Condition Assessment of Kevlar Condition Assessment of Kevlar Composite Materials Using Raman Composite Materials Using Raman Spectroscopy Spectroscopy Glenn Washer Glenn Washer Thomas Brooks Thomas Brooks Civil & Civil & Environmental Environmental Engineering Department Engineering Department University of Missouri University of Missouri – – Columbia Columbia https://ntrs.nasa.gov/search.jsp?R=20070032686 2020-03-27T04:31:38+00:00Z
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Con
ditio
n A
sses
smen
t of K
evla
r C
ondi
tion
Ass
essm
ent o
f Kev
lar
Com
posi
te M
ater
ials
Usi
ng R
aman
C
ompo
site
Mat
eria
ls U
sing
Ram
an
Spec
trosc
opy
Spec
trosc
opy
Gle
nn W
ashe
rG
lenn
Was
her
Thom
as B
rook
sTh
omas
Bro
oks
Civ
il &
C
ivil
& E
nviro
nmen
tal
Envi
ronm
enta
l Eng
inee
ring
Dep
artm
ent
Engi
neer
ing
Dep
artm
ent
Uni
vers
ity o
f Mis
sour
i U
nive
rsity
of M
isso
uri ––
Col
umbi
aC
olum
bia
https://ntrs.nasa.gov/search.jsp?R=20070032686 2020-03-27T04:31:38+00:00Z
Ove
rvie
wO
verv
iew
••G
oals
& O
bjec
tives
Goa
ls &
Obj
ectiv
es••
Hyp
othe
sis
Hyp
othe
sis
••K
evla
r Com
posi
te M
ater
ial
Kev
lar C
ompo
site
Mat
eria
l••
Ram
an S
pect
rosc
opy
Ram
an S
pect
rosc
opy
••R
evie
w o
f Lite
ratu
reR
evie
w o
f Lite
ratu
re••
Expe
rimen
tal
Expe
rimen
tal
••R
esul
ts &
Dis
cuss
ion
Res
ults
& D
iscu
ssio
n••
Con
clus
ions
Con
clus
ions
Goa
ls a
nd O
bjec
tives
Goa
ls a
nd O
bjec
tives
••G
oal:
To e
valu
ate
Ram
an sp
ectro
scop
y as
a
Goa
l: To
eva
luat
e R
aman
spec
trosc
opy
as a
po
tent
ial N
DE
tool
for t
he d
etec
tion
of
pote
ntia
l ND
E to
ol fo
r the
det
ectio
n of
st
ress
rupt
ure
in K
evla
r. st
ress
rupt
ure
in K
evla
r.
••O
bjec
tive:
Tes
t a se
ries o
f stra
nd sa
mpl
es
Obj
ectiv
e: T
est a
serie
s of s
trand
sam
ples
th
at h
ave
been
age
d un
der v
ario
us
that
hav
e be
en a
ged
unde
r var
ious
co
nditi
ons a
nd e
valu
ate
diff
eren
ces a
nd
cond
ition
s and
eva
luat
e di
ffer
ence
s and
tre
nds i
n th
e R
aman
resp
onse
tre
nds i
n th
e R
aman
resp
onse
Hyp
othe
sis
Hyp
othe
sis
••R
educ
tion
in st
reng
th a
ssoc
iate
d w
ith st
ress
R
educ
tion
in st
reng
th a
ssoc
iate
d w
ith st
ress
ru
ptur
e m
ay m
anife
st fr
om c
hang
es in
the
rupt
ure
may
man
ifest
from
cha
nges
in th
e po
lym
er a
t a m
olec
ular
leve
l. If
so, t
han
poly
mer
at a
mol
ecul
ar le
vel.
