Comparative Thermomechanical Performance of CFRP and PETG for UAV Structures under Thermal Extremes

The selection of structurally resilient and thermally stable materials is critical in the design of unmanned aerial vehicle (UAV) frames that operate in varied environmental conditions. In this study, two candidate materials, Carbon Fiber Reinforced Polymer (CFRP) and Polyethylene Terephthalate Glycol (PETG), were systematically evaluated for their thermomechanical performance. Standardized ASTM tests were conducted on samples conditioned at − 10°C, 40°C, and 55°C for 12 hours, simulating the typical operational environments experienced by UAVs. CFRP specimens were tested using ASTM D3039-17 (tensile), ASTM D7264/D7264M-21 (flexural), and ASTM D2344/D2344M-22 (short-beam shear), while PETG samples were tested using ASTM D638-14 for tensile behavior. Mechanical properties including ultimate tensile strength, flexural strength, and interlaminar shear strength were recorded and analyzed in megapascals (MPa). The results reveal that CFRP retained approximately 91.7% of its tensile strength across temperatures with minimal degradation, while PETG showed a tensile strength reduction ranging from 11.1% to 20.2%, along with a marked shift from brittle to ductile failure behavior. Fractographic analysis confirmed distinct failure patterns across temperature regimes. These findings establish a material selection benchmark and support CFRP as the preferred material for UAV structures in harsh or variable thermal environments.