Manufacturing Technologies for Turbine Power Blades - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 95

are.more.costly.in.dollars.if.we.used.autoclave.technology..In.this.topic,.we.
concentrate. on. development. of. out-of-autoclave. new. technology,. which. is.
less.costly.and.more.effective.for.wind.turbine.blades..We.can.infuse.resin.
in.a.dry.package.or.preliminary.impregnate.textile.iber.and.use.prepregs.to.
create.wind.turbine.blade.structures.

4.6.2 Curing Laminates without Autoclave

The.vacuum.infusion.process.has.been.found.to.be.very.versatile.for.mak-
ing.large.composite.structures..During.the.resin.impregnation.process,.the.
vacuum. causes. the. nucleation. and. formation. of. air. bubbles. from. gasses.
dissolved. in. the. resin. 12 . A. degassing. process,. conducted. in. batches. with. a.
small.quantity.of.a.bubble.nucleation.agent.(Scotch-Brite™).and.an.air-spar-
ing. method. could. reduce. void. formation. in. the. vacuum. infusion. process..
However,. despite. reducing. the. level. of. dissolved. gas,. some. microbubbles.
remain.suspended.due.to.the.viscosity.of.the.resin.and.contribute.to.void.for-
mation..While.these.results.were.quite.encouraging,.there.is.a.need.to.design.
a. system. to. ensure. a. continuous. supply. of. degassed. resin. as. a. better. way.
forward.. In. a. continuous. degassing. system,. it. is. necessary. to. establish. the.
relationship.between.the.degassing.process.quality.and.void.content.reduc-
tion. from. the. perspective. of. strength. and. performance,. besides. signifying.
the.most.viable.method.of.degassing.
Preliminary. cure. impregnates. laminate. layers. at. 50. to. 70. percent. for.
strength.package.increase.reached.by.compression.molding.iberglass.large.
propeller.blades. 7
Ultrasonic.tape.lamination.(UTL).is.a.technique.developed.by.Foster.Miller,.
Inc.. (Waltham,. Massachusetts). to. use. insoniication. to. achieve. heating. and.
consolidation.of.iber-reinforced.composite.materials..In.order.to.induce.con-
solidation.without.damaging.a.iber-reinforced.composite,.a.horn.angle.of.less.
than.90°.is.required..Changing.the.horn.angle.changes.the.stress.state.in.the.
material.during.insoniication.and,.thus,.changes.the.relative.amount.of.energy.
dissipated.by.viscoelastic.heating.of.the.matrix.compared.to.iber.disruption.
Foster.Miller.has.demonstrated.UTL.both.for.consolidation.of.thermoplas-
tic. matrix. composite. materials. and. debulking. of. B-staged. thermoset. pre-
preg.. The. insoniication. curing. process. can. induce. a. very. rapid. localized.
heating,. the. transition. glass. temperature. (Tg). can. be. achieved. in. seconds..
The.viscoelastic.properties.of.the.prepreg.material.at.loading.rates.in.the.20.
to.40.kHz.range.are.very.dificult.to.measure.directly. 13
Launch. vehicles. for. the. U.S.. Space-Based. Infrared. System. will. include.
Titan. launch. vehicles. and. the. Air. Force. Space. Operations. Vehicle. (SOV)..
Composite.structures.on.the.SOV.(the.military.version.of.NASA's.Reusable.
Launch. Vehicle. (RLV)). will. be. too. large. to. cure. inside. existing. autoclaves..
Electron.beam.(EB).processing.is.one.of.the.most.promising.approaches.for.
out-of-autoclave.composite.curing.and.bonding. 14 .Recent.technology.demon-
stration.programs.have.shown.potential.cost.savings.and.the.ability.to.make.