Materials for Turbine Power Blades, Reinforcements, and Resins - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 58

TABLE 3.1
Mechanical.Properties.of.Carbon.Fiber.and.Glass.Fiber.Impregnated.by.Epoxy.and.
Liquid.Polymer.Resins

Designationpsi
(MPA)

CarbonFiber
IM7+Epoxy 1162U 43741 1166N

Tensile.strength 440,000.(3,036) 235,000.(1,62) 254,000.(1,75) 254,000.(1,75)

Tensile.modules 25,5.´.10 6.

(1,76.GPA)

15,6.´.10 6 6,8.´.10 6 .

(0.47.GPA)

16,8.´.10 6 .(1,16.
GPA)

Compression.
strength

136,000.(0.938.
GPA)

161,000.
(1,11.GPA)

76,900
(0,536.GPA)

Compression.
modulus

14,7´.10 6 6,6.´.10 6. .(0.46.

GPA)

7,4.´.10 6.
(0,51.GPA)

Flexural.strength 240,000.(1,655) 227,000.(1,565) 223,000.(1,54) 230,000.(1,586)

Flexural.
modulus

21,5.´.10 6 .(1,48.
GPA)

16,2.´.10 6 6,5.´.10 6 .

(0,45.GPA)

19,1.´.10 6. (1,31.
GPA)

Short.beam.shear.
strength

18,500.
(1,28)

12,500.
(0,86)

12,500.
(0,86)

12,500.
(0,86)

Resins,.such.as.epoxy.or.vinyl/polyester,.have.demonstrated.a.capacity.for.
long. life.. Thermoplastic. liquid. resins,. such. as. polyphenylene. sulide. (PPS).
and.polyetheretherketone.(PEEK),.also.are.used.for.inner.web-cap.spars.
The.basic.commercial.parameters.for.selecting.resins.material.properties.
are.their.viscosity.and.curing.time..A.practical.study.of.material.response.is.
irst.investigating.the.material's.viscosity. 2
Viscosity. is. the. measurement. of. a. luid's. resistance. to. low.. For. a. liquid.
under. shear,. the. rate. of. deformation. (or. shear. rate). is. proportional. to. the.
shearing.stress..Newton's.law.states.that.the.ratio.of.the.stress.to.the.shear.
rate.is.a.constant..That.constant.is.viscosity. 3 .The.common.units.for.viscos-
ity.are.poise.(P),.grams.per.centimeter.second.g/(cm.s),.or.dyne.seconds.per.
square.centimeter.(dyn.s)/cm 2 )..The.centipoise.(cP),.one.hundredth.of.a.poise,.
is.the.most.common.unit..The.SI.units.of.viscosity.is.Pascal.seconds.(Pa.s.and.
mPa.s)(1.mPa.s.=.1.cP). 4,5
The.viscosity.of.most.materials.decreases.as.temperature.increases.
The.Andrade.equation.relates.the.viscosity.to.temperature.as.follows:

. h.=.A.10B/T.. (3.2)

. log.η.=.logA.+.B/T... (3.3)

where:
A.and.B.are.constants.characteristic.of.the.polymer.or.other.material;
T.is.the.absolute.temperature.

The. viscosity. of. a. polymer. at. a. given. temperature. can. be. estimated. by.
knowing. the. viscosity. of. two. other. temperatures.. This. knowledge. allows.