If so
, tha
n th
ese
chan
ges m
ay e
ffec
t the
th
ese
chan
ges m
ay e
ffec
t the
vib
ratio
nal
vibr
atio
nal
char
acte
ristic
s of t
he m
ater
ial,
and
char
acte
ristic
s of t
he m
ater
ial,
and
cons
eque
ntly
the
Ram
an sp
ectra
pro
duce
d co
nseq
uent
ly th
e R
aman
spec
tra p
rodu
ced
from
the
mat
eria
l fr
om th
e m
ater
ial
Prob
lem
Sta
tem
ent
Prob
lem
Sta
tem
ent
••K
evla
r com
posi
te o
ver
Kev
lar c
ompo
site
ove
r --w
rapp
ed p
ress
ure
wra
pped
pre
ssur
e ve
ssel
s (ve
ssel
s (C
OPV
sC
OPV
s ) o
n th
e sp
ace
shut
tles a
re
) on
the
spac
e sh
uttle
s are
gr
eate
r tha
n 25
yea
rs o
ldgr
eate
r tha
n 25
yea
rs o
ld••
Stre
ss ru
ptur
e ph
enom
ena
is n
ot w
ell
Stre
ss ru
ptur
e ph
enom
ena
is n
ot w
ell
unde
rsto
od fo
r un
ders
tood
for C
OPV
sC
OPV
s••
Oth
er
Oth
er C
OPV
sC
OPV
sar
e pl
anne
d fo
r hyd
roge
nar
e pl
anne
d fo
r hyd
roge
n --fu
eled
fu
eled
ve
hicl
es u
sing
Car
bon
com
posi
te m
ater
ial
vehi
cles
usi
ng C
arbo
n co
mpo
site
mat
eria
l
CO
PVso
n Sh
uttle
Orb
iter
Kev
lar y
arn
Kev
lar/e
poxy
com
posi
te st
rand
CO
PVso
n Sh
uttle
Orb
iter
•Com
posi
tes u
sed
prim
arily
for t
he h
igh
stre
ngth
-to-w
eigh
t rat
io
Stre
ss R
uptu
re P
heno
men
aSt
ress
Rup
ture
Phe
nom
ena
••M
ater
ial u
nder
con
stan
t loa
d ov
er lo
ng p
erio
ds o
f M
ater
ial u
nder
con
stan
t loa
d ov
er lo
ng p
erio
ds o
f tim
e fa
ils w
ithou
t an
incr
ease
in th
e lo
adtim
e fa
ils w
ithou
t an
incr
ease
in th
e lo
ad••
Fibe
rs a
re st
rain
ed a
t a m
olec
ular
leve
l unt
il ru
ptur
e Fi
bers
are
stra
ined
at a
mol
ecul
ar le
vel u
ntil
rupt
ure
with
ass
ocia
ted
cree
p (e
xact
mec
hani
sm o
f mat
eria
l w
ith a
ssoc
iate
d cr
eep
(exa
ct m
echa
nism
of m
ater
ial
wea
keni
ng is
not
kno
wn)
wea
keni
ng is
not
kno
wn)
••C
urre
ntly
ther
e is
no
know
n m
etho
d to
det
ect s
tress
C
urre
ntly
ther
e is
no
know
n m
etho
d to
det
ect s
tress
ru
ptur
e by
non
dest
ruct
ive
mea
nsru
ptur
e by
non
dest
ruct
ive
mea
ns••
Ram
an sp
ectro
scop
y m
ay b
e a
solu
tion
to th
is
Ram
an sp
ectro
scop
y m
ay b
e a
solu
tion
to th
is
prob
lem
prob
lem
Fibe
r Fai
lure
Fibe
r Fai
lure
••In
fibe
r com
posi
te m
ater
ial,
once
a fi
ber
In fi
ber c
ompo
site
mat
eria
l, on
ce a
fibe
r fa
ils th
e st
ress
is tr
ansf
erre
d to
the
adja
cent
fa
ils th
e st
ress
is tr
ansf
erre
d to
the
adja
cent
fib
ers
fiber
s––
This
can
star
t a c
hain
reac
tion
that
end
s in
a Th
is c
an st
art a
cha
in re
actio
n th
at e
nds i
n a
cata
stro
phic
failu
re o
f the
ent
ire c
ompo
site
cata
stro
phic
failu
re o
f the
ent
ire c
ompo
site
••Lo
cal v
aria
tions
in th
e st
ate
of st
