| 摘要 |
PROBLEM TO BE SOLVED: To provide a further lighter blade structure of a state having a higher bending fatigue strength than that of prior art. SOLUTION: The blade structure 1 of a windmill made of an FRP containing reinforcing fibers and the resin having a width W, a flange 10 of a girder having a width Wf of a range of 0.2 to 0.5 W at sectional central positions 3 and 4 of gravity of the blade 1, carbon fiber-reinforced resin layers 14 and high elongation fiber-reinforced resin layers 15 alternately laminated thereon. In this case, a total thickness 2Tf occupying the upper and lower flanges 10 of a composite layer 17 is in a range of 10 to 30% of the thickness T of the blade. The layer 17 is a laminate containing a carbon fiber-reinforced resin layer having a thickness of at least one layer oriented in a longitudinal direction of the blade of at least 70% or more of its volume is 16 mm, and the glass fiber-reinforced resin layer having a thickness of 0.2 to 1.5 mm. |
