Relationship of Composite Repair Methods and Damage Accumulation to Residual Strength in Wind Turbine Blades

Abstract

The rapid global expansion of wind energy infrastructure has necessitated a profound understanding of the structural longevity of wind turbine blades. As these critical components scale up in size to capture more energy, they are subjected to increasingly complex and severe aerodynamic, gravitational, and environmental loads. Over time, these cyclic and stochastic loading conditions lead to microscopic and macroscopic damage accumulation, ultimately degrading the residual strength of the composite materials from which the blades are constructed. This paper provides a comprehensive academic analysis of the mechanisms governing damage accumulation in composite wind turbine blades and evaluates the efficacy of various composite repair methods in restoring structural integrity. By synthesizing current literature, non-destructive testing methodologies, and structural analysis techniques, the study elucidates how specific repair configurations, such as stepped and tapered scarf joints, influence the recovery of ultimate load capacity. Furthermore, the research investigates the long-term behavior of repaired sections under variable amplitude loading, highlighting the challenges of in-situ field repairs, including environmental contamination and suboptimal curing conditions. The findings emphasize that while advanced composite repair strategies can significantly mitigate the effects of damage accumulation and prolong the operational lifespan of turbine blades, the precise execution of surface preparation and material matching remains critical to maximizing residual strength.