ress
/stra
inLo
cal v
aria
tions
in th
e st
ate
of st
ress
/stra
in
••St
rain
ass
ocia
ted
with
cre
ep m
ay m
odify
the
Stra
in a
ssoc
iate
d w
ith c
reep
may
mod
ify th
e R
aman
spec
tra o
f a fi
ber
Ram
an sp
ectra
of a
fibe
r
••Fi
bers
may
als
o de
grad
e by
cha
in sc
issi
onFi
bers
may
als
o de
grad
e by
cha
in sc
issi
on––
Bre
akin
g of
B
reak
ing
of in
tera
tom
icin
tera
tom
icbo
nds
bond
s––
Res
ultin
g in
cha
nges
in
Res
ultin
g in
cha
nges
in v
ibra
tiona
lvi
brat
iona
lch
arac
teris
tics
char
acte
ristic
s
Fibe
r Fai
lure
Fibe
r Fai
lure
•Gen
eral
loss
of o
rder
in th
e K
evla
r pol
ymer
–ch
ain
cros
s-lin
king
–– Res
ultin
g in
cha
nges
in
Res
ultin
g in
cha
nges
in v
ibra
tiona
lvi
brat
iona
l cha
ract
eris
tics
char
acte
ristic
s
Ram
an S
pect
rosc
opy
Ram
an S
pect
rosc
opy
••La
ser t
echn
ique
that
is se
nsiti
ve to
La
ser t
echn
ique
that
is se
nsiti
ve to
m
olec
ular
inte
ract
ions
in m
ater
ials
such
as
mol
ecul
ar in
tera
ctio
ns in
mat
eria
ls su
ch a
s K
evla
r, gr
aphi
te a
nd c
arbo
nK
evla
r, gr
aphi
te a
nd c
arbo
n••
Mea
sure
s cha
nges
in fr
eque
ncy
Mea
sure
s cha
nges
in fr
eque
ncy
(wav
elen
gth)
resu
lting
from
inel
astic
(w
avel
engt
h) re
sulti
ng fr
om in
elas
tic
scat
terin
g pr
oces
ses
scat
terin
g pr
oces
ses
Scat
tere
d Li
ght
••R
ayle
igh
scat
tere
d lig
ht (e
last
ic)
Ray
leig
h sc
atte
red
light
(ela
stic
)••
Ram
an sc
atte
red
light
(ine
last
ic)
Ram
an sc
atte
red
light
(ine
last
ic)
Ram
an M
olec
ular
Inte
ract
ion
Ram
an S
pect
rosc
opy
Ram
an S
pect
rosc
opy
••Th
e sh
ifts i
n fr
eque
ncy
of th
e in
cide
nt li
ght r
elat
es
The
shift
s in
freq
uenc
y of
the
inci
dent
ligh
t rel
ates
to
the
to th
e vi
brat
iona
lvi
brat
iona
l pro
perti
es o
f the
mol
ecul
epr
oper
ties o
f the
mol
ecul
e––
Vib
ratio
nal
Vib
ratio
nal m
odes
of a
mol
ecul
e ca
n be
mod
eled
and
m
odes
of a
mol
ecul
e ca
n be
mod
eled
and
R
aman
scat
terin
g pr
edic
ted
Ram
an sc
atte
ring
pred
icte
d ••
Pola
rizab
ility
Pola
rizab
ility
of th
e m
olec
ule
of th
e m
olec
ule
••In
tera
tom
icIn
tera
tom
icfo
rces
bet
wee
n at
oms
forc
es b
etw
een
atom
s––
Peak
shift
s dep
end
on
Peak
shift
s dep
end
on
••St
rain
Stra
in••
Cry
stal
linity
Cry
stal
linity
••M
olec
ular
stru
ctur
eM
olec
ular
stru
ctur
e••
Tem
pera
ture
Tem
pera
ture
Vib
ratio
nal
Vib
ratio
nal m
odes
ass
ocia
ted
with
m
odes
ass
ocia
ted
with
pe
aks f
ound
in th
e R
aman
spec
tra
peak
s fou
nd in
the
Ram
an sp
ectra
Fr
eque
ncy
/ cm
-1
Assi
gnm
ent
630,
732
, 786
rin
g vi
brat
ions
84
5 C
-H o
ut-o
f-pla
ne b
endi
ng
863
ring
vibr
atio
ns
1103
C
-H in
-pla
ne b
endi
