Aeroelastic optimization of stick models for parametric flutter investigations in blended-wing-body aircraft
Date
2026
Authors
Bravo, Diogo
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Abstract
This work focuses on assessing the aeroelastic behaviour of a Blended-Wing-Body (BWB) aircraft configuration and proposes a model order reduction framework to enable systematic parametric analysis on aerodynamic shape and structural properties. A high-fidelity baseline aeroelastic model is first developed and assessed under ultimate loading conditions in accordance with certification requirements. Modal analysis identifies the dominant bending and torsional modes governing the dynamic response, and the Modal Assurance Criterion (MAC) is used to assess modal coupling. Aeroelastic investigations reveal two critical instabilities within the flight envelope: symmetric and antisymmetric bending-torsion flutter (BTF).
A reduced-order stick model (SM) was calibrated through an optimization workflow to replace the flexible wing in a hybrid configuration. This condensation approach reduces computational cost for aeroelastic analysis while preserving the physical significance of the model. Three case studies are conducted to match the static deformation, modal response, and aeroelastic behaviour of the full GFEM. Dedicated error metrics are introduced to quantify discrepancies in vertical displacement, twist, natural frequencies, and mode shapes.
Two novel aeroelastic metrics are proposed: an eigenvalue error metric based on the Error Vector Magnitude (EVM) concept and a robust complex mode shape metric tailored for complex aeroelastic eigenvectors. The optimized hybrid model predicts flutter speed within 3% error and accurately reproduces the underlying instability mechanisms, while significantly reducing computational effort.
To better understand the flutter mechanisms of the BWB configuration, the reduced-order model is used in a parametric study involving six geometric and structural parameters. The study characterizes the evolution of flutter mechanisms across the BWB design space. For the 600 configurations evaluated, the governing instability was bending-torsion flutter (BTF). The proposed methodology can suggest modifications to the configuration capable of raising the flutter speed by up to 30%.
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Keywords
blended-wing-body aircraft, reduced-order model, multi-objective optimization, aeroelasticity, bending-torsion flutter, parametric study