Dynamic Strength - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 146

Here:.P(t 1 ).is.the.probability.of.collapse.of.the.local.part.of.construction.from.
the.interlaminar.shear.strength.

τ -

S

τ
τ

bi bm

Parameter τ

1 =

. (5.85)

The.Weibull.distribution.function.is.shown.as.the.example.of.the.Laplace.
function.. The. Laplacian. transformation. is. a. powerful. method. for. solving.
linear. differential. equations. arising. in. engineering. mathematics. 35 . Thus,.
we.designate:

− bt

. P(t) = L(t ) =

0

e f(t)dt . (5.86)

The.function.L(t).is.called.the.Laplacian.transform.of.the.original.function.
f(t).. Furthermore,. the. original. function. f(t). is. called. the. inverse. transform.
function.and.will.be.denoted.by.L -1. (F),.that.is:

. f(t).=.L -1. (F).. (5.87)

2 2 0

1 t - t

(2p)

L(e) = e

. . (5.88) 1/2

Function.L(e . ).is.a.two.parameter.function.that.represents.the.law.of.normal.
distribution.function.and.the.prediction.probability.with.variation.strength.
parameters.σ bi. .

5.8.3 Static and Dynamic Fatigue Strength

Reinforced.iberglass.or.carbon/epoxy.are.very.sensitive.to.the.equal.static.
load. repeatedly. applied. in. a. long. period. of. time,. which. is. why. it. is. called.
static fatigue of the material.
The.limit.of.fatigue.for.graphite/epoxy.on.the.base.of.1,000.cycles.equals.
0.6.to.0.7.from.the.limit.of.the.static.strength..Bending.does.not.increase.due.
to.beneicial.elastic.properties..Loops.of.hysteresis.from.loading.and.unload-
ing.are.practically.identical..Residue.of.deformation.accumulated.after.test-
ing.samples.for.1,000.cycles.have.no.signiicant.value..Dynamic.testing.has.
the.support.signiicance.of.internal.heat.
Internal. heat. depends. on. harmonic. frequencies. and. the. amplitude. of.
vibration,.and.the.heat.of.the.composites.is.connected.with.hysteresis.losses..
The.quantity.of.heat.is.increased.when.there.is.an.increase.in.frequency.of.