NDE Digital Methods for Predicting Stiffness and Strength of Wind Turbine Blades - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 185

TABLE 6.15
Value.of.Technological.Parameters

Length
delaminating,
mm,C CracksNumber,n Parameter,C*n Strain, Δε 2 ,%

6 1 6 2.4

12 2 24 4.9

18 3 54 7.3

24 4 96 9.8

30 5 150 12.4

CORRELATION BETWEEN TEMPERATURE GRADIENT AND STRAIN PROPAGATION
700
600
500
400
300
200
100
0

Column A
Column B
Column C
Column D

1 2 3 4 5

STRAIN PROPAGATION IN DIFFERENT LAYERS, %

FIGURE 6.7
Measured.correlation.between.temperature.gradient.and.strain.propagation.

6.3.4 Fatigue Strength Improvement

Figure 6.8.shows.the.simultaneous.injection.of.a.healing.agent.and.catalyst.
into.the.test.package.during.stress.testing..Injection.occurred.when.a.temper-
ature.gauge.indicated.to.the.injection.pumps.when.the.surface.temperature.
of.the.package.increased..The.healing.agent.and.solid.catalyst.are.dispersed.
irst. 27 .Valves.control.the.four.pumps.indicate.in.Figure 6.8.

6.3.5 Conclusions

. 1.. Laser.light,.detected.by.imbedded.sensors,.is.a.good.measure.of.the.

formation.of.delaminating.cracks.during.fatigue.testing.

. 2.. An.infrared.radiation.camera.accurately.measures.the.surface.tem-

perature.of.test.objects.during.fatigue.testing.

. 3.. Surface.temperature.is.a.good.predictor.of.fatigue.strength.as.mea-

sured.by.fatigue.testing.

. 4.. Injecting. a. healing. agent. and. a. solid. catalyst. can. increase. fatigue.

strength.by.up.to.30.percent.