INTERIAMINAR SHEAR STRENGTH
OF GLASS-FIBER-REINFORCED
PLASTIC LAMINATES
Ne.1848
September 1955
INF ORMATION REVIEWED
AND REAFIIRMED
/960
This Veport is One of a Series
issued hi Cooperation with the
ANC-17 PANEL ON MASTICS FOR AIRCRAFT
of the Departments of the
AIR FORCE, NAVY, AND COMMERCE
1111111111F11111111(
11111111111111111111H
Wirimmuni.
UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST PRODUCTS LABORATORY
MADISON 5, WISCONSIN FOREST SERVICE
I n Cooperation with the University of Wisconsin
INTERLAMINAR SHEAR STRENGTH OF GLASS1
FIBER-REINFORCED PLASTIC LAMINATES —
By FRED WERREN, Engineer
and
B. G. HEEBINK, Engineer
Forest Products Laboratory, ? Forest Service
U. S. Department of Agriculture
Summary
This report presents the results of tests to determine the interlaminar
shear strength of glass-fiber-reinforced plastic laminates. Eleven different types of laminates were tested to investigate the effect of (1) type
of resin, (2) type of reinforcement, and (3) resin content on the interlaminar shear strength of laminates. About 165 shear tests were made after
normal and wet conditioning and with loads applied at angles of 0° and 45°.
There was considerable variation in the test results, but the epoxide
laminate made with Epon 1001 resin was consistently highest in interlaminar shear strength. Polyester laminates of 181 and 112 fabrics had
higher shear strength than did similar laminates with reinforcements of
143 glass fabric or glass mats. A decrease in resin content of polyester
laminates of 181 fabric appeared to result in lower shear strength at the
0° angle of load but higher shear strength at the 45° angle. In general,
specimens tested after wet conditioning had somewhat lower shear strength
than those tested after normal conditioning.
Introduction
In certain structural applications of glass-fiber-reinforced plastic
laminates, there has been some evidence of interlaminar shear failure of
the laminates. Interlaminar shear strength may be affected by various
factors, including kind or type of resin, type of reinforcement, and percentage of resin. The designer must have data available on these strength
-This progress report is one of a series prepared and distributed by the
Forest Products Laboratory under U. S. Navy, Bureau of Aeronautics
Order NAer 01610 and U. S. Air Force Order DO (33-616)53-20. Results
here reported are preliminary and may be revised as additional data
become available.
4Iaintained at Madison, Wis., in cooperation with the University of
Wisconsin.
Rept. No. 1848
Agriculture-Madison
values so that suitable laminates may be used in those structural applications where interlaminar shear strength is of importance.
At the time this study was initiated, few data were available on the interlaminar shear strength of laminates. It was the purpose of this program to determine the interlaminar shear strength of (1) laminates made
from a single fabric and four different types of resins, (2) laminates
made from a single resin and five different types of glass-fiber reinforcements, and (3) laminates made from one combination of glass fabric and
resin but having different resin contents. The study was undertaken at
the Forest Products Laboratory at the request of and in cooperation with
the ANC-17 Panel on Plastics for Aircraft.
The interlaminar shear, tensile, and compressive strengths of eleven different laminates are presented in this report. Some of the materials tested
were not developed or intended by the manufacturer for the conditions to
which they have been subjected. Any failure or poor performance of a
material is therefore not necessarily indicative of the utility of the
material under other conditions or for all possible applications.
Description of Material
All polyester laminates and the silicone laminate were fabricated at the
Forest Products Laboratory. The phenolic laminate was fabricated by the
resin manufacturer. The epoxide laminates had been forwarded to the
Laboratory earlier by the Wright Air Development Center, and the interlaminar shear properties, which have been previously reported along with
other datarl are included in this report.
Prior to fabrication of laminates at the Forest Products Laboratory, check
tests were made of materials to insure conformance with applicable specifications. The polyester resin was shown to meet the strength requirements
of Specification MIL-R-7575A, and the fabrics finished with Volan A were
capable of producing laminates meeting the strength requirements of
Specification MIL-P-8013A. The phenolic laminate, as fabricated by the
resin manufacturer, was requested to be "typical of a laminate of this
type, and of materials that conformed with applicable military specifications."
A brief summation of the fabrication methods used with each laminate is
given in table 1. Additional details of fabrication for the different
types of resin follow.
