Micromechanical model of surface erosion of polyurethane coatings on wind turbine blades

An analytical model of rain erosion of coatings from segregated polyurethanes is developed. The model proposes an interrelation between the structure and morphology of segregated polyurethanes, damping properties and the erosion lifetime. For linking viscoelastic properties and the morphology of segregated polyurethanes, the embedded box model is used. With view on the available observations about the high variability of blade erosion and role of manufacturing defects, the critical role of statistical, random effects for the erosion damage initiation is assumed, and the statistical theory of strength is applied for the damage and fatigue analysis of the coatings. It is observed that the larger is the mechanical loss coefficient tan δ, the less is the stored elastic energy in the material after the impact. Further, it is observed that the higher the mechanical loss coefficient (damping) of the coating material, the higher is the lifetime of the coating under the erosion conditions.