Ultraviolet (UV) curable resin-based repair of wind turbine blades: Perspectives and computational analysis

Abstract

The repair of wind turbine blades is essential for extending their operational lifespan by restoring their structural integrity after property degradation due to damage. Application of ultraviolet (UV)-curable prepregs in the repair process reduces curing time from hours to minutes compared to traditional thermal curing, presenting significant potential for drastic reduction in repair costs. However, thermal and chemical strain differences and the presence of voids can lead to cure-induced residual stresses in repaired section of the blades. A numerical framework is used in this paper to evaluate these residual stresses in wind turbine blade sections repaired using UV-curable prepregs. To repair thick laminates, multi-stage repair is investigated, which shows a 13 % reduction in residual stresses compared to single-stage repair. The post-repair behaviour of the repaired section is studied by performing experimental and numerical analysis on tensile samples obtained from the repaired composites. Debonding between the repair patch and the substrate composite starts at approximately 60 % of the failure load. The developed model can assist in designing advanced repair protocols that minimize residual stresses and enhance the long-term performance of composite wind turbine blades by optimizing the cure parameters in UV-based repair methods.