-Supplement to Mechanical Properties of Plastic Laminates. Forest
Products Laboratory Report No. 1820-3, 1955.
Rept. No. 1848
-2-
Polyester Laminates--Selectron 5003 Resin
The polyester laminates, each 1/4 inch thick and about 18 inches square,
were fabricated at the Forest Products Laboratory. The laminates were
fabricated with resin from the same batch, and essentially the same fabrication procedures were used. The resin was catalyzed with 0.8 percent of
benzoyl peroxide by weight. The lay-up of the glass-fiber reinforcement
and the resin was made between cellophane-covered, 1/4-inch-thick aluminum
cauls. Each panel was cured for 1 hour and 30 minutes in a press at a
temperature that was gradually increased from 220° to 250° F.
All panels were parallel-laminated except panel No. 117, made of 143
fabric, which was cross-laminated.
The three polyester laminates of 181 fabric were fabricated at different
pressures to obtain different resin contents, and were made from fabric
taken from the same roll. Sixty-nine sheets of fabric were cut and selected
at random for the three different panels. Panel 421 was cured at 14 pounds
per square inch, panel 421A at 5 pounds per square inch, and panel 423 at
50 pounds per square inch pressure. Thus, the panels were made from
randomized fabric and the same batch of resin under identical fabrication
conditions except for laminating pressure.
Silicone Laminate--Dow Corning DC 2104 Resin
The silicone laminate, nominally 1/4 by 18 inches square, was fabricated
at the Forest Products Laboratory. The panel was parallel-laminated of
23 plies of heat-cleaned 181 fabric which had been impregnated with resin
prior to receipt at the Laboratory.
The impregnated fabric was laid up between 1/16-inch cellophane-covered
aluminum cauls and placed in a press at a temperature of 340° F. and at
low pressure for 45 seconds. The press was then opened to "breathe" the
panel and closed to full pressure within 1 minute. The panel was cured
for 17 minutes at a pressure of 45 pounds per square inch and a temperature of 340° F., cooled under pressure, and removed from the press. The
panel was then post-cured in an oven for 16 hours at 90° C., 1 hour at
125° C., 1 hour at 150° C., 1 hour at 175° C., 1 hour at 215° C., 140
hours at 250° C., and cooled slowly in the oven.
Phenolic Laminate--Bakelite BVQ 11946 Resin
The phenolic laminate received from the manufacturer of the resin was
about 1/4 by 14 by 16 inches. According to the manufacturer, the panel
was made up of 28 plies of 181 glass fabric finished with Volan A and
parallel-laminated with BVQ 11946 resin. The manufacturer stated that,
Rept. No. 1848
-3-
after lay-up, the panel was cured in a press for 60 minutes at a temperature of 325° F. and a pressure of 100 pounds per square inch, to 0.250-inch
stops; the panel was then post-cured for 10 hours at 325° F.
Epoxide Laminates--Shell Epon 1001
and Epon 828 Resins
Two parallel-laminated panels were received at the Laboratory in November
1953 from the Wright Air Development Center, Wright-Patterson Air-Force
Base, Ohio. A description of the laminates, as furnished by the supplier,
follows:
"Panel No. 225 was a dry lay-up, nominally 3 feet square, consisting of
12 plies of 181-Volan A glass fabric impregnated with Epon 1001 containing 4 percent by weight dicyandiamide. The laminate was cured against
stainless steel cauls with two sheets of 0.060 inch alpha-cellulose as
padding between each caul and the adjacent press platen. Contact pressure
was.maintained for 20 minutes, followed by 25 pounds per square inch for
30 minutes. The temperature of the press was 345° F. The resin content
of this panel is 32 percent.
"Panel No. 226 was a wet lay-up, nominally 3 feet square, consisting of
12 plies of 181-Volan A glass fabric impregnated with Epon 828 containing 8 percent by weight of Curing Agent A. Cauls and padding were identical to those described above. The laminate was cured for 30 minutes at
25 pounds per square inch at 240° F. The resin content is 32 percent by
weight.
"The Epon 1001 and Epon 828 resins and curing agents are products of the
Shell Chemical Company."
Values irom Cured Laminates
After fabrication and cure were completed, each laminate was trimmed,
measured and weighed, and Barcol hardness readings were taken. Average
values of thickness, specific gravity, resin content, and Barcol hardness, 4 determined from Laboratory data, are presented in table 1.
