Dynamic Strength - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 120

The. history. of. the. manufacturing. process. is. very. signiicant. because. it.
relates.how.the.coniguration.and.architecture.of.design.was.determined..A.
new.chapter.in.aviation.history.opened.in.2003.with.the.maiden.light.of.the.
world's. irst. civil. tilt. rotor,. the. Bell/Augusta. Aerospace. BA609. 3 . The. rotors.
were.installed.in.the.vertical.position.and.hovered.at.an.altitude.of.50.feet,.
performed.left.and.right.peddle.turns,.both.forward.and.aft.light.maneu-
vers.and.four.take-off.and.landings..When.the.rotors.are.tilted.forward.in.
the.horizontal.position,.the.aircraft.is.able.to.ly.as.a.turboprop.ixed-wing.
airplane..The.transition.from.helicopter.mode.to.airplane.mode.takes.2.sec,.
as.does.the.transition.from.airplane.mode.to.helicopter.mode..For.the.design.
and. manufacturing. of. the. prototype. YUH-60A. UTTAS. tail. rotor,. the. pul-
trusion.process 4. was.selected..Fully.cured.pultruded.spar.design.layout.and.
manufacturing. approach. was. developed.. This. is. important. since. the. pul-
truded.spar.consists.of.the.two.blades.being.manufactured.simultaneously..
Elastic.coupling,.which.has.a.signiicant.effect.on.the.dynamic.elastic.torsion.
response.of.the.rotor,.was.reported.by.E..C..Smith. 5
We.have.assumed.that.the.propeller.blade,.as.presented.in.Figure 5.1,.is.a.
curved. plate. with. variable. thickness. and. forces. acting. on. it.. Acting. forces.
include:.air.stream.load,.rotating.forces,.and.bending.and.torsion.moments..I.
have.assumed.that.the.blade.rotates.about.the.Z.axis,.with.a.constant.angular.
velocity. ω. (see. Figure 5.1).. We. have. X,. Y,. and. Z. Cartesian. coordinates. and.
polar.coordinates.R,.θ,.and.Z.
In.Figure 5.1,.we.see.a.cut.through.the.equilibrium.element.of.a.rotor.blade.
and.the.normal.and.shear.stress.distribution.in.the.top.section.
Here,. Fz. is. axial. force,. Fx,. Fy. are. tangential. forces. and. Mz,. My,. Mx. are.
rotating.moments.relative.to.axes.Z,.Y,.X..The.area.of.cross.section.is.denoted.

Fz Mz

Fx

My
Fy A

z

Mx
Cross-section
A-A

x

A

o

R

y

R,O,Z-Current polar coordinates
X,Y,Z-Current cartesian coordinates

Wind turbine rotor blades

FIGURE 5.1
Wind.turbine.rotor.blades.