Environmental Engineering Reference
In-Depth Information
(e)
Wood, laminated composite, for 50 kW unit.
(f )
FRPs, airfoil LS1, hand lay up in three molds, top and bottom skins are attached
to nose, D-spar with lead weight, for 300 kW unit.
(g)
Extruded aluminum, bottom from three pieces, the others from two pieces, for
VAWT 34 m test bed, 500 kW.
FIGURE 6.16
(Continued)
A blade on a wind turbine goes through more fatigue cycles in 1 year than the wings on an air-
plane during its lifetime; therefore, fatigue is the major concern since the wind loads are large and
variable. Even though metal blades have been built for wind turbines, their fatigue properties are not
satisfactory, which resulted in too many failures. Carbon filaments are used in blades because they
are stronger, even though they are more costly than glass filaments. The limitation on the pultruded
FRP blades is that the blades are constant chord with no twist. For FRP blades there is the cost for
the master mold, and there is a trade-off between automated winding of filaments and hand lay up.
Molds are expensive and dies for the extruded aluminum blades are even more expensive.
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