Since eq 6h laminate was made by recommended and accepted fabrication
procedures, the panels are considered to be typical of their type. If
different fabrication methods had been employed, such as other laminating pressures, the resulting laminates would have had different physical
and mechanical properties.
Rept. No. 1848
-4 -
Testing
Polyester, Silicone, and Phenolic Laminates
Ten tension and ten compression specimens were cut parallel to the warp
direction of the top ply of each laminate, except that only five tensile
specimens were obtained from the phenolic laminate. Fourteen to sixteen
interlaminar shear specimens, at both 0° and 45° to the warp direction
of the top ply, were also cut from each laminate.
Tensile specimens conformed with the requirements of the Type II specimen
of Federal Specification L-P-406b.± They were loaded to failure in a
mechanical testing machine equipped with Templin tension grips. Load was
applied at a head speed of 0.20 inch per minute.
Compression specimens were 1 inch wide, about 1 inch long, and the thickness of the laminate. The length of specimen was such as to provide a
slenderness ratio between 11 and 15, as specified in Federal Specification
L-P-406b. Bearing ends were carefully surfaced with a surface grinder
prior to testing to insure flat and parallel loading ends. The specimens
were tested in a hydraulic testing machine at a head speed of 0.04 inch
per minute. Failure was a combination of transverse shear and crushing
of fibers.
Interlaminar shear specimens were of the general type used in testing the
shear strength of glue joints in blocks of wood. Sketches of the test
specimen and of the test method are shown in figure 1. The bearing edges
of the specimens were carefully machined prior to testing to insure flat
and parallel loading surfaces. The specimens were then mounted in the
glue-line shear apparatus (fig. 2). Load was applied with a mechanical
testing machine at a head speed of 0.01 inch per minute. In general,
the failure was in delamination between two adjacent layers of reinforcement.
Tension, compression, and shear tests were made after (1) at least 2
weeks' conditioning at a temperature of 73° F. and a relative humidity
of 50 percent, and (2) 2 hours' immersion in boiling distilled water.
Maximum loads were determined from each test.
4
–Plastics, Organic: General Specifications, Test Methods. Sept. 1951.
Rept. No. 1848
-5-
Epoxide Laminates
Descriptions of the methods used to test specimens from the epoxide
laminates are given elsewhere,1 and details need not be repeated here.
The interlaminar shear specimens were built up of three 1/8-inch plies
of laminate and, except for thickness, were the same as the specimens of
the other laminates. Wet conditioning for the tensile and compressive
specimens was 30 days' immersion in water at room temperature instead of
the 2-hour immersion in boiling water used with the other laminates. The
epoxide shear specimens, however, were subjected to 2 hours in boiling
water as were the shear specimens from the other laminates.
Presentation of Data
The polyester, silicone, and phenolic laminates described earlier were
fabricated specifically for these tests, and the results given are based on
tests of these materials. Results of tests of the epoxide laminates are
taken from an earlier report,I and are presented herein for comparative
purposes.
The results of tension and compression tests are given in table 2.
Average strength values for both the dry and wet condition are given, as
well as the average percentage increase in weight of the compression
specimens resulting from the 2-hour immersion in boiling water.
Table 3 presents the maximum, minimum, and average interlaminar shear
strength values, dry and wet, and at angles of 0° and 45° to the warp
direction, of five parallel laminates made of 181-Volan A glass fabric
and different resins. Table 4 is a similar presentation except that
data on five polyester laminates having different reinforcements are
given. Data showing the effect of fabrication pressure and subsequent
resin content on interlaminar shear strength of three polyester laminates
are given in table 5.
The average interlaminar shear strength of the different types of
laminates, as taken from tables 3, 4, and 5, are presented graphically
in figure 3.
Discussion of Results
The purpose of obtaining the tensile and compressive strength values
for the polyester, silicone, and phenolic laminates (table 2) was to
indicate the general quality of these laminates. In general, the
tensile properties were reduced only slightly after the wet conditioning
period, but there was an appreciable reduction in compressive strength.
Rept. No. 1848
-6-
The increase in weight due to boiling specimens was about two or three
times greater for the mat-reinforced polyester laminates than for the
fabric-reinforced polyester laminates, but the increase was still only
about two-thirds of 1 percent. The silicone laminate, however, increased
in weight about 7-1/2 percent during the period of immersion in boiling
water.
The 181, 112, and resin-bound mat polyester laminates all met the minimum
tensile and compressive strength requirements of Specification MIL-P-8013A.
