LOAN COPY
Please return to:
Wood Engineering Research
Forest Products Laboratory
Madison, Wisconsin 53705
Supplement to
13IJCICLING or FLAT PLYWOOD PLATES IN COMPRESSION,
SHEAR, OR COMEINEID COMPRESSION AND SHEAR
13ucklinc Tests of Flat Plywood Hates in Compression With
Face Grain at 15 0, 300, 45 0, 600, and 75 0, to Load
Information Reviewed and Reaffirmed
Aucust 1955
INFORMAIION REViEWED
AND REAFFI.RMED
1950
This Report is One of a Series
Issued in Cooperation with the
ARMY-NAVY-CIVIL COMMITTEE
on
AIRCRAFT DESIGN CRITERIA
Under the Supervision of the
AERONAUTICAL 130ARD
No. 1316-G
UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison 5,Wisconsin
In Cooperation with the University of Wisconsin
BUCKLING TESTS OF FLAT PLYWOOD PLATES IN COMPRESSION WITH
FACE GRAIN AT 15°, 50°, 45°, 60°, AND 75° TO LOAD2--'2.
By
C. B. NORRIS, Engineer
and
A. W. VOSS, Engineer
Forest Products Laboratory,2 Forest Service
U. S. Department of Agriculture
This report presents test data in substantiation of formula (16),
2
P
k
er c EL ah , for the buckling stress of pl ywooddplates in compression as presented in Forest Products Laboratory Report No. 1316, "Buckling of Flat Plywood Plates in Compression, Shear, or Combined Compression and Shear." These data were obtained in the same manner as the
data presented in Report No. 1316-D, "Buckling of Flat Plywood Plates
in Compression with Face Grain at 0° and 90° to Load."
For a discussion of the problem, the materials used, the system of
matching and marking specimens, and the method of test, see Report No.
1316-D.
Very few modifications of the procedure used in the compression tests
of plywood at 0° and 90° to the direction of the face grain were necessary when the direction of the face grain was placed at other angles to
-This report is one of a series of progress reports prepared by the
Forest Products Laboratory relating to the use of wood in. aircraft.
Results here reported are preliminary and may be revised as additional data become available.
?Original report dated November 1943.
Maintained at Madison, Wis., in cooperation with the University of
Wisconsin.
Report No. 1316-G
-1-
Agriculture-Madison
the load. Modifications were necessary, however, in the layout of specimens and plate sizes, and in the determination of the critical buckling
load of thick specimens.
A modification of specimen layout was necessary to obtain specimens and
matched coupons for pack compression tests having the face grain at the
same angles to their edges. The layouts were as shown in figure 91.14The plate sizes were again computed from the elastic properties of the
plywood to obtain the length-width ratio for the formation of a buckle
in a single half wave. Dimensions of the plates from each panel were as
shown in table 15.
The second modification of the procedure used in the compression buckling tests at 0° and 90°, for this series of tests at other angles, was
an improvement in the technique of observing the critical buckling load
of thick specimens when the critical buckling load was greater than 0.75
of the proportional-limit load. It was observed in the effective width
tests (Report No. 1316-E) that the rate of increase of the average
strain at the center of the plate decreases and that the rate of increase of the average strain at the transverse centerline near the edges
increases at and above the critical buckling load. Therefore, in addition to the buckling deflection, strains were measured at three points
on both faces of the thick plates, at the center and at 3/8 inch from
the edges on the transverse centerline. When the lateral, or buckling,
deflection curve gave no indication of a critical buckling load, the
critical buckling load was taken from the strain curves as the load at
which the distribution of strain at the center and the average strain at
the edges started to change rapidly. A typical example of the method is
presented in figure 92, in which the buckling deflection curve and the
strain curves are plotted.2 It may be noted that there is a sudden
break in the "center" load-strain curve at a load of 2,800 pounds which
is taken as the critical buckling load in this instance.
