Structural Analysis of a High Aspect Ratio Aircraft Wing Under Post-Buckling Regime

Pedro Lourenço Figueira Francisco Farinha

Key information

Authors:

Pedro Lourenço Figueira Francisco Farinha (Pedro Lourenço Figueira Francisco Farinha)

Supervisors:

Chiara Bisagni; Afzal Suleman (Afzal Suleman)

Published in

August 27, 2025

Abstract

This thesis investigates the structural behavior of a high aspect ratio composite wingbox within the framework of the ERC NABUCCO project. This project addresses the increasing need for lighter, more efficient aircraft structures by exploiting controlled buckling and post-buckling phenomena. A comprehensive literature review to investigate existing gust load alleviation techniques is conducted, followed by a review on the impact of geometric nonlinearities on skin-stringer separation, modal analysis, and aeroelastic behavior. Using detailed finite element models developed in ABAQUS, a comprehensive sensitivity analysis is performed to evaluate the influence of key design parameters, such as skin thickness, stringer area, and internal rib and stringer configuration, on linear buckling loads and static deflections. Subsequently, non-linear analyses are conducted to characterize the post-buckling regime and associated stiffness reduction, enabling the identification of configurations capable of safely entering and exploiting post-buckling for passive load alleviation without compromising structural integrity. The study further assesses the dynamic response of the optimized wingbox through modal analyses, highlighting the relationship between structural modifications and the wing’s vibration characteristics. Results demonstrate that careful design changes can trigger controlled buckling at predetermined locations, leading to significant reductions in wing root bending moment under gust loading, and supporting the integration of nonlinear effects into conventional aeroelastic design frameworks. The methodologies and findings presented herein contribute to the development of next-generation aircraft wings that leverage adaptive, buckling-driven concepts for enhanced performance and sustainability.