Mechanical characterization of protective coatings for offshore wind turbine towers and transition pieces

Marine coatings develop residual stresses in all stages of their lifetime; excessive residual stresses affect adhesion and can compromise the integrity of both the coating system and substrate. The mechanical properties of three epoxy-based paint systems for offshore wind turbine towers and transition pieces were determined by dynamic mechanical analysis in 3-point bending mode. The coatings were airless sprayed onto steel substrates and cured. A mathematical model using composite beam stress analysis was developed to determine the Young's modulus of the coatings. The results show that the mechanical properties of the coatings depend on the film thickness. The composite modulus and Young's modulus of the coatings decrease when the coating thickness increases. Understanding the mechanical properties of marine coatings, and the factors which influence them, could lead to further improvements in the coating and corrosion protection of offshore structures in general.