Since the 143 laminate was cross-laminated, no check could be made for
conformance with the specification. The laminate made with the mechanically bonded mat failed to meet both tensile strength requirements, probably
because of the high resin content.
At the present time, there is no accepted standard method for making interlaminar shear tests. Various methods are used and others have been suggested, including tensile-, compression-, and flexural-type specimens.
Suggested methods which result in a reasonably uniform shear stress distribution over the shear area require a rather complex and expensive test
specimen and procedure.
Experience in determining the shear strength of wood and the shear strength
of a glue bond between blocks of wood led to the selection of the type of
specimen used in this study. This type of block-shear test obviously does
not apply pure shear stress to the specimens. It has the further disadvantage of requiring a rather bulky apparatus (fig. 2). When used with
wood specimens which are carefully prepared and tested, however, it has
demonstrated reproducibility and consistency of results. If shear specimens of laminates are also carefully prepared and tested, it is believed
that reasonable shear values may be expected. Although these values may
not be the true interlaminar shear strength of the material, tests of
different types of laminates, such as have been evaluated in this study,
may be expected to show the relative shear strength of the different
materials.
Of the 181 laminates made with different types of resins, the silicone
laminate had much lower interlaminar shear strength than did the other
laminates. The epoxide laminate made with Epon 1001 resin had a somewhat higher shear strength than did laminates made with other resins.
The interlaminar shear tests of the polyester laminates with different
types of glass-fiber reinforcement indicated that the 181 and 112
laminates had the highest and about the same shear strength, while the
143 and mat-reinforced laminates were slightly lower in strength.
Within the range of resin contents tested for the 181-polyester laminates,
dry shear strength at 0° appeared to remain about the same. At the
lowest resin content, however, the wet shear strength drcpped appreciably.
Rept. No. 1848
-7-
It seems reasonable to assume that further reductions in resin content
might further reduce the shear properties at 0° loading. Shear strength
at 45°, however, generally increased with decreased resin content.
The shear strength of the 181 laminates was, in general, higher at the
45° direction of loading than at 0° loading. This may possibly be due
to the "nesting" of the threads in adjacent laminations, which offered
lateral resistance to 'shear movement. In the polyester laminates, this
difference became more pronounced as laminating pressure was increased
and resin content decreased, which, within limits, is to be expected. The
181-phenolic laminate also showed an appreciable increase in shear strength
at 45° over that at 0°, but in the epoxide (Epon 1001) and silicone laminates the difference in shear strength at the two angles of loading was
smaller. An appreciable directional increase at 45° was found also with
the 143 laminate, but the increase at 45° was less for the 112 laminate.
Since the 112 fabric is much thinner than the 181 and 143 fabrics, "nesting" effects would be expected to be less pronounced.
There were no definite directional effects in the mat laminates. If
fiber distribution and orientation is uniform within a mat, properties
would be expected to be the same in all directions in the plane of the
laminate.
Wet conditioning, in general, appeared to result in a slight reduction
in shear strength of the laminates, but results were somewhat erratic.
Wet strengths, on the average, were about 7 percent lower than the dry
strengths for the polyester laminates, the greatest reduction occurring
in the mechanically bonded mat (tables 4 and 5). Wet conditioning had
the least effect on the epoxide laminates, with only a minor drop in
strength for the Epon 1001 laminate and increased wet strength for the
Epon 828 laminate.
Summary of Results
Interlaminar shear tests were made of 11 different glass-fiber-reinforced
plastic laminates. The tests were made to determine the effect of (1)
type of resin, (2) type of reinforcement, and (3) resin content on the
shear strength of the laminates. Data were obtained also to show the
variation of shear strength with direction of loading and conditioning
of specimens. Briefly, the results may be summarized as follows:
Rept. No. 1848
-8-
(1) The highest shear strength was obtained with the epoxide laminate
made with Epon 1001 resin, and the lowest shear strength was
obtained with the silicone laminate.
(2) Of the different types of reinforcement, the 181 and 112 laminates
had generally higher shear strength than did the 143 and mat
laminates.
(3)
Dry shear strength at 0° remained about the same within the range
of resin contents of the 181 polyester laminates. Wet shear
strength at 0° dropped appreciably at the lower resin content.
At 45°, however, shear strength generally increased with a decrease
in resin content.
(4) In most cases, the interlaminar shear strength at 45° was higher
than at 0°.
