Dynamic Strength - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 123

2

1
r

d
dr

Φ 1

r

d
d

Φ

σ = × + × - Fz(r, ∫ θ )

r

2

θ

2

2

d
dr

Φ

σ θ = - Fy(r ∫ , θ )

. . .(5.13)

2

2

1
r

d
d

Φ

- 1
r

d
drd

Φ d

dr

1 d

d

Φ

τ = × × = ×

r θ

2

θ θ r θ

The.stress.function.Φ.seen.in.Chou.and.Pagano 6 .can.be.found.as.Equation.
(5.14):

. Φ=.M.Ψ. (5.14)

Here,. coeficient. M. has. a. constant. value. and. Ψ. is. a. geometrical. proile.
function.
In.Golfman, 7 .the.aviation.proile.Ψ.is.represented.by.Equation.(5.15).

.. λx 2 .-k(y-α).(y-β).=.0. (5.15)

The.coeficient.of.proile.K.can.be.found.as:

2

27
16

λ
α β .

e

k

K =

-

. (5.16)

where:
e k. is.a.maximum.length.of.proile;
α.is.a.distance.from.exit.x.to.exit.edge;
β.is.a.distance.from.exit.x.to.entry.edge;
λ.is.the.coeficient.of.anisotropy.

Therefore,

G
G

yz

λ =

. .represents.the.equation.for.the.skin.layers;. (5.17)

xz

G yz ,.G xz .=.modulus.of.shear.in.xz,.yz.interlaminar.directions.
For. a. composite. carbon/iber. epoxy. sandwich. structure,. the. modulus. of.
shear.can.be.determined.as.Equation.(5.18).

s h

G + G
G + G

xz yz

λ =

.

h .

(5.18)

s

xz yz