Environmental Engineering Reference
In-Depth Information
TABLE 6.9
Signiicance.of.the.Thermal.Stresses.on.Nose.Cap.
Manufacturing.From.Graphite.Epoxy.Composites
StressesActingintheRadialand
Tangential
Directions,
N/m
2
σ
11
*10
-5
Temperature,C
σ
22
*10
-5
20
2237.0
1611.6
17
2072.7
1493.0
14
1908.2
1374.6
12
1743.7
1256.0
9
1579.2
1137.6
The.signiicance.of.the.thermal.stresses.on.nose.cap.manufacturing.from.
graphite.epoxy.composites.is.listed.(Table.6.9).
For. carbon-carbon. composite,. the. coeficient. of. thermal. expansions. that.
were.in.the.radial.direction.is.α
11.
=.-5.45*10
-6
.m/m/°C.and.in.the.tangential.
direction.α
22.
=.-5.34*10
-6
.m/m/°C.
The.coeficient.of.thermal.expansion.in.an.arbitrary.direction.was.deter-
mined.as.α
12.
=.2sinα*cosα(α
11
-α
22
).
The. signiicance. of. the. thermal. stress. components
.
manufactured. from.
carbon-carbon.for.the.nose.cap
.
changed.when.the.gradient.of.temperature.
changed.from.-14°C.to.-17°C.for.the.compression.zone..Also,.the.same.is.true.
for.the.tension.zone.
Future.developments.of.NDE.methods.consist.of.the.elimination.of.ther-
mal.stresses.and.to.compare.with.strength.parameters.(see.Table 6.10).
The.failure. criteria. are. also. needed.for.design. and.for.guiding. materials.
improvement.
22
The.surface.of.the.equally.dangerous.biaxial.stress.conditions.for.graphite.
epoxy.composite.is.shown.in.Figure 6.5.
All.the.experimental.points.are.found.inside.this.surface,.and.for.the.nose.
cap. there. are. no. dangerous. conditions.. However,. if. thermal. stresses. reach.
a.threshold.of.failure,.the.nose.cap.can.collapse,.and.this.means.that.there.
TABLE 6.10
Parameters.of.Strength.For.Graphite.Epoxy.Composites,.Nm
2
Normal
Strength
Actingin
Diagonal
Directions,10
-5
Interlaminar
ShearStrength
*10
-5
Normal
Strength,*10
-5
InplaneShear
Strength*10
-5
Description
Signiicance
σ
11
,.σ
22
,.σ
33
τ
12
τ
13
σ
12
45
,.σ
13
45
,.σ
23
45
Compression.
zone
3448,827,.3448
34.4
68.9
2068,.2068,.3448
Tension.zone
6896,.1241,.34.4
34.4
68.9
4068,.827,.3620
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