Except for these two modifications, the same system of marking and matching of material, and the same buckling-test apparatus and procedure were
used in this series of buckling tests in compression at 15°, 30°, 45°
600 , and 75° to the face grain direction as were used in the compression
buckling tests at 0° and 90° to the face grain direction.
–The figures and tables in this supplement are numbered consecutively
with those of Report No. 1316 and its supplements, 1316-B, -C, -D,
and -F.
-The Southwell method of determining the critical load is not applicable
to flat plates in compression. (Report No. 1316, page 15, and Report
No. 1316-D, page
Report No. 1316-G
4.)
-2-
Presentation of Data
Data obtained in this series of tests are presented in table 15, :together with various computed values and in figures 93 through 102, and 104
through 107. All test data from each panel are tabulated following the
panel number given in column 1 of table 15. The test data for the
plates are given in columns 2, 3, 4, 6, 11, 12, 13, and 15. When only
one plate was obtained from a panel 24 by 24 inches, as for compression
at 45° to the face grain, columns 11 through 19 and column 20 are omitted. Data obtained from the tests of coupons are presented in columns
20 through 23.
In figures 93 through 97, and 104 through 107, are plotted the ratios
of the observed critical buckling load to the proportional-limit load
against the ratios of the computed buckling loads to the proportionallimit load. Two critical buckling loads were computed for each specimen by the method presented in Report No. 1316, first, (figs. 93-97) using
assumed equal to
k,
as given in figure 12 of Report No. 1316,
k Soo
kc.
c
and second, (figs. 104-107–using the values of ES-- obtained from these
CM
tests as discussed later. Figures 93 and 104 show the results of tests
in which the load was applied at 15° to the face grain direction; figures 94 and 105 at 30°; figure 95 at 45°; figures 96 and 106 at 600;
and figures 97 and 107 at 75°. These figures present graphically an indication of the accuracy of the method used for computing the critical
buckling load. Only the data included in the range for which the critical buckling load is from 0.1 to 0.9 of the proportional-limit load are
significant in determining the accuracy of the formula (Report No.
1316-D, pages 5 and 6).
For tests within this range, the average ratios of the observed critical buckling load to the critical load computed using kc assumed equal
coo
k to
are:
so
Angle of compressive stress
to direction of face grain
Observed critical buckling load expressed in percent of computed load
15°
30°
45°
6o°
75°
68
82
99
92
Report No. 1316-G
88
-3-
The curves in figures 93 through 97 and these percentages show that the
k
k
assumption that c equals -2-- is correct only for the plates in which
k Sao
k Ca,
the face grain 176,1 an angIF-Of 45° to the direction of the load, and
gives high values of the buckling load for other angles.
The method of computing the critical buckling load is given in Report
No. 1316 with the formula for the critical buckling stress
2
h
p = k E —
c L a2
cr
In this formula, h is the thickness and a is the width of the plate.
These quantities were measured and checked at the time of test and are
not questioned. The value of the modulus of elasticity of the individual plies in a direction parallel to the grain (E L ) was determined by
static bending tests of coupons and the formula
E = 20 (E + E 2 ) )
2
L 21 1
in which E and E are the bending moduli of elasticity of the plywood
2
1
parallel and perpendicular to the face grain, respectively. This formula assumes that the ratio of the transverse to the longitudinal modulus
of elasticity of the individual plies is 0.05 and has given satisfactory
results previously. The value of E L is, therefore, believed reliable.
c
The only other term in the formula is k.
This term is made up of two
factors, ic e . which is mathematically determined by the energy method and
applies to panels infinitely long, and a correction factor for length.
