Materials for Turbine Power Blades, Reinforcements, and Resins - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 70

resistant.to.80°C..Araldite.2005.is.resistant.to.water.and.to.a.wide.range.of.
chemicals. 13,14 . Carbon/cyanate. ester. composites. were. proposed. as. replace-
ments.for.the.carbon/epoxy.composites.with.improved.out-gassing,.micro-
cracking,.and.moisture.absorption.characteristics. 15

3.6 CoreMaterials:HoneycombSandwich

StructuresandAdhesives
3.6.1 Introduction

The.ibers.and.the.matrix.are.combined.in.making.wind.turbine.blades..The.
principal.design.has.selected.shells.and.core.materials,.which.carry.propor-
tional.loads.that.are.created.by.the.bending.and.torsion.moments..Leading.
and.trailing.edges.unsupported.by.inner.webs.is.composed.of.carbon.ibers,.
with.a.stiffness.two.times.greater.than.glass.ibers.

3.6.2 Core Materials

Blade. manufacturing. core. materials. are. used. primarily. for. large-area,.
unsupported.stability.in.leading/trailing.edge.panels.and.shear.webs.
Core.materials.include:.end.grain.balsa,.foam.cores.(PVC,.SAN,.Urethane,.
PET-extruded. form),. engineered. core. materials. (Webcor. TYCOR ® ,.
NexCore™)..End.grain.balsa.has.high.shear.properties.and.low.cost,.but.is.
higher.in.weight..Pet-extruded.forms.are.less.cost.effective.and.are.lighter.
TYCOR.material.(iber-reinforced.core).applied.to.shear.webs.in.the.mid-
dle.of.the.blade,.has.very.low.weight.and.a.high.performance.core.at.a.highly.
competitive.price..Kitting.and.assembly.in.the.mold.has.proved.to.be.faster.
and.more.accurate.than.balsa.and.foam.material. 21
Fiber. reinforced. composites. consist. of. closed-cell. polyisocyanurate. foam.
(compression.strength:.30.kg/m 3 ),.glass.iber.reinforcement.(E-glass.roving.
mat),.and.binders.
TYCOR. ibers. with. reinforced. core. preforms. are. made. with. dry. iber. and.
foam..Final.mechanical.properties.of.TYCOR.are.achieved.by.infusion.molding.
A.comparison.of.leading.blade.core.materials.is.listed.in.Table 3.12.
Properties.of.TYCOR.W.Core.include: 21

•. Statistical.transverse.properties.of.25.4.mm.TYCOR.W.molded.with.
Hexion.135i.epoxy.resin,.six-specimen.samples
•. Comparisons.with.supplier-published.data.for:
•. 60.kg/m3.PVC.foam.(Alcan.Airexâ.C70.55).average.values
•. 155.kg/m 3 .balsa.(Diab.ProBalsaâ.PB,.“Average”.and.“Minimum”.
values)