Environmental Engineering Reference
In-Depth Information
1.000
Ceramics
Composites
CFRP
100
Metals
and alloys
GFRP
10
Porous
ceramics
Wood and
wood products
Polymers
1
0.1
Foams
Rubbers
0.01
100
300
1,000
3,000
10,000
30,000
FIGURE 3.2
Diagram. correlation. between. stiffness. and. density.. (From. Bronstead,. Litholt,. and. Lystrup..
2005..Composite.materials.for.wind.power.turbine.blades..Technical.University.of.Denmark,.
p..510..With.permission.)
moderate.stiffness..Carbon.is.used.in.root.blades.and.leading.edges.in.spite.
of.the.high.cost.because.it.has.speciic.strength.and.stiffness.
Fiber.and.composites.properties.are.shown.in.Table 3.2. 1
Glass.iber.has.an.amorphous.structure.with.isotropic.properties,.but.carbon.
iber.has.a.crystallographic.lattice.with.a.hexagon.shape,.which.is.called.graphite.
So,. the. stiffness. of. a. carbon. iber. is. ive. times. greater. than. glass. iber,. if.
geometrical.axis.of.a.blade.consists.of.iber.orientation.(orientation.0°).
. Thermoset. matrices. most. used. are. polyesters,. vinyl. esters,. and. epoxy,.
which.are.soft.and.lexible.(low.stiffness.of.less.than.4.GPa).to.help.bind.the.
ibers.together,.work.like.an.interface,.and.give.functional.composites.a.struc-
tural.purpose..Finally,.stiffness.of.the.carbon.composites.is.4.6.times.greater.
than.glass.composites.and.tensile.strength.is.1.3.times.higher,.but.the.density.
of.carbon.composites.is.less..In.turbine.blades,.glass.ibers.and.carbon.ibers.
are.based.on.hybrid.construction..The.hybrid.concept.is.often.a.compromise.
between.the.improved.performance.of.carbon.ibers.and.their.high.cost.
 
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