It is assumed that the correction factor for length is in error. The
k for
value of k was determined for each specimen from the value of cco
c
each specimen by the use of figure 12 of Report No. 1316. In that figure the ratios of these factors for panels subjected to shear stress applied parallel and perpendicular to the direction of the face grain
kS
(_=_..) are plotted as ordinates and the ratio of the length of the panel
soo
to the length of a single ideal half wave k--J as abscissas. The ordinates were assumed to be the same for '
k Ow
Report No. 1316-0
-4-
•
This assumption was studied by computing an observed k c from the observed critical buckling load, the E , and the plate dimensions. These
L
observed values of k c were divided by the values of k Cm obtained from
Report No. 1316. These ratios were plotted as ordinates and the ratios
of — were plotted as abscissas in figures 98 through 102. Also shown
b'
k
in these figures by dashed lines is the curve for k from figure 12.
sm
It is apparent from a study of these figures (98 through 102) that the
k observed
k
s
ratio of c
does not agree with --- when the load is applied
k
k c m
Soo
at angles of 15°, 30°, 6o°, or 75° to the face grain direction.
It was assumed that the values of k
Cm are correct; and that the ratios
k
s
-- are not equal to — . Therefore a new group of curves similar to
cm
sm
figure 12 of Report No. 1316 were drawn for each angle between load and
face grain. In drawing these curves, it was assumed that the form of
the curve given in figure 12 of Report No. 1316 is correct. The new
curves were, therefore, obtained from the old one by adjusting its ordinates so that the new curves passed through the average values of the
ks
test results and so that the value of the asymptote ( 17 – = 1) was not
s00
changed.
This adjustment was made by determining a factor F from each test using
the formula
F=
k observed
( c
) k co
m
I
1
and then finding the average factor for the tests at each grain angle.
Using these average factors, the new curves were drawn for each angle
c
with kk— = 1 + F
s - 1 for all values of .
Cm
S oo
Report No. 1316-G
-5-
Curves corrected in this way to agree with the observed data are preIce
1 .-- at various angles to
sented in figure 103 as a family of curves for 7
CW
the face grain direction. The average correction factors, F, used are:
Correction factor
Angle of load to
face grain direction
0.47
.58
15°
3o°
45°
6o°
75°
1.00
.86
.66
The critical buckling loads were computed using this method for the dek
c
termination of --- and are plotted in figures 104 through 107.
k
coo
Conclusions
The critical buckling stress of flat plywood plates in compression with
the face grain at 15°, 30°, 45°, 6o°, and 75° may be computed by formula
(16) of Report No. 1316,
2
h
p = k E
cr
c L —
a2
if the curves of figure 103 of this report are used for determining kc
instead of the curve of figure 12. The values obtained by this method
agree with the average experimental results obtained.
The curves of figure 103 have not been experimentally determined
throughout their entire lengths, but each curve agrees with the average
experimental results. The curves were drawn according to the form of
the curve given in figure 12 oi Report No. 1316, and represent the best
available information.
Report No. 1316-o
-6-
From consideration of the data in figures 98 to 102, it is evident that
k
c
values of — given in figure 103 are in best accord with the experimenk c.
tal data for 0 = 45°. The deviation of the data from the curves of
figure 103 is greater for 0 = 30° and e 60°, and still greater for
= 15° or 75°. For the grain inclinations of 15° or 75°, the ratio
k
ranges approximately 20 percent on either side of the mean. Therecm
fore, the lack of data for a wide range in values of 12-- and the deviab'
tion in the observed data at the tested values of -- should be given
b
due consideration in using the curves of figure 103.
Report No. 1316-G
-7-
.3-18
§1
........
”9
2 2 R gi 2
.=.1Lii.
,P2 "
j
4 3 :.: rr
:22
gi.1.
" " R n R
2 7. 2 2 S
R
;;;;;;;;;;.];;;2;;;;;;;
3 3 3 5 3 5 : 5 5 5 a 7 a 1 5 5 :i. . 5 5 5 5 5 5 5 5 5 5 5 5
.2 .3 3, .12
2 3, .Sa, .4
8. 2.
43 2.42 2.4 45.3 3
,4 42 3; 3. !,: .7
1.
