Initiation Mechanism of Transverse Cracks in Wind Turbine Blade Trailing Edge

Transverse crack often occurs in the trailing edge region of the bladewhen subjected to the excessive edgewise fatigue load.In this paper a refined model was established through local mesh refinement methods in order to investigate the initiation mechanism of crack and its extension in blade trailing edge.The material stress around the crack in trailing edge region under different thicknesses is calculated based on the fracture mechanics theory.The factors affecting the fatigue robustness of blade trailing edge are concluded by investigating the results of finite element analysis and coupons test.Compared with the laminate,the lower fatigue strength of the adhesive is the cause of the transverse crack of the adhesive joint at the trailing edge.The increase of the adhesive thickness at the adhesive joint will significantly increase the stress concentration factor at the crack region and accelerate the crack extension of the laminate.In final,a practical design scheme to prevent crack initiation is given for the manufacture of the wind turbine blade.