(5)
Wet conditioning generally resulted in a slight reduction in interlaminar shear strength, the greatest change occurring in the polyester laminate and the least in the epoxide laminates.
Rept. No. 1848
-9-
1. -18
H
I
o rd
rn
H
o
Pi
'ci
0 rcl
P21• •
a)
0
0
F..
rz 0
0
fa
• •
cH
03
a)
0
H
• •
a)
tto
•
c)
1-1
cH -P
•H •H
o
a)
gi
• •
•
•
0
11I
••
••
•
• • • •
• •
••
in
••
N
•• •• .. .• ••
CO
H
t---
••
H.
O.
\0
••
• •
H
H
••
PI I
H
• • •
•
• •
rn
Lrn
0.3
cC)
in
W
•
..•
H
H
••
••
01
crl
••
••
•• ••
• •
• •
• •
• •
•
•
H
111 0 0
H
••
••
1.1.1
t
•
•• •• •• •• • n• ••
I
0
0F-4
a)
0 133 CH •H
.0 0 r-i
•• •• •• ••4 •• •• ••
••
••
1.11 \ID Cr
)
co
•
•
• •
•
•
•
•
• •
• •
•
•
P•i
•
W rrl -- H H
Cll
01• NNN N
• al
• H
• •
• •N
• H• r--1
a.)
2'
0
rn
C---
H
••
r'
OD 0 0
N
.-4- C.– CO CO CO
H t--1 H H H
LrN
–I-
N- ...- cv o t----
0 a)
•H 0
0 1:1
•
••
CV
N
crn co
• • N-• Cl1•
ai t--- \0 01 CO
Cr) 01 N (v1 RI
c.3
H
I
• •
re.)
W ON .--1• Lr\ op
co t--- on N- CO
•
•
•
• •
m co
Cd
N
a)
• • •
0
0 A-'
a) 0
0
'0
• . • •
43
0 $1
..-1 ii)
0
CO
••
•• ••
NN
COM
CYINCO
C\1 01
••
••
••
••
••
•
•
•
H
•• •• •• •• •• ••
• •
• •
•• ••
co CO
N N
N N
I-1 H
••
.•
N-
CC)
•• ••
•• ••
••
M M
0
0
0
0
8
0
0
0
0 0
trn Lr'N 1..r\ Lr3% 1r\
LIN
II\
MM MMM
0 0 0
PI 0 id 0
0 0 0 0 0
O
0
ta
F+
9-1
0
4
F-I
F-I
I-3
F-I
0
F-F
-P 4-.1
-P -P-P
0 0 C) 0 U
0
a)
a)
a)
a)
a)
1.1
H
P-1
H
H
,--1
H
0 0 a) g) .a)
a)
CCI ca co tr) Crl
ci3
•• •• •• •• •• ••
••
••
••
..
.•
0
V..) •-1
F-II --
TIN
0
F-I
•• ••
+a -2
0
v
8R
H H CC.'
,-.-1
0 00
H
ce C)
cn 8
PI
12)
••
•• ••
Ai
.
• • •
F-i 5-io) S-1 k k
k
k
a)
a)
a)
a)
a)
a)
c)
4-0,
+3
-P
+3
-IA
4-,
4-3
+3
0H
a) a)
CI U) ca ra r.a
r3)
0
0
rd rd
VI
0
0 0 0 a)
C)
0 C.) 0 • -1 -r1
a) -1-1
Z X ,4
1Z •,-1
1-1 H H H I-1
1-1
H I-1 0 0
0 0
0 0
0 •H ,4 P4 Pi
0
P-i P- ad I:14 P-t
P-1 Er) Ill CA
P-1
0 0
•• •• •• •• .. ••
• •
. .
••
.• •.
••
.•
C_)
0
Ao
0 C.) 0
01
a)
c)
O
('
IA
a)
iz
rry
>
t)
0
ca 14 q
eq a) N al
H H H 01 en 0Z OM
a)
• ••
••
••
••
••
.•
al
•• ••
al
•• ••
7
0C, CO CO 00
H .–I
••
••
4-1
..
..
