Comparative assessment of natural fiber-reinforced polymer PET/PETG composites for sustainable UAV materials

This study presents an innovative evaluation of natural fiber-reinforced PET and PETG composites for UAV wing structures operating under NEOM wind conditions, defined by a mean wind speed of 5.6 m/s and peak gusts of 12 m/s. Aerodynamic analysis demonstrated a stable lift-to-drag ratio of 15.8 across the operating range, while lift increased quadratically from 1.75 N at 3 m/s to 77.95 N at 20 m/s. Thrust demand remained nearly constant between 4.79 and 4.85 N, indicating efficient propulsion stability under variable airflow conditions. A Multi-Criteria Decision-Making framework was developed to rank candidate materials using specific stiffness (40%), specific strength (30%), and carbon footprint (30%). The results established a clear performance hierarchy led by Ramie/PETG, which achieved the highest overall score through exceptional specific stiffness of 35.5 GPa·cm 3 /g and a low carbon footprint of 1.64 kg CO 2 e/kg. Ramie/PET ranked second, delivering the highest tensile strength of 372.6 MPa together with strong specific stiffness of 29.4 GPa·cm 3 /g. The PETG matrix consistently surpassed PET because of its higher modulus (1.95 vs 1.094 GPa), lower density (1.27 vs 1.60 g/cm 3 ), and narrower carbon footprint range. These findings identify Ramie/PETG as the preferred solution for UAV wings requiring maximum flutter resistance, while Ramie/PET is recommended where peak structural strength is the primary design objective.