ng
1181
, 127
7, 1
327,
151
4 C
-C ri
ng s
tretc
hing
13
18
C-H
in-p
lane
ben
ding
15
69
amid
e II
(60%
N-H
ben
ding
; 40%
C-N
stre
tchi
ng
1610
C
-C ri
ng s
tretc
hing
1648
am
ide
I (80
% C
=O s
tretc
hing
; 10%
C-N
st
retc
hing
10%
N-H
ben
ding
) B
. H. S
tuar
t, Po
lym
er B
ulle
tin 3
5,72
7-73
3 (1
995)
4000
0
5000
0
6000
0
7000
0
8000
0
9000
0
1000
00
1100
00
1200
00
600
800
1000
1200
1400
1600
1800
WAV
ENU
MB
ER (c
m-1
)
RELATIVE INTENSITY (counts/sec) 16
13 c
m-1
1649
cm
-1
Che
mic
al S
truct
ure
of K
evla
r
Kev
lar A
ram
idFi
ber
Kaw
agoe
et a
l. (1
999)
Peak
shift
(~16
13 c
mPe
ak sh
ift (~
1613
cm
-- 11) W
ith S
tress
) With
Stre
ss
Scha
dler
et a
l. (1
995)
Rev
iew
of L
itera
ture
Rev
iew
of L
itera
ture
Scha
dler
et a
l. (1
995)
•As a
mat
eria
l is s
train
ed, t
he in
tera
tom
icdi
stan
ce c
hang
es re
sulti
ng in
a c
hang
e in
the
inte
rato
mic
forc
e, a
nd th
us a
cha
nge
in th
e vi
brat
iona
lfre
quen
cy•
The
~161
3 cm
-1pe
ak e
xhib
its th
e hi
ghes
tse
nsiti
vity
with
stre
ss/s
train
Pras
ad e
t al.
(199
0)•R
aman
ban
d br
oade
ning
due
to d
efec
ts in
th
e m
olec
ular
cha
in
•Def
ects
pos
sibl
y fr
om st
ress
or h
arsh
en
viro
nmen
tal c
ondi
tions
Stua
rt (1
995)
•Use
d a
1064
nm
inci
dent
lase
r to
inve
stig
ate
wat
er a
bsor
ptio
n in
Kev
lar
•Fou
nd a
dec
reas
e in
inte
nsity
for t
he 1
613
cm-1
Ram
an b
and
Expe
rimen
tal
Expe
rimen
tal
••R
enis
haw
Ren
isha
wR
aman
R
aman
inV
iain
Via
spec
trom
eter
spec
trom
eter
••FT
Ram
an sy
stem
FT R
aman
syst
em
•Typ
ical
Mic
ro-R
aman
Spe
ctro
met
er
Spec
tra fr
om K
evla
r with
inci
dent
lase
r Sp
ectra
from
Kev
lar w
ith in
cide
nt la
ser
wav
elen
gths
of 6
47, 7
52 a
nd 1
064
nmw
avel
engt
hs o
f 647
, 752
and
106
4 nm
0
2000
00
4000
00
6000
00
8000
00
1000
000
1200
000
1400
000
1600
000
1800
000
2000
000 60
080
010
0012
0014
0016
0018
00W
AVE
NU
MB
ER (c
m-1
)
RELATIVE INTENSITY
01000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
8000
0
1064
nm
647
nm
752
nm
Spec
tra fr
om K
evla
r with
Inci
dent
lase
r Sp
ectra
from
Kev
lar w
ith In
cide
nt la
ser
wav
elen
gths
of 4
88 n
mw
avel
engt
hs o
f 488
nm
0
5000
0
1000
00
1500
00
2000
00
2500
00
3000
00 600
800
1000
1200
1400
1600
1800
WA
VEN
UM
BER
(cm
-1)
RELATIVE INTENSITY
488
nm la
ser
0
5000
0
1000
00
1500
00
2000
00
2500
00
3000
00
3500
00 600
800
1000
1200
1400
1600
1800
WAV
ENU
MB
ER (c
m-1
)
RELATIVE INTENSITY (counts/sec)
90°0°
90°
0°Fi
ber
Alig
nmen
t
Com
paris
on o
f Ram
an P
eaks
for
Com
paris
on o
f Ram
an P
eaks
for
Kev
lar
Kev
lar
Penn
, L.,
Mila
novi
ch, F
., Ra
man
Spe
ctro
scop
y of
Kev
lar 4
9 Fi
ber.
