Tension–Tension Fatigue and Flammability Behavior of Fire-Resistant Carbon Fiber Composites for Fire Drone Applications

This study evaluates the fatigue and flammability performance of TC1810/T1100GC fire-resistant carbon fiber composites for structural components in firefighting and surveillance drones. Tension–tension fatigue tests provide a conservative measure of material durability, as resistance to tensile fatigue generally indicates good performance under flexural loading. Static tensile and flexural tests were conducted to establish baseline strengths and assess performance under both axial and bending-dominated conditions. Composite laminates with a [0/90]6S stacking sequence were fabricated and subjected to load-controlled tension–tension fatigue using a sinusoidal waveform at 5 Hz and a stress ratio of R = 0.1. Thermal behavior was further characterized via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) to assess material stability under high-temperature conditions. The flame retardancy was evaluated using Limiting Oxygen Index (LOI) testing, with the material exhibiting an LOI greater than 55%, confirming its strong fire resistance. Fatigue life decreased with increasing stress levels, while specimens loaded at 40% of ultimate tensile strength (UTS) survived one million cycles without failure. Stiffness degradation trends revealed early-stage matrix damage followed by gradual fiber–matrix debonding. These results demonstrate that TC1810/T1100GC composites provide a favorable combination of mechanical endurance and flame resistance, making them suitable for aerial systems operating in thermally and mechanically demanding environments.