Research Projects

In recent years, fiber-reinforced polymer (FRP) composites have gained widespread use in underwater and marine applications such as submarines, warships, boats, offshore bridges, and wind turbines due to their high specific strength and stiffness. However, the harsh marine environment inevitably subjects FRP composites to seawater aging, significantly impacting their performance. Studies indicate that certain FRP composite materials lose up to 30% of their strength after prolonged exposure to seawater. Additionally, their dynamic load-carrying capability deteriorates substantially, occasionally resulting in catastrophic failures, as seen in the implosion of the Titan submersible. Thus, it is essential to investigate the seawater aging and marine environment fatigue properties of FRP composites and to explore strategies to enhance their aging resistance. To address these challenges and improve the seawater aging resistance of composites, various techniques are employed in industry, including surface coatings, chemical fiber treatments, oxidative treatments, and the incorporation of nanofillers such as carbon nanotubes (CNTs), graphene oxide (GO), Al₂O₃, TiO₂, and SiO₂. Among these, the use of GO and CNTs has shown significant potential for improving the mechanical properties of composites in marine environments by preventing salt pitting on fibers and at the fiber-matrix interface. However, the application of GO and CNTs to enhance the fatigue properties of composites in marine environments has yet to be explored in the literature. Fatigue in FRP composites typically initiates with microcracks that gradually expand, causing minor damage that eventually leads to major fractures. The incorporation of GO and CNTs is expected to mitigate crack initiation and growth, thereby improving the fatigue performance of FRP composites in marine environments. This project aims to experimentally investigate the seawater aging and fatigue behavior of FRP composites and to develop CNT- and GO-based coatings to enhance their marine fatigue and aging resistance. In this regard a series of tests will be conducted in accordance with relevant ASTM standards, including ASTM D3039 for tensile testing, ASTM D6641 for compression testing, ASTM D2344 for shear testing, ASTM D790 for three-point bending, and ASTM D3479/D3479M-96 for fatigue testing. The experimental data will be used for statistical analysis to develop empirical mathematical models that quantify the seawater aging properties of FRP composites.