Structural assessment and experimental validation of a hybrid composite–polymer trailing-edge morphing wing for low-Reynolds-number UAVs

Abstract Trailing-edge morphing wings have emerged as a promising solution for enhancing aerodynamic efficiency in low-Reynolds-number unmanned aerial vehicles (UAVs); however, their structural performance under large deformation and actuation-driven loading remains inadequately understood. This study presents a comprehensive structural assessment and experimental demonstration of a hybrid composite–polymer trailing-edge morphing wing (TEMW). The proposed configuration integrates zigzag compliant ribs, carbon-fibre load-bearing members, and a silicone-based flexible skin to achieve smooth and continuous camber variation. A geometrically nonlinear finite element framework is developed to evaluate deformation behaviour, equivalent stress distribution, stiffness variation, strain energy, and structural safety under controlled morphing actuation. Comparative analyses are conducted for plated and un-plated configurations to quantify the influence of structural reinforcement. Results reveal a near-linear relationship between morphing angle and deformation (R² ≈ 0.999), while stress and strain energy exhibit strong nonlinear growth, increasing by up to 2.5× and 8×, respectively. Structural reinforcement enhances stiffness by approximately 12.6% and improves safety margins by up to 8% at lower morphing angles, though its effectiveness diminishes at higher deflections due to dominant geometric nonlinearity. A composite performance index (CPI) is introduced to evaluate morphing efficiency, demonstrating a rapid decline beyond moderate deflection limits. Furthermore, morphing-induced loads are found to exceed aerodynamic loads by nearly three orders of magnitude, establishing actuation as the governing design driver. Experimental observations show good qualitative agreement with numerical predictions, validating the proposed modelling approach with a maximum deviation below 4% between numerical and experimental deformation. The findings provide critical insights into structural design trade-offs and establish a robust framework for the development of reliable morphing wing systems for UAV applications.