Poly
mer
, 197
9. 2
0(1)
: p. 3
1-36
.
Kim
, P.K
., C
hang
, C.,
Hsu
, S.L
., N
orm
al V
ibra
tiona
lAna
lysi
s of a
Rig
id R
od P
olym
er: p
oly(
p-ph
enyl
ene
tere
phth
alam
ide)
.Pol
ymer
, 198
6. 2
7(1)
: p. 3
4-46
.
Kev
lar y
arn
Kev
lar y
arn
vsvsco
mpo
site
stra
ndco
mpo
site
stra
nd
0
5000
0
1000
00
1500
00
2000
00
2500
00
3000
00
3500
00
4000
00
4500
00
600
800
1000
1200
1400
1600
WAV
ENUM
BER
(cm
-1)
RELATIVE INTENSITY (counts/sec)
Kevla
r/epo
xy s
trand
Kevla
r yar
n
Stra
nd S
ampl
es
Stra
nd S
ampl
es
XX
Step
ped
isot
herm
al s
trand
s; 1
4o5,
21o
5,
23d5
, 23o
5SI
M K
evla
r Str
ands
XX
4560
den
ier,
cure
d an
d un
cure
dA
TK K
evla
r pre
preg
XX
XSN
032,
pre
ssur
e 50
% ~
4200
psi
Flee
t Lea
der T
ank
SN03
2
XX
S/N
007
, 50%
pre
ssur
e ~
4200
psi
Flee
t Lea
der T
ank
SN00
7
XX
X65
% u
ltst
reng
th (6
5 lb
s) a
t diff
eren
t tim
es
and
tem
pera
ture
sTR
I Cre
ep T
est S
ampl
es
XX
orig
inal
virg
in y
arn,
142
0 de
nier
TRI V
irgin
Kev
lar 4
9 Ya
rn
XX
Xor
igin
al v
irgin
stra
nds,
114
0 de
nier
TRI V
irgin
Kev
lar 4
9 St
rand
s
1064
nm
752
nm64
7 nm
488
nmN
otes
Sam
ple
Type
Stra
nd S
peci
men
s St
rand
Spe
cim
ens
yes
761
2F12
yes
929
2F11
yes
904
2F10
yes
901
2F9
room
0Vi
rgin
yes
929
2F1
Faile
d?Te
mp
(°C
)A
ged
(hrs
)Sp
ecim
en
TRI C
reep
Str
ands
SIM
Stra
nds
Full
wid
th a
t hal
f max
imum
(F
WH
M) r
atio
Inte
nsity
ratio
4000
0
5000
0
6000
0
7000
0
8000
0
9000
0
0000
0
1000
0
2000
0 600
800
1000
1200
1400
1600
1800
WAV
ENU
MB
ER (c
m-1
)
RELATIVE INTENSITY (counts/sec)
~161
3 cm
-1
~164
9 cm
-1~1
278
cm-1
1278
II ii=
χ12
78FW
HM
FWH
Mi
i=
η
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
cmIn
tens
ity V
aria
tions
(rel
ativ
e to
127
8 cm
-- 11) f
or V
irgin
Stra
nds,
) for
Virg
in S
trand
s, 64
7 nm
inci
dent
wav
elen
gth
647
nm in
cide
nt w
avel
engt
h
Var
iatio
ns in
the
inte
nsity
of d
iffer
ent v
irgin
mat
eria
ls
stde
v: 0
.10
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
cmcm-- 11) f
or
