The Effect of Single and Multi‐Factor Coupling on the Aging Failure of T700 Carbon Fiber Composite Material in the Simulated Polar Environment

ABSTRACT The effect of single factor and multi‐factor coupling of the Polar environment on the aging failure of T700 carbon fiber‐reinforced polymer (CFRP) composite material is investigated. The mechanical performance degradation of T700‐CFRP depends on environmental conditions. The interlayer shear strength decreases by about 50% (80°C‐95% RH and 60°C‐5% NaCl) after aging in a single factor environment. In contrast, the decrease in tensile strength is much smaller (< 16%), indicating that shear performance is more sensitive to environmental exposure. The effect of a single environmental factor on performance degradation of T700‐CFRP is limited, while the coupling effect of multiple factors leads to a tensile strength retention rate approximately 14% lower than that observed under the single polar factor of −70°C or UV environment. The main cause of performance degradation is the invasion of moisture into the resin matrix and fiber/resin interface, which leads to bond degradation and microcrack propagation, ultimately resulting in matrix cracking and interface debonding under the influence of environmental factors. Furthermore, the application of a mechanical load during aging acts as a significant accelerator, intensifying the damage process and leading to a more substantial decrease in the strength retention rate.