Degradation and Strength Prediction of CFRP Under Hygrothermal‐Mechanical Coupling Environment

ABSTRACT Composites have great potential in the field of marine and offshore structures due to their high specific strength and excellent corrosion resistance. In this paper, the moisture absorption behavior and mechanical properties of CFRP under combined aging conditions of water/seawater at 70°C and compressive loading environments are investigated. FTIR, DMA, and microstructural characterization were carried out to reveal the damage mechanism of the composites under extreme aging conditions. The results show that compression loading along the fiber direction reduces the moisture, and the reduction of mechanical properties is mainly affected by interfacial degradation. In the seawater environment, the compressive strength of specimens affected by post‐curing increased by 13% at the beginning of aging but decreased by 7.2% after 2016 h of immersion. Flexural strength showed a single degradation trend, which was aggravated by the coupling of external compressive loads. The long‐term evolution of compressive and flexural strengths was predicted based on the Arrhenius equation and Fick model, respectively. The three‐parameter Weibull model was used to describe the residual flexural strength data in different aging environments and to predict the safe strength at various aging times. It is expected to provide insight into the application of composite materials in marine structures.