• C7
Ctj
rd +3
V.
rd •
0
JD 00
• rd
cd 9
O
O10 –1- 1.11\ 0
0J ai N N
W\
LIN C1 al
•
°
,4
CO
0
.n
I
Cad 0
•
gCO
N N 1-1
U)
9-1
9-1
cd
Cry 0 0 u
• 0
CO C) CD H .$
.–I H H H H
•• •• •• •• •• •• •• r
.4
> >
F-1
c l CH
A-D
;-1
XI
cd
0
H -H •r-1 9-1 •r-i
0
-r1 •H
•H
N P F-i I-c F-4 I-11 .0 C \ .3 I
rd F-4 F-4 F-1
(t) •sD .0 _n
-d -1-341-,
-P0 rd0 .130 .0
03 ci
0
0
Cci al
0 ni
rti •T••1 r•TA 174 =c
1
9:11
rzi PT-4 rfi
0
<4 <4 <4
<4 <4 <4 <4
<4 g 0cri g g II)
0
i 0 0 0
0 0 0 0 0
+.1
ei 0 cd 0 ra 0 0
1 4-3 0
0 cd
H
1-1 H H r-1 0 d
cd e-1 J-1 H
0 0 0 0 0
•n-i a) 0 0 0
00)
cH
8
•-1
rd
d
,0
9-1
ci
9-1
r=t
A)
c4
a)
H •
H 7.1
<4 (a
0
:E1
• 0
co
a)
co •1-1
a.) Icq
H
qtr
P., al
0 0
H r1
• •
4-)
••
0
c.1 0
4-1
r-)
eb
cci Ea
Ea
•• •• •• •• ••
Ti
0.1
a)
•
••
to
•
C1-1
• • •
•
•
02
•
r:14
• • •
9-1
-1-1
0
g
to
•
.0
• ••
-P
•
•
A a)
co
0 Pi
0 0
• • .•
E-1
-I-)
co
• •
• •
•
••
4-)
el 1-)
a) Ed
P-t
qi
9-I
CO
1:4
g
H
•
$.1
a:1
••
a)
q-1
• •
•
•
• •
• •
t—
•
• •
••
,3
8
0
• •
••
• •
• •
••
8
0\
2
01
LC
(-0
en
CU
CU
• •
8
ErN
CU
t—
•
.0
•
• •
• •
8
H
• •
0
LI1
0
• •
••
0
LC\
o21
0
0\
ON
a
a
UN
••
__I-
••
LrN
••
FA
P. -
8
O\
8
1.11
Er\
0
If\
CO
Er\
..
•
•• •
c-n
0
0
LE\
0
0
Ji
()
a)
H
8
8
On
V)
0
OD
ON
8
••
••
••
••
••
••
:9
C-s
Lr
H
s
..
0
0
0
E.)
E.)
a)
H
a)
Ea
k
C)
a)
H
a)
Ea
..
-1-3
a)
I-1
a.)
4-)
to
a)
H
0
a.:
H
0
P4
••
••
to
H
o
111
H
0
C1-1
H
0
• •
..
..
;-1
a)
co
•
•
•
.
••
CO
CO
a
ON
..
8En, 0111 8111
-P
$.4
a)
••
a
11\
0
0
k
N
0
..
0
0
li-N
0
0
01N
ON
O\
En
..
a)
8
..
..
to
8
rn
En
$.-s
9)
••
Lc\
••
O\
ri
••
..
..
4-)
••n
irn
rI
••
en
H
C)
$-I
0)
C91
••
a)
H
a)
E0
f
0\
cn
a)
H
a)
cf)
••
•
0
..
P
••
H
01
0
0
if \
0
0
U-N
CO
••n
C r)
•
•
•
•
•
•
•
•
•
••
8
cy, 8
cr.)
••
• •
LIN
)
to
a.)
0 a)
Z-01
a) -P
• •
0 g
0
rd
0 a)
crl H
o oi
H
• •
0
0
En
0
0
rd
to a)
• •
oo's
cn
cn
X
0 a)
a)
• •
•
•
L1
ri
M
••
1:14
0
co
•• ••
.0
(7, u-,
(.1
CU H CU
•
•
•
•
•
•
•
•
•
••
S-1
0
k
0
0
\-0
—1-
0
a
H
as
cr)
..
0
a}
H
;-1
a)
-P
to
a)
H
0
..
..
ID
H
a)
En
••
$.4
a)
4-)
io)
0
P-1
0
P.'
.....1a.
H
H
a?
A
..
..
c)
Cl]
-.-1
H
2a)
-1:-i
••
43
03
rcl
9)
rd
0
o
4-)
a)
0
cid
0
H
.o
cd
ctl
;_g
14
i--{
CS
. 1-1
F-4
.0
71/
c.)
