A joined 3D/1D finite element method for aeroservoelastic analysis of damaged HALE aircraft wings
Sadat Hoseini Khajuee, Seyed Mohammad Hanif
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Nonlinear aeroelastic analysis of damaged High-Altitude-Long-Endurance aircraft wings is considered. The structural model consists of a full three-dimensional finite element continuum model for the damaged area, which is a small localized area of the wing, and a geometrically exact one-dimensional displacement-based finite element model for the undamaged part of the wing. The solid and the beam parts are then rigorously combined using a transformation between the joined nodes of the two models at their intersection. The transformation is derived using the recovery equations of variational asymptotic beam model and employed to eliminate the six degrees of freedom of the single joined node of the beam. The validity and efficiency of the method is demonstrated using test cases involving cracks and delaminations in the solid part. It is shown that although the accuracy remains virtually the same between the full three-dimensional model and the joined one-dimensional/three-dimensional model, the computational cost is considerably lower for the latter. Finite-state induced flow theory of Peters is exploited as the unsteady aerodynamic model to compute aerodynamic forces and moments acting on the wing. Combining the structural and aerodynamic models, a dynamic nonlinear aeroelastic element is developed for the time simulation of the dynamic responses of composite high aspect-ratio wings. The model has been used for analyzing aeroelastic instability boundaries and time simulations, as well as synthesizing an active flutter suppression control system. Numerical results verifying the validity of the method are presented and the results are discussed. The proposed joined model will enables the High-Altitude-Long-Endurance aircraft designers to tackle the problem of aeroelasticity in a computationally efficient manner, without sacrificing accuracy with regard to full three-dimensional models, hence reducing the overall time and cost of the design process.