1
!!,wF., .4. zrzs
4 4 4 4
.
g ssf...s. i. s.
-7
2222
4444
2222
22,3E
2222225222:712 : °
..............
.r.
4.; 2222 3 4'
111111
4
2322
4444
=
tl
R F; 7:3
5
F.77
44444
22,323:22232.11'222g222
4 R:
221. m$ 4 4 4 4 4 4 4 F.: z" :5 Et"
4 E. 1 1.
2°22,2332222s...:2222;22.23..rsxsz..ss.?'..
.4 4
: : ;
; 4 : :
:
222?
44
2222
8 EEE I 'l
44
:•222
223
82 ?1 7._ 4
i=i
4 4 4 4 aa..;:a
4 4 4
g
a;
44
4 4 ..
..
4
4
r.
8
1222
§M 22
4
4 4
; 4 4
44
a;
..........
a 4
4 4 :E:. -: 9 222222;222222228:1228S2F.A8-2.2.2s..2,2;
9
9 9
9 9
•
I
1
4 si20!:,..,;!!:12`1 :78 F. R
41
4
2
R 2 n$ z:$: n$ 2 2 2 2: 2 2 2 5! 2 2 2 S$ 2 2 2 2 2 2 2
222222222222
2
2
a ca
2
4 a
"
24
2
4 4 4 4 4 4 4 4 4 4
tl
44 4
3
222222223i
1*
s
2222,
?44..
5232
4 .4 4
St2
222
t; SR
=2222
21
a s
3, 2 ta 2 N 3
4444
444444'4444
ri
144444
gg "
22 R 22,22 ei
E
2223E2
4
4 4 4 4 4
222222232222
4 4
H.
4
4 4 4 -7 4 4 4 4
EE22222,222
444
44.
°222222322.2222222,225
2 4 4 4
tl 4
.4 4
0 .0
a
4 4 4
4
4 4 4
S"................
. 2 X 32222.23222121 9"
.3
2222222222$222222222522
2222
822222222222...0.222222
XZZAISZ2ZS:LIZZ'gg8,74,TAX09 22
222222
.3.
3
3
;i•ii;E:131:i3333di
a4-4'°33333
333 0-32333:133
5i:
13
kb
. 99 9 9°9119 9 ,,:-..a.
.4 .;333.13TiliE3" :-'3°I.: EFi as 292°4'31:43E31
1 n 9 " 9 " 9 9 . 9 9 9 n .. 9 9 n ° .. 9 ° 9 919 . 919
1
51.
i
4
5`;:i3'5 •-xx4
i313
3E:
31
3
2.1
113 3i
I
41
5. 55.
4
4 4 1. 4 2_ 55_ 1. 1 4 4
4.
4
3333;333x1r.st1313333333313;3313333133.1113333333
4.-7..7.4
.
s22
iE
33
tilt
4
EE
3.4
'
1
Et
1. 4
33
E.
11
Et
444
k
44
444
44
II
31
33
13
I 1.44
13
A
5555
41
4
3
92
.94
5
Ell
EEi
„33
4 55
4:1.4
1:
144.141414.44441444
E1
4 3 441141444
I
0 4! 3. 3. a 3.
i5i;EE6
...
4 4 .
.7 ;
4.
4.
9: !
1.
n1 A
3E3
44
13.
IS
;FE
11
33
3.3
II
4 4
1
gg
7.3
12
s
212
a
4e
-
tra
2`.
3
g
4.4
3333E3sig
23111 : 3 2'.2 22 3.2 2
s!
22;
..
22232222 222
2 2 3 2
•
Cif
lis
1E;
3.
4
4
°
4 4
4 4 1 5;r1i
44444
4 4 1 3.1 1
EWE
44444
34133333Z.E F
5.333.!
