Manufacturing Technologies for Turbine Power Blades - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 91

Filament. winding. is. a. sensible. way. of. placing. a. huge. amount. of. roving.
around.a.rotating.mandrel.in.a.controlled.manner..The.shape.of.wind.tur-
bine.blade.is.similar.to.an.aviation.proile.shape.and.the.majority.of.the.ibers.
have. to. be. placed. along. the. blade. length.. Therefore,. the. ilament. winding.
technique. had. to. be. developed. further. for. this. speciic. application.. In. the.
United. States,. a. technique. for. winding. the. entire. blade. was. developed. by.
Kaman. Aerospace. Corporation. and. Structural. Composite. Industries,. for.
blades.up.to.45.m.in.length.using.glass.iber. 3-5 .A.set.of.three.mandrels.was.
used.to.gradually.build.up.the.airfoil.with.integrated.webs..First,.the.leading.
edge. part. and. the. forward. shear. web. were. wound. around. the. irst. man-
drel,.then.a.second.mandrel.was.attached.to.the.already.wound.leading.edge.
structure,. and. more. ibers. were. wound. onto. the. two. combined. mandrels.
adding.more.materials.to.the.irst.structure.and.forming.a.second.shear.web..
Finally.a.third.mandrel.was.attached,.and.more.winding.created.the.after-
body.with.the.trailing.edge..The.winding.was.done.with.a.combination.of.
glass. iber. roving. and. a. glass. iber. tape;. most. of. the. ibers. winding. in. the.
transverse.direction.of.the.tape.
Figure 4.1.illustrates.how.the.iber.rovings.are.wound.around.steel.bushes.
to.form.the.lange..This.special.bias.tape.was.necessary.to.achieve.suficient.
bending.stiffness.and.strength.of.the.wind.turbine.blade..It.is.dificult.and.
ineficient.to.place.rovings.along.the.axis.of.mandrels.with.a.ilament.wind-
ing.machine..A.tape.winding.technique.for.winding.the.spar,.including.the.
leading.edge.and.the.shear.web,.was.also.developed.in.Denmark.by.Risoe.
National.Laboratory.and.the.Volund.Company.in.the.late.1970s. 6 .The.blades.
of.the.two.Nibe.wind.turbines.were.20.m.long.and.were.a.hybrid.construc-
tion.consisting.of.a.steel.spar.for.the.inner.8.m.and.a.glass.iber/polyester.
spar.for.the.outer.12.m.of.the.blade.(Figure 4.2).

Steel spar

Bearing housing

Hub

Connection arrangement

Shell
Outer wing Inner wing

Principal of the nibe blades

FIGURE 4.2
Principal.of.the.Nibe.blades:.The.inner.8.m.has.a.steel.spar..(From.P..Brondsted,.H..Lilholt,.and.
A..Lystrup..2005.. Composite material for wind power turbine blades. .Roskilde,.Denmark:.Annual.
Reviews,.A.nonproit.scientiic.publisher..With.permission.)