Finite element analysis and design of connection strength of a segmented composite wind turbine blade

Based on a fluid-solid coupling analysis of a 59.5 m full-scale blade, this paper proposes a scarf adhesive/embedded bolt sleeve hybrid connection configuration for a segmented composite blade. The segmentation occurs 18 m from the blade root. By incorporating aerodynamic loads calculated using the blade element momentum (BEM) theory, as well as gravity loads and stud preloads, finite element analysis (FEA) is performed using ABAQUS software to assess the stress, strain, displacement, and damage behaviors of the segmented blade under the wind speeds 10 m/s and 15 m/s. The bilinear cohesive model and finite-thickness cohesive elements in ABAQUS are employed to predict the adhesive layer's damage behaviors. Numerical results reveal that: (1) except at the segmented location, the mechanical performance of the segmented blade closely mirrors that of the full-scale blade; (2) under the wind speeds 10 m/s and 15 m/s, initial adhesive failure occurs almost across the entire adhesive layer under low cohesive strength 5 MPa, although significant cohesive stiffness degradation does not occur; and (3) a mixed-mode fracture (open/shear) is evident under low cohesive strength 5 MPa, while shear fracture dominates under high cohesive strength 30 MPa.