1.-i12:4221a;
3.33
.::.;
33i33332333's3i5E:33?....ess,
4' .1'
'
A .7 .7
4 4
.4
•7
:
A
21444
33 23§3.33 4. 4
4
El!
32333E1
A
22g.ki
13 i,S€E33- 23
3E3
2333.1Exakg:Es....v.ss
A
!=-;.11
1
1
312.
E?111136'03333331?..ilii:333„1
A
lts:a
13322223223
III
44 4
3 2 322333. 3333 32W13111331
7.1:1!.11
11219222,212
213
.7 4
1:131Iltg.33001g0tgag.r:5:3313
3. 3. 4 4 4
°
j
="
•
4;
g
"44
4 4 4 4 4
5 5: 4
4.iI44444144:":1114411.
4: 4 1 4 4 4 4 4 4 5 5-E.4: 4. 4. 4. 4. 4.
..:ft4. ,11:si g sl.tia p o$:ttrasal::.11
a
'4 4 4
ga..11:;:11
s
s
Sit 21f 6"
04.
co
co
0
o•.
Table 15.--Test data and computed valusi_fop booklins test plates and coupons (Continued),
Properties of plate material
Average modular of wisetioity
in bonding
Compression buckling test plates
Loaded at 450 to direction of face grain
Psnel
no.
*expression
Length
7114tb
ComPute4
oritioal
buckling
load
eerved
ob itioal
buckling
load
2:TIL4
(4)
(2)
(8)
(7)
In.
Lb.
Thick/eel
(1)
Average proportional
limit ...... In
(3)
In.
(2)
It 460 to face grain
(Cocoons 0 4 P)
proper.
nous'
C.
limit
(8)
ILE
k o ebverse4
k ey
(10)
nith
grain
parallel to
span {Coupons
1)
12.00
9.47
0.065
le
12.00
9.49
.066
If
12.00
9.49
.066
51
lr
14.04
9.54
.063
39
75
1.523
1.178 846
1.48/
1.189 766
1.679
1.144
1,338
1.000 lb.
1,656.0
1.2..‘27a,
124.2
130.6
1,395
874
0)
"LVIL.
Ho.
824
48
Id
*
(33)
(211
Lb. per so. in,
with Laos grain
parpendioular
span (Conveneto
1,350
1,524.0
138.9
2.200
1,275
1,276.5
140.3
140.3
lre
8.02
2.54
.065
56
140
978
.959
1.804
3.739
1.577
1.276.5
2d
14.01
9.49
.146
672
750
1,900
1.771
1.128
1.259
1,371
2,136.0
162.2
2e
12.01
9.49
.144
655
675
2,151
1.522
1.179
1.216
1,574
2,104.0
155.4
2f
12.00
9.49
.147
670
1,705
1.554
1.170 1,222
2,200.0
136.8
3d
12.00
9.49
.183
1.544
1,450
2,568
1.502
1.182
1.111
1,473
2,295.0
187.9
30
12.00
9.49
.183
1,565
1,550
2,747
1.521
1.179
1.168
1,582
2,448.0
182.7
3f
12.00
9.50
.182
1,493
1,440
2,656
1.485
1.188
1.146
1,536
2,160.0
193.2
3r
14.06
9.52
.171
1,097
1,240
1,784
1.720
1.137
1.284
1,096
1,940.0
185.8
ire
8.02
9.54
.175
1,531
1,400
1,846
.979
1.482
1.356
1,106
1,940.0
185.8
4r
11.04
9.53
.066
42
85
748
1.399
1.214
2.467
1,190
1.381.0
99.9
Ore
8.03
9.54
.064
45
125
821
1.016
1.444
3.981
1,344
1,381.0
99.9
50.