) for
V
irgin
Stra
nds
Virg
in S
trand
s vsvs
SIM
spec
imen
s, 64
7 nm
SIM
spec
imen
s, 64
7 nm
stde
v: 0
.09
VIR
GIN
14o5
21o5
23d5
23o5
VIR
GIN
_hig
h
VIR
GIN
_low
23d5
_hig
h
23d5
_low
1613
cm
-1 b
and
VIR
GIN
23
d5
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
cmcm-- 11) f
or
) for
V
irgin
Stra
nds
Virg
in S
trand
s vsvs
SIM
spec
imen
s, 64
7 nm
SIM
spec
imen
s, 64
7 nm
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
cmIn
tens
ity V
aria
tions
(rel
ativ
e to
127
8 cm
-- 11) f
or V
irgin
Stra
nds
) for
Virg
in S
trand
s vsvs
Flee
t Lea
der s
peci
men
s, 64
7 nm
inci
dent
wav
elen
gth
Flee
t Lea
der s
peci
men
s, 64
7 nm
inci
dent
wav
elen
gth
stde
v: 0
.08
VIR
GIN
SN00
7aSN
007b
SN03
2aSN
032b
VIR
GIN
_hig
hV
IRG
IN_l
owSN
032a
_hig
hSN
032a
_low
1613
cm
-1ba
nd
VIR
GIN
SN
032a
Inte
nsity
Var
iatio
ns (r
elat
ive
to 1
278
cmIn
tens
ity V
aria
tions
(rel
ativ
e to
127
8 cm
-- 11) f
or V
irgin
Stra
nds
) for
Virg
in S
trand
s vsvs
Flee
t Lea
der s
peci
men
s, 64
7 nm
inci
dent
wav
elen
gth
Flee
t Lea
der s
peci
men
s, 64
7 nm
inci
dent
wav
elen
gth
FWH
M (r
elat
ive
to 1
278
cmFW
HM
(rel
ativ
e to
127
8 cm
-- 11) f
or V
irgin
Stra
nds
) for
Virg
in S
trand
s vsvs
Flee
t Fl
eet
Lead
er sp
ecim
ens,
647
nm in
cide
nt w
avel
engt
hLe
ader
spec
imen
s, 64
7 nm
inci
dent
wav
elen
gth
stde
v: 0
.04
VIR
GIN
SN00
7aSN
007b
SN03
2aSN
032b
VIR
GIN
_hig
hV
IRG
IN_l
owSN
032a
_hig
hSN
032a
_low
1613
cm
-1 b
and
VIR
GIN
SN03
2a
FWH
M (r
elat
ive
to 1
278
cmFW
HM
(rel
ativ
e to
127
8 cm
-- 11) f
or V
irgin
Stra
nds
) for
Virg
in S
trand
s vsvs
Flee
t Fl
eet
Lead
er sp
ecim
ens,
647
nm in
cide
nt w
avel
engt
hLe
ader
spec
imen
s, 64
7 nm
inci
dent
wav
elen
gth
FT R
esul
ts
FT R
esul
ts ––
Flee
t Lea
der
Flee
t Lea
der
Peak
shift
s for
all
stra
nd sp
ecim
ens
Peak
shift
s for
all
stra
nd sp
ecim
ens
1613
cm
1613
cm
-- 11Pe
ak S
hift
with
Pe
ak S
hift
with
A
pplie
d Fo
rce,
647
nm
App
lied
Forc
e, 6
47 n
m
y =
-0.1
472x
+ 1
612.
