Environmental Engineering Reference
In-Depth Information
infrared.camera.had.a.0.025
o
C.sensitivity.and.was.able.to.detect.anomalies,.
such.as.delaminations..The.inluence.of.the.velocity.of.curing.on.the.rise.of.
the.temperature.gradient.for.three.types.of.epoxy.resins.is.very.signiicant.
The.strength.of.composites.can.be.predicted.using.second.order.polynomi-
als.(Tsai.and.Wu,
17
.Wu,
18
.Hoffman,
19
.Hill
20
)..Strength.criteria.of.second.order.
is.not.capable.of.handling.air.stream.load,.particularly.for.strong.anisotropic.
materials.like.carbon/carbon.or.graphite.epoxy.
In.our.work,
21
.we.developed.a.strength.theory.and.found.the.strength.cri-
teria.in.tensor.form..This.criteria.can.be.used.separately.for.tensile.and.com-
pressive.loads.
The.probability.of.local.cracking.can.be.predicted.using.mathematical.models,.
which.include.the.irst.and.second.approach.in.the.law.of.normal.distribution.
1
-
t
2
2
1 2
P(t)
=
(6.28)
.
.
(
)
/
2
π
Here:
=
σ
-
S
σ
parameter.
t
bi
bm
j
σ
bi
.is.a.current.strength.in.x,y,z.direction;
σ
bm
.is.a.middle.strength.in.x,.y,.z.direction;
S
j
.is.a.sample.of.the.standard.deviation.for.each.environment.via:
n
j
1
∑
σ
(
)
2
2
.
S
=
-
σ
.
j
bi
bm
n
J
1
Here:.n
j
.is.a.number.of.test.samples.
We.calculated.the.middle.strength.σ
bm.
as:
n
j
=
∑
1
σ
σ
bm
bi
n
J
..
1
.
Thus,.for.a.single.test.condition.(such.as.compression.strength.in.the.iber.
direction),. the. data. were. collected. for. each. environment. being. tested.. The.
number.of.observations.in.each.environmental.condition.was.n
j
.where.j.sub-
script. represented. the. total. number. of. environments. being. pooled.. If. the.
assumption.of.normality.is.signiicantly.violated,.the.other.statistical.models.
should.be.investigated.to.it.the.data.
Search WWH ::
Custom Search