Dynamic Strength - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 119

5

Dynamic St rength

5.1 StressandVibrationAnalysisof

CompositeWindTurbineBlades
5.1.1 Introduction

Wind.turbine.blades.work.under.extreme.and.changeable.wind.loads,.espe-
cially.in.winter.with.ice.storms.and.during.the.summer.with.hurricanes.and.
rain. storms.. Displacements. of. blades. depend. on. the. stiffness. of. iberglass.
and.deformations.that.create.stresses.and.possible.failure..We.can.analyze.
this.environmental.situation.by.using.the.laminate.theory.
Composite. propeller. blades. work. similar. to. helicopter. rotors. and. fans,.
which.have.been.manufactured.in.a.laminate.form.from.iberglass.and.car-
bon.iber,.reinforced.with.epoxy..The.blade.skin.also.is.made.with.aramid.
iber,.which.also.has.been.reinforced.with.epoxy.resin..Additional.reinforce-
ment.is.necessary.due.to.the.impact.of.birds.on.the.leading.edge,.which.is.
made.from.thermoplastics.to.protect.the.laminated.layers.
The.carbon.ibers.with.reinforced.epoxy.resin.have.been.oriented.in.vari-
ous.directions..Changing.the.iber.direction.in.the.layers.can.turn.the.torsion.
and.bending.stiffness.of.composite.blades.

5.2 StressAnalysisofPropellerBlades

The.natural.frequencies.of.propeller.turbine.blades.can.be.favorably.placed.
in.an.area.outside.the.operational.rpm.range..This.following.relates.the.eval-
uation.of.the.force.and.free.vibration.frequencies.for.the.purpose.of.avoiding.
the.noise.air.and.ground.resonance..In.the.early.1970s,.composite.propeller.
blades.with.reinforced.epoxy.were.utilized.throughout.the.world. 1 .Propeller.
blades.and.fans.were.manufactured.from.iberglass,.which.was.protected.by.
special. polymers. 2 . For. impact. protection,. the. leading. edge. was. covered. by.
thin.copper.inputted.in.the.prepreg.package.during.compression.molding..

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