5
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
010
2030
4050
60FO
RC
E (l
bs)
PEAK POSTION (cm-1
)
Che
mic
al S
truct
ure
of K
evla
r
Def
ects
in m
olec
ular
str
uctu
re-p
erha
ps fo
r hyd
roge
n bo
nds
~161
3 cm
-1
Fibe
r Opt
ic R
aman
Sys
tem
sFi
ber O
ptic
Ram
an S
yste
ms
The
lase
r bea
m is
dire
cted
thro
ugh
a fib
er o
ptic
pro
be
whi
ch c
an b
e ta
ken
out i
n th
e fie
ld fo
r mea
sure
men
ts
Ren
isha
wA
valo
n In
st.
Sum
mar
ySu
mm
ary
••R
aman
spec
trosc
opy
is b
eing
exp
lore
d as
an
ND
E R
aman
spec
trosc
opy
is b
eing
exp
lore
d as
an
ND
E te
chni
que
to p
redi
ct th
e on
set o
f stre
ss ru
ptur
e in
te
chni
que
to p
redi
ct th
e on
set o
f stre
ss ru
ptur
e in
K
evla
r com
posi
te m
ater
ials
Kev
lar c
ompo
site
mat
eria
ls••
Test
age
d K
evla
r stra
nds t
o di
scov
er tr
ends
in th
e Te
st a
ged
Kev
lar s
trand
s to
disc
over
tren
ds in
the
Ram
an re
spon
seR
aman
resp
onse
••St
reng
th re
duct
ion
in K
evla
r pol
ymer
will
St
reng
th re
duct
ion
in K
evla
r pol
ymer
will
m
anife
st it
self
on th
e R
aman
spec
tra
man
ifest
itse
lf on
the
Ram
an sp
ectra
Con
clus
ions
Con
clus
ions
Ram
an sp
ectro
scop
y ha
s sho
wn
Ram
an sp
ectro
scop
y ha
s sho
wn
––R
elat
ive
chan
ges i
n th
e in
tens
ity a
nd F
WH
M o
f the
~16
13
Rel
ativ
e ch
ange
s in
the
inte
nsity
and
FW
HM
of t
he ~
1613
cmcm
-- 11pe
akpe
ak••
Red
uctio
n in
rela
tive
inte
nsity
for c
reep
, fle
et le
ader
, and
SIM
Red
uctio
n in
rela
tive
inte
nsity
for c
reep
, fle
et le
ader
, and
SIM
spec
imen
s com
pare
d to
the
virg
in st
rand
s sp
ecim
ens c
ompa
red
to th
e vi
rgin
stra
nds
••In
crea
se in
FW
HM
has
bee
n ob
serv
ed fo
r the
cre
ep a
nd fl
eet
Incr
ease
in F
WH
M h
as b
een
obse
rved
for t
he c
reep
and
flee
t le
ader
spec
imen
s com
pare
d to
the
virg
in st
rand
s le
ader
spec
imen
s com
pare
d to
the
virg
in st
rand
s ••
Cha
nges
in th
e R
aman
spec
tra m
ay re
sult
from
redi
strib
utin
g C
hang
es in
the
Ram
an sp
ectra
may
resu
lt fr
om re
dist
ribut
ing
load
s with
in th
e m
ater
ial d
ue to
the
disr
uptio
n of
hyd
roge
n lo
ads w
ithin
the
mat
eria
l due
to th
e di
srup
tion
of h
ydro
gen
bond
ing
betw
een
crys
talli
tes o
r def
ects
in th
e cr
ysta
llite
s fro
mbo
ndin
g be
twee
n cr
ysta
llite
s or d
efec
ts in
the
crys
talli
tes f
rom
agin
g th
e K
evla
r stra
nds
agin
g th
e K
evla
r stra
nds
––Pe
ak sh
iftin
g ha
s not
bee
n ob
serv
ed to
dat
e. A
naly
sis i
s Pe
ak sh
iftin
g ha
s not
bee
n ob
serv
ed to
dat
e. A
naly
sis i
s on
goin
gon
goin
g ……
……
––St
ress
mea
sure
men
ts m
ay p
rovi
de a
tool
in th
e sh
ort t
erm
Stre
ss m
easu
rem
ents
may
pro
vide
a to
ol in
the
shor
t ter
m
Que
stio
ns?
Than
k Y
ouTh
ank
You
Related Documents
