Materials for Turbine Power Blades, Reinforcements, and Resins - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 56

30

Trendline blades < 40 m

25

y = 0.0005x 2,6589

20

15

10

5

0

0 10 20 30

Blade Length (m)

40 50 60 70

FIGURE 3.1
Development. weight. length. correlation.. The. triangle-blade. length. is. 10. to. 20. m.. The. circle-
blade.length.is.30.m..The.reqular.polygon.with.4.sides-blade.length.is.54.m..(From.Bronstead,.
Litholt,.and.Lystrup..2005.. Composite materials for wind power turbine blades ..Technical.University.
of.Denmark,.p..509..With.permission.)

The.two.lines.shown.in.Figure 3.2.are.arbitrary.and.illustrate.lines.of.mate-
rials.that.are.equally.good.in.terms.of.stiffness.and.density.for.a.cantilever.
beam..The.lower.of.the.two.lines.indicates.that.potential.candidate.materials.
are.wood,.composites,.porous.ceramics,.metals,.and.ceramics.
The.bottom.line.has.a.metric.index.of.M b. =.0.003.with.unit.of.E.in.GPa.and.r.
in.kg/m 3 ..If.the.metric.index.is.doubled.to.M b. =.0.006,.the.upper.line.is.valid..
A.sensible.delection.requires.a.material.stiffness.of.10.to.20.GPa..To.illustrate.
in.Figure 3.2,.E.=.15.Gpa.

3.2 StructuralCompositeMaterial

Structural. composite. material. consists. of. reinforcements. and. resins..
Variations. in. reinforcement. materials. and. resin. can. be. used. during. the.
winding.process,.such.as.E-glass,.S-glass,.Kevlar™,.and.carbon.ibers.
Table 3.1.lists.the.mechanical.properties.of.carbon.and.glass.ibers.impreg-
nated.by.epoxy.and.liquid.polymer.resins.
Commercial. glasses. based. on. silica. are. obtained. by. fusing. a. mixture. of.
materials. at. temperatures. ranging. from. 1300. to. 1600°C. 1 . Silica. networks.
(SiO 2 ). are. modiied. by. oxides,. such. as. CaO,. BaO,. Na 2 O,. K 2 O,. and. braked.
Si-O-Si.bridges..In.doing.so,.this.reduces.the.temperature.in.glass-founding.
furnaces.. We. analyzed. glass. for. reduced. cost,. high. speciic. strength,. and.