12.00
9.49
.152
726
1,807
1.483
1.188 1,253
1,786.0
162.0
5e
12.00
9.49
.143
556
1,881
1.515
1.180 1.386
1,787.0
138.0
5f
12.00
9.49
.142
543
1,443
1.521
1.179 1,071
1.818.0
135.0
6r
14.02
9.53
.183
1,039
950
1,385
1.793
1.124
1.028
794
1,790.5
119.6
Sre
8.00
9.51
.181
1,286
1,070
924
1.024
1.436
1.194
537
1,790.5
119.6
8d
12.00
9.49
.143
642
2,125
1.535
1.176 1,566
2,173.0
151.5
8e
12.00
9.50
.144
666
2,172
1.513
1.180 1,588
2,098.0
161.6
8f
12.00
9.49
.144
693
1,900
1.487
1.187 1,390
2,032.0
179.4
lOr
14.04
9.53
.063
47
125
1.112
1.816
1.122
2.991
1,852
2,081.0
125.0
lOrm
8.02
9.55
.062
57
125
778
1.035
1.426
3.145
1,314
2,081.0
125.0
lld
12.01
9.49
.144
674
2,057
1.528
1.17/ 1.505
2,184.0
159.2
709
2,163
1.522
1.179 1,572
2,215.0
168.0
640
2,255
1.565
1.168 1,650
2,294.0
136.7
lle
12.02
9.49
.145
lit
12.00
9.49
.144
Ilr
10.79
9.54
.146
696
740
1,641
1.378
1.221
1.300
1,178
2,173.5
146.8
11rs
8.01
9.53
.147
835
800
1,205
1.024
1.436
1.375
860
2,173.5
146.8
12r
8.95
9.53
.185
1,413
1,300
1,670
1.108
1.362
1.254
947
1,722.5
150.6
12re
8.01
9.53
.183
1,475
1,600
2,166
.991
1.470
1.594
1,242
1,722.5
150.6
134
12.62
9.49
.110
501
425
2,087
1.398
1.213
1.030
1,999
1,672.0
496.0
13.1
12.82
9.49
.109
522
525
2,286
1.392
1.215
1.223
2,210
1,712.0
501.0
13f
11.62
9.49
.109
527
1,992
1.263
1.267 1,926
1,683.0
526.0
146
12.82
9.49
.251
6,140
4,630
4,068
1.397
1.213
.915
1,708
1,703.0
518.0
14e
11.25
9.50
.247
6,274
4,600
4.834
1.234
1.282
.940
2,060
1,836.0
001.0
14f
11.25
9.49
.252
6,066
4,500
4,544
1.234
1.288
.981
1,900
1.658.0
458.0
4.699
1.389
1.216 1,638
1,500.0
503.0
4.668
1.218
1.291
1,625
1,522.0
525.0
5,384
1.214
1.293 1.860
1,460.0
544.0
3,602
1.400
1.213
1.253
1,866.0
535.0
154
12.82
9.50
.302
9,939
15e
11.25
9.49
.304
11.087
15f
11.25
9.49
.305
11,213
15r
12.85
9.82
.302
11.313
5,000
6,000
.582
.643
Sheet 3 of 4
Z K 49089 F
fo
table 15.--
bU
test •
la
s and
o
ne
Propertiso of plats material
Compression buckling teat plates
Average proportional
limit etre.. in
comprossion
Loaded at 450 to direction of tam/ grain
Panel
no.
/one&
Width
Th141:nee!
Computed
critical
buckling
load •
Ob••t9.6
or/ U. col
buckling
1444
Computed
load at
Proper-
At
:0 observed
1.14441
45° to taus grain
(Coupons 0 k P)
Z.!
'44
limit
12) ...
