The result indicated that the main courses of fatigue fracture were the third tenon which endures the biggest stress makes smaller and nonuniformity contacting area and the damage of grain boundary.

• 结果表明,叶片榫头第三齿和榫槽的接触面积过小、分布不均匀和材料晶界损伤加速裂纹的萌生与扩展,导致叶片的疲劳断裂。