Parametric investigation on stepped-lap scarf repair of wind turbine blade spar cap

A prediction method based on the stepped-lap repair strength was proposed to study the parameterization of repairing the damaged wind turbine blade spar cap structure. First, the numerical analysis model of spar cap damage was established based on the continuous damage mechanics model, the puck criterion, and the cohesive zone model. Then, the influence of the repair parameters on the repair strength was studied based on the stepped-lap repair theory. Finally, the optimal repair scheme was determined by a strength recovery rate analysis. Results demonstrate that increasing lap length and the number of overply layers can enhance the load-carrying capacity of the stepped-lap repair structure within a certain range. Lap length and the number of overply layers substantially affect the bearing capacity of the spar cap. The influence of the overply layer is slightly higher than that of the lap length, while the lap width effect remains relatively minor.