Dynamic Strength - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 145

1n 1 - P(t )

1

. N = . (5.81)

( )

1

L τ n - τ - nSj 1

bm bi

Here:
P(t 1 ). is. the. probability. structure. collapse. responsible. from. interlaminar.
shear.stress;
τ bi .is.the.current.shear.stress.acting.in.interlaminar.layers;
τ bm. is.the.middle.signiicant.shear.stress;
Sτ.is.the.middle.square.deviation.

Middle.square.deviation.can.be.found.using.Equation.(5.82):

1

( ) .

2

2

.. S τ = τ - τ (5.82)

bi bm

n - 1

Shear. strength. samples. molded. by. iberglass,. carbon. epoxy,. or. hybrid.
iberglass/carbon-tested.use.two.methods:.quad.lap.shear.test.(peel.test),.and.
tear.test.
Shear.strength.iber.compatibility.test.is.shown.in.Figure 5.6.
If.the.interlaminar.shear.strength.is.responsible.for.collapse.construction,.
fatigue.strength.can.be.predicted.as:

τ -1. =.τ s Φ(τ). (5.83)

Function.Φ(τ).is.shown.as:

Φ(τ).=.1.-.P(t 1 ). (5.84)

F

F

2

2

1

1

F

Quad lab shear test
1-First glass fiber layer
2-Second carbon fiber layer
shear strength test

Tear test

F

FIGURE 5.6
Shear.strength.test:.(1).irst.glass.iber.layer;.(2).second.carbon.iber.layer.