•ntinu
(9)
(10)
(211
Average modulus of elasticity
In bonding
With tooe grain
parallel to
span (Coupons
D k 5)
(22)
With face groin
perpendicular to
span (Coupons
p & a)
(23)
(2)
(3)
(41
Isa
ISA
ISA
li
"91112'
ler
12.84
9.50
0.106
286
215
638
1.424
1.205
1.327
640
1,255.0
297.2
/7d
11.33
9.49
.240
3.973
2,400
&Om
1.230
1.286
.938
1,255
1,252.0
372.0
17e
11.25
9.48
.240
4,171
2,745
1.221
1.200 1,208
1,180.0
395.0
27f
11.25
9.49
.240
3,772
3,109
1.216
1.292 1,365
1,041.0
366.0
17r
12.82
9.50
.245
4,857
2,750
1.606
1.400
1.213
.694
690
1,477.0
425.5
16,
12.67
9.51
.302
7,606
4,200
2,010
1.405
1.211
.669
702
1,423.6
325.0
20d
22.25
9.49
.236
5.499
1,700
3.304
1.230
1.286
.866
1,511
1,768.0
517.0
206
11.25
9.49
.2113
5,512
3,500
3,598
1.232
1.284
.885
1,593
1,776.0
495.0
20f
12.83
9.21
.230
4.623
1,466
1.765.0
520.0
23d
11.25
9.49
.244
5.407
3.600
0.413
1.247
1.277
.850
1,486
1,828.0
431.0
23e
11.25
9.49
.241
5.710
3,700
3.239
1.249
1.276
.826
1.416
1.966.0
460.0
23f
11.25
9.49
.242
0,642
3.600
5.224
1.243
1.279
.831
1,404
1,816.0
452.0
23r
12.84
9.52
.243
5,273
4,000
2,391
1.400
1.213
.920
1.036
1.674.0
478.0
24r
12.82
9.51
.504
0,756
4,180
2.322
1.456
1.201
.560
798
1,627.5
347.0
256
12.00
9.50
.110
509
2,257
1.302
1.250 2,160
1,564.0
514.0
25s
12.00
9.50
.112
560
540
1.302
1.260
1.204
2,132
1,632.0
536.0
25f
12.01
9.52
.110
504
520
1.094
1.290
1.257
1.372
1,904
1,424.0
544.0
26d
12.00
9.51
.244
6,147
3.959
1.307
1.247 1,706
1,856.0
538.0
26e
12.02
9.50
.244
6,562
1.576
1.309
1.246 1.672
1.956.0
581.0
26f
12.03
9.61
.244
6,195
3,680
1.312
1.244 1.586
1,886.0
542.0
274
12.00
9.51
.305
10,473
4,902
1.288
1.258
1,690
1,356.0
538.0
11,256
6,474
1.289
1.257 1,881
1,398.0
549.0
(1)
(8)
(7)
(
pep 40. fn.
5,981
.708
2.009 15.
27e
12.01
9.51
.306
27f
12.01
9.52
.505
9,061
4.721
1.296
1.252 1,628
1,394.0
484.0
29d
12.02
9.51
.247
5.739
2,647
1.295
1.220
1,127
1,473.0
536.0
29e
12.01
9.52
.236
4,880
5.029
1.303
1.249 1.348
1,579.0
484.0
29f
12.02
9.50
.216
4.542
2,641
1.315
1.243
1.183
1.563.0
440.0
3.410
1.297
1.001
1.493
1,686.0
580.0
3.202
1.294
1.253
2,397
1,641.0
628.0
2.840
1.336
1.257 1.290
1. 726.0
562.0
32d
12.00
9.50
.241
5.917
32e
12.03
9.51
.741
6.107
5.757
2,150
4.000
.062
.821
32f
12.01
9.25
.238
35d
12.02
9.51
.242
5.234
3,800
2.122
1.331
1.238
.004
1,184
1,815.0
435.0
35e
12.01
9.50
.239
4.004
3.400
2,931
1.340
1.236
.057
2,291
1,874.0
404.0
35f
12.00
9.52
.241
5,180
3,700
3,228
1.325
1.240
.aaa
1,407
1,791.0
440.0
tr is the ratio of the length of the plots (0) to the halt wove length (b . ) of an infinitely long plate of the same construotion and width.
