Environmental Engineering Reference
In-Depth Information
TABLE 6.1
The.elastic.constants.for.orthotropic.materials
1/E
z
-μ
yz
/E
y
-μ
xz
/E
x
0
0
0
-μ
zy
/E
x
1/E
y
-μ
xy
/E
x
-μ
zx
/E
z
-μ
yx
/E
y
1/E
x
1/G
zy
1/G
yx
1/G
xz
y,.and.x,.respectively;.G
zy
,.G
yx
,.and.G
xz
.are.the.modulus.of.shear.in.the.ply.
orientation.zy,.and.the.interlaminar.directions.are.zx.and.yx..μ
zy
,.μ
yx
,.and.μ
xz
.
are.the.Poisson's.ratios..The.irst.letter.in.the.subscript.of.μ.represents.direc-
tion.of.force.applied.and.the.second.letter.represents.the.transverse.direction.
of.E
45
,.is.the.Young.modulus.along.45°.in.the.plane.zy,.and.μ
45
.is.the.Poisson.
ratio.along.45°.orientation.
.
G
zy
=E
45
/2(1+μ
45
).
(6.1.1)
All.nine.parameters.can.be.predicted.using.the.ultrasonic.nondestruc-
tive. method.. This. method. is. based. on. the. measure. of. the. time. interval.
of. ultrasonic. oscillations. in. the. longitudinal. and. the. transverse. direc-
tions.. Gershberg
5
. used. semiconductors. of. model. YKC-1. to. measure. the.
time.interval..Semiconductors.YKC-1.are.provided.with.ultrasonic.heads.
having. frequencies. ranging. from. 20. to. 240. kHz.. To. maintain. acoustic.
contact.between.the.ultrasonic.heads,.the.blades,.and.the.blades'.surface,.
either.viscous.liquid.or.highly.viscous.oils.can.be.used.in.the.immersion.
medium.. The. acoustic. heads. are. installed. on. the. surface. of. the. blade. as.
shown.in.Figure 6.1..Along.the.longitudinal.direction,.a.wave.of.80.kHz.
was. used. to. measure. the. time. of. interval.. A. 100. mm. circle. diameter. is.
marked. on. the. surface. of. the. blade.. The. position. of. the. acoustic. heads.
is. varied. with. each. frequency. and. time. interval. of. measurement. (see.
Figure 6.1).
The. objective. is. to. ind. the. direction. in. which. the. ultrasonic. wave. can.
travel.in.a.minimum.of.time..The.velocity.of.the.ultrasonic.wave.can.be.cal-
culated.using.the.following.expression:
.
C=L/t.*.10
3
.
(6.2)
where:
C.is.the.velocity.of.the.ultrasonic.oscillations;
L.is.the.length.between.the.two.acoustic.heads;
t.is.the.time.taken.for.the.ultrasonic.oscillations.to.reach.from.one.head.to.
the.other.
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