Experimental investigation on the tensile strength degradation of CFRP tendons with anchorage systems under seawater immersion

Mooring lines are critical components for floating offshore wind turbines (FOWT). Carbon fibre-reinforced polymer (CFRP) has emerged as a promising alternative to traditional engineering materials due to its exceptional mechanical properties. To investigate the feasibility of CFRP tendons as mooring systems in terms of durability, this paper delves into the mechanisms underlying the tensile strength degradation of CFRP tendons equipped with anchors exposed to marine environments. Accelerated tests in artificial seawater were conducted on CFRP tendons with anchorage systems, and scanning electron microscopy (SEM) was used to analyse microstructure changes. The tensile strength retention of CFRP tendons at depths of 30 and 300 m in various sea regions of China was predicted according to the Arrhenius theory. The results show that the seawater temperature significantly affects the tensile strength of CFRP tendons because high temperature accelerates the epoxy resin decomposition. After 6 months of exposure to seawater at 60 °C, the tensile strength decreased by 34.3%. The epoxy resin between fibres underwent varying degrees of decomposition at different temperatures, and the anchors protected the internal CFRP tendon and provided sufficient anchor efficiency, indicating that the mechanical type of anchor is suitable for CFRP tendons in marine environments.