Nonlinear aeroelastic modelling for flexible aircraft with multibody wings
File(s)
Author(s)
Cheng, Kelvin Chi-Wing
Type
Thesis
Abstract
The aviation industry's growth outlook is increasingly anchored in the transition to net-zero emissions by 2050, with more efficient aircraft an important lever in the decarbonisation pathway. High aspect-ratio wing designs promise structural weight savings, unlocked by the understanding of the dynamics of flared hinged wingtips, as a passive load alleviation mechanism. Modelling the coupled flight dynamics and aeroelastics requires careful treatment of the full system of rigid-body, aeroelastic, and constraint equations, since the wing and wingtips can independently undergo large translations, deformations and rotations. This is enabled by simulations using the nonlinear aeroelastic toolbox SHARPy capturing those nonlinearities in play.
Implementation and validation of a flexible multibody aeroelastic formulation was carried out in the SHARPy nonlinear multibody aeroelastic solver, with results benchmarked against computational and experimental references to assess the geometric and aerodynamic nonlinearities modelled. To characterise the load alleviation mechanisms and to assess the nonlinearities in full aircraft dynamic response, the formulation is put to the test on both a high-altitude long-endurance (HALE) aircraft model and a representative next-generation flexible aircraft configuration, each tested with and without freely-flying wingtips.
Parametric sweeps in the definition of the aircraft and gust for the HALE vs its hinged sibling, the H2ALE, give results demonstrating that flared hinged wingtips achieve static and dynamic wing root bending moment alleviation compared to fixed configurations, with load relief mechanisms driven by hinge flare angle, wing flexibility, and wingtip mass distribution. Analysis on the flexible representative aircraft SuperFLEXOP / Hinged-SuperFLEXOP uncovers nonlinear phenomena including bifurcation at higher gust intensities where the coupled rigid-elastic-multibody system exhibits transitions between equilibrium branches. The framework demonstrates potential for design maturation of next-generation sustainable aircraft architectures, enabling virtual testing for advancing understanding of coupled multibody aeroelasticity and flight dynamics beyond the limitations of linear methods.
Implementation and validation of a flexible multibody aeroelastic formulation was carried out in the SHARPy nonlinear multibody aeroelastic solver, with results benchmarked against computational and experimental references to assess the geometric and aerodynamic nonlinearities modelled. To characterise the load alleviation mechanisms and to assess the nonlinearities in full aircraft dynamic response, the formulation is put to the test on both a high-altitude long-endurance (HALE) aircraft model and a representative next-generation flexible aircraft configuration, each tested with and without freely-flying wingtips.
Parametric sweeps in the definition of the aircraft and gust for the HALE vs its hinged sibling, the H2ALE, give results demonstrating that flared hinged wingtips achieve static and dynamic wing root bending moment alleviation compared to fixed configurations, with load relief mechanisms driven by hinge flare angle, wing flexibility, and wingtip mass distribution. Analysis on the flexible representative aircraft SuperFLEXOP / Hinged-SuperFLEXOP uncovers nonlinear phenomena including bifurcation at higher gust intensities where the coupled rigid-elastic-multibody system exhibits transitions between equilibrium branches. The framework demonstrates potential for design maturation of next-generation sustainable aircraft architectures, enabling virtual testing for advancing understanding of coupled multibody aeroelasticity and flight dynamics beyond the limitations of linear methods.
Version
Open Access
Date Issued
2025-12-01
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Palacios Nieto, Rafael
Sponsor
Engineering and Physical Sciences Research Council
Airbus Industrie
Grant Number
EP/W522004/1
Publisher Department
Department of Aeronautics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)