0 0.
• •
rt.!
0
0
.r1
k
.0
a3
Ct.
H
C) Ea
CO
V C)
X 14H H
• •
• •
-0-
7:11
g
.0
9-t
I
0
0
ozi
.0 H
H H
CO CO
H H
•• • • • • • • • • • • • •
-1-1
azi
Z
▪ N rte{
01
co
0.1
_1-
• •
_I-
.•
01
LC\ VD
CU
CU
Ckl
•
0
o
CID
4-I
PI
02
If \
CC1
-1-3
03
cg
--.1-
.6\cis
tror.
12ISHZ
C;'‘.6'
•• ••
•• ••
•• ••
00
C-00
NH
a a
Lr\Lr\
• • • •
80
1—I&
H
• • • •
00
Wt.-0 C.—
\Sir':
(.
91
uNm
00
*I-1..COVN
m '0 0\
.0. .,
N \O w\
8R
Fo.c.4.
•• ••
•• ••
•• ••
•• ••
•• ••
t.'"t"
tsts'
r- r-
COM
t` r"
• • • • • • • • ••
(L)
t20
•
03
$4
•
•
....
a
OH
nOVS
• •
••
00
0
•
N 0 \
CO N-
•\0••
••
1-7,21 '
••
••
H 0
0\0
eas a
Lr0."
•• ••
••
••
00
HO
•• ••
•• •9
.1-1
•
0. 0
Ckl VD
g S).
0 0
ii-N_I-
W
•
N
Mtr\
OW\
4::r ••
-1-0
•• ••
• • • •
•• ••
00
oo
00
m•-1....1.m
4.,:i.
O
Ln8
a...4s
• ••
•• ••
,..4
oc,
2
•• •• •• •• •• •• ••
•Hr:1
•• • • •• •• • •
00
CO 0
t"-- 0\
NO
C.:4-1'
....
P..
• ••
•
o
m•
4
M
•• •• •• •• •• •• ••
W
• • • •
•••
v-I
• •
DO
F-1
-P
0 0
00 0 \
mai
•• ••
0@
.1 ts.na
\oil\
•• •• •• •• •• •• ••
0 TIM
X)C1d.100
9000
410
t
0 Cr \ cc)
cor4
•• ••
08
lm..
a
Lr\ LA
•• ••
eel
0 13)
0 0
H
c—co
•• •• ••
•• • ••
CH
[Cs
.. a
\JD Ir \
N
•
.4-1•
03
•
N
0
0 0
•
0
0
8
m
N \ 0
trN...1-
OM
.....%
....1-ON
m0
aft
•N a
HH
• • • •
•• ••
O
C\ O\
00
8cTi
....1.1r.
mN
mOn...
Li...N.
•• ••
••
MW
a0 a0
•• ••
•• ••
•• ••
•• ••
ONC-WOIN
• • • 41
2+0) A3 A3 A3)
A3 A3
• •
• •
• •
••
• •
• •
••
•• ••
•• ••
Cr)
00
LC\
8
a)
H
0
O
a) •
co
8
W
a
•• ••
•• •• •• • • •• • • ••
•• •• •• • n• •• •• ••
H
0
0
-o
m
o
a)
rd
H
0
N
•• ••
o
PA
g
•• ••
Cc1
0
<2?
8
•• ••
.•
• • a•
O
0
••
4,0
0
-r-I
7201
•• ••
• ••
OD
H
z0
4.;
a
Lr,
LC \
(7)
P-1
•• ••
.
•+-1
co
.
P-f
• ••
0
a)
Fi
0
p4
0
(1)
H.
m
.
RA
10
a)
•• •• ••
4
A
•
0
.14
-P
cri
a)
•rt
U)
0
0
iA
0
5
0
0
0,
a)
cF4 ri
H
H ra
4_,
Cd
a)
0Q
9g
Li‘, a
1.11 0
a
Cfl
a
•• ••
•• ••
•• ••
•• ••
•• ••
c
HM
MM
∎Os.
wh
aa
-d- rn
•• ••
a n
l-nrn
•• • •
00
a. a
R0
N-c?,
Lr11-1
aa
r, 8
c
COC-aa
88
•• ••
•• ••
•• ••
•• ••
aa
W\
a a
8
R
\-001
a a
\i)L1-\
•
• •
0
o a) a)
1010
•• •• ••
O
3 fai
-P
c3
••
••
°
t
5:1
a)
1.-1
• ••
.
