

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Nonlinear aeroelastic analysis of a damped elastica-aerofoil system

Jayatilake

Titurus

2022

Nonlinear Dyn

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This work formulates a comprehensive model of a nonlinear aeroelastic system developed for the analysis of complex aeroelastic phenomena related to structural and aerodynamic nonlinearities. The system is formulated as a two-dimensional cantilevered elastica with a rigid airfoil section firmly attached at its tip undergoing large displacements in the crosswind conditions. The system can demonstrate a wide range of domain specific as well as coupled nonlinear phenomena. The structural model is developed by means of the Rayleigh–Ritz approach, with shape functions discretizing both vertical and horizontal displacements and Lagrangian multipliers enforcing inextensibility. Damping is modeled based on a non-local strain-based mechanism in the Kelvin–Voigt arrangement. The resulting structural model is examined through studying the behavior under a follower load and with a tip-attached tendon under tension to study the shape convergence properties and the alignment of the results with known characteristics in the literature. The ONERA dynamic stall model is used to model the aerodynamics of the problem to accurately capture post-stall behavior at large deformations. The LCO responses of the aeroelastic problem are evaluated through time-marched simulations, and the combined airspeed–damping interactions are studied in this manner.

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Efficient aeroelastic beam modelling and the selection of a structural shape basis

Cited by 5 publications

References 19 publications

Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

Low-order Aeroelastic Modelling of a High Aspect Ratio Wing Aircraft Under Constrained Motion

On the Design of Aeroelastically Scaled Models of High Aspect-Ratio Wings

Nonlinear aeroelastic analysis of a damped elastica-aerofoil system

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