Continuum damage mechanics based computational framework for prediction of the lifetime and degradation of wind turbine coatings with defects

Abstract

The repeated raindrop impact significantly decreases the life of wind turbine blades (WTB) coating. Several computational frameworks have been developed in the literature to understand the damage behaviour and to predict the safe life of WTB's coating under such conditions. Experimental findings show that coatings may contain voids which adversely affect the coating's life. However, the computational models of coating often ignore this effect. This paper develops a new framework based on Continuum Damage Mechanics (CDM) to predict the life of WTB’s coating with voids due to rain. To determine the fatigue life of WTB’s coating, (i) a stochastic rain field simulation model has been employed, which provides data on the raindrop size distribution and impact locations. (ii) The stresses due to the impact of these raindrops are computed using smoothed particle hydrodynamics. (iii) Thereafter, CDM is implemented to predict fatigue damage life. Since damage can be visualized as nucleation and propagation of pits, voids, and cracks, hence, the complete life of the wind turbine blade's coating can be predicted by CDM. The computational result of the proposed CDM framework has been verified with fatigue damage results available in the literature. This study establishes that the proposed CDM-based computational framework is a reliable tool to predict the rain-induced fatigue life of the blade's coating in the presence of flaws.