•-1
.
co
.
P4
• ••
•
Hal
•
m
•
• ••
•
..-1•
k
cd
co•
a)
.1:1
co
P.,
•• •• •• •• •• • ••
F -{
a)
gclAo0
O m a)
P4 0
•• ••
•• •• •• •• ••
1
48
•• ••
o o
c0 Q
a or%
a
•• ••
88
Cn ITN
aa
n t n. 4••
id
rl
Fa
a)
0
0
0
crt
(IA
rI
rd
NOV
o
•• •• •• •• •• • ••
00
0 cr)
asa
trN
•• ••
cd
Fa
i
a. a
• ••
•• ••
a0a
UNIX\
•• ••
a
CO
0
M k.°
-4-
aa
•• ••
•• ••
•• ••
o
en
o
o
t--
ww
c0
aa
•• ••
00
\OM
0 t•-•
aa
•• ••
00
MU
Cn
aa
sg
•• ••
00
it1 11.1
aa
•• ••
00
••
••
•• ••
•• ••
•• ••
›...0
..1.,
fr
AN AN
•• ••
•• ••
•• ••
•• ••
0
d
H
0
0
d
H
0
>
••
••
•• ••
0
01
Ha a
c0 LIN
0
00
NN-
•• ••
•• ••
co co co
•• ••
›)4,
k a)
•• ••
.a .I.,
A
•• ••
F-1 a)
A
•• ••
•• ••
0
0
P
g
•• ••
H
rct
0
0
p4
rd
0
0
.0
0
0
•
O
0
Qt
S ri
H
E4
0
HN
co co t-- co op co
k,0
4.1 CO
d
.H
4
HO
H
N''-1
0
CH
•• •• •• •• ••
••w
••
m
-P
rd
A-)
0
g o
C--CO WC-- COW
Pi
co
aw
1111IN
.• ••
4:4-1
o
0
0.Q
l c' t)
•
o
0
80
tr\
k
p4
4-)
FA@
N n0
0
-r1
a)
F-c
m
r.4
M
.4*
c0
•• •• •• •• ••
°'0
H
0
H
-rid
• ••
•• ••
•• ••
H
•• ••
ti
0
w
r0
0
_0
•• ••
co
-N
rd
9
..00I
H
U)
a)
gg
0
•• ••
Pt
a
a)
o
L.rN
•-4
$-1
CD
Ci;
ctl
a)
F•4
a)
crt ra
c1-1
•ri
•• • •
•
••
0
CO
•• •• ••
9
4-)
P,4
F-1
as
••
1:14
1.11-*
••
••
••
a)
bD
••
••
cd
••
H
1-ICO
.5
‘q
.5
••
0
co
con
Lf\
••
@@
••
2 2
..
UN
LIN
••
••
00
(r3,8
*5
\O V\
.5 .5
VD If\
••
••
t-- ON
••
••
••
••
CO
L--
•• ••
0 8
co
t— ON
••
••
0 .Q
\L)
N-
+)
rid
a)
0
o5
••
bD
a)
al r-i
a)
co
••
0 0
0 0
n-1
al
28
NO ON
.5 .5
\D U
N- t--
4-I 0
q
a)
••
N\.0
a)
a)
••
••
0!
•• •• •• •• ••
co
s
••
•—I
ON ON
CO
a)
a)
N LiN
Lf\
ta0
rtj
c91@
8
1:14
+)
••
••
0
•• ••
• •
0 0
cn
0
••
0
0 0
H ON
(Y)
-1- -I-
•• •• ••
1-1
05
9-1
ca.
cn
tri
ro
H
131
••
•• •• ••
a)
CO CO
CO CO
•• ••
•• ••
+)
-P
•• •• •• •• ••
••
•• ••
"
-1
3C)
••
9-;
b0
0
.C.)
r4
0)
•• •• •• •• •• ••
-I-)
4
a)
+)
0 0
irll
•r-1
tO -P
c0 CO
13)
A
•• ••
s\
a) 0
o
a)
C)
•• •• •• •• • • ••
••
41,1
•• ••
•• ••
a)
0 0
•
Ill
co
•• •11
PI
-,
•• ••
•
CO
in
•• ••
••
tr.
•• ••
c0
--1c0
0
•• ••
4)
a)