X.
is the ratio of the value of the tooter (k.) of formula (21) for • plats of length (8) to the value of this factor for an infinitely long plate (k.)
s„. of the same construction and width.
kc
observed
I
(0.) of tottoulo (6) for a plots of length (0) to the value of this factor for an infinitely long
is Lb. ratio of the test cola* of the f ) of the some construction and width.
plate
cc.
Sheet 4 of 4
49090 r
LEGEND:
Am 5 . PLATE FOR BUCKLING TEST; FACE GRAIN AT
45° TO THE LOADED EDGES AND TO THE DIRECTION OF THE LOAD.
D AND E COUPONS FOR STATIC BENDING TEST, FACE
GRAIN PARALLEL TO SPAN.
F AND 0 COUPONS FOR STATIC BENDING TEST, FACE
GRAIN PERPENDICULAR TO SPAN.
0 AND P COUPONS FOR PACK COMPRESSION TEST, FACE
GRAIN AT 45° TO LOAD.
A SO° PLATE FOR BUCKLING TEST, FACE GRAIN AT
30° TO THE LOADED EDGES, OR 60° TO THE
DIRECTION OF LOAD.
A so .
PLATE FOR BUCKLING TEST, FACE GRAIN AT
60° TO THE LOADED EDGES, OR 30° TO THE
DIRECTION OF THE LOAD.
AND E COUPONS FOR STATIC BENDING TEST, FACE
GRAIN PARALLEL TO SPAN.
F AND 8 COUPONS FOR STATIC BENDING TEST, FACE
GRAIN PERPENDICULAR TO SPAN.
M AND N COUPONS FOR PACK COMPRESSION TEST, FACE
GRAIN AT 60° TO LOAD.
0 AND P COUPONS FOR PACK COMPRESSION TEST, FACE
GRAIN AT 30° TO LOAD.
A 15.
PLATE FOR BUCKLING TEST, FACE GRAIN AT
IS° TO THE LOADED EDGES, OR 75' TO THE
DIRECTION OF LOAD.
A75° PLATE FOR SUCKLING TEST, FACE GRAIN AT
75" TO THE LOADED EDGES, OR 15' TO THE
DIRECTION OF LOAD.
0 AND E COUPONS FOR STATIC BENDING TEST, FACE
GRAIN PARALLEL TO SPAN.
F AND 0 COUPONS FOR STATIC BENDING . TEST, FACE
GRAIN PERPENDICULAR TO SPAN.
14 AND N COUPONS FOR PACK COMPRESSION TEST, FACE
GRAIN AT . 75' TO LOAD.
0 AND P COUPONS FOR PACK COMPRESSION TEST, FACE
GRAIN AT . I6° TO LOAD.
Figure 91. -Layout of plate specimens and coupons on panels.
Z ll 41732S 7
C:I•
C:0
CZ0
(Z.
.n:1
CI
•Z)
C:lo
41
N
c0
Ni.
n
fr)c CI
'n 1
t:i
0
N N
•to
......
(Caitin ad) OVO
7
N
tb
CZI
N
......
O
O
A
cu
0
08
c
o
0.
11
0
o°
0
04
oo
0
n0 0.
02
0
0
0
02
COMPUTED
0.4
0.6
08
CRITICAL LOAD/COMPUTED
/2
/0
/4
/6
PROPORTIONAL LIMIT LOAD
Figure O3.--Observed critical load plotted against the computed critical load, both expressed as ratios to
computed proportional limit load. kcik" assumed equal to k s /kso, in computing critical
load. Compression at 15° to face grain.
/.2
0
0
0
-w
0
0
te
0
0
02
0. 4
a6
0.8
/0
12
1 6
Id
COMPUTED CRITICAL LOAD/ COMPUTED PROPORT/ONAL LIMIT LOAD
Figure 04.--Observed critical load plotted against the computed critical load, both expressed as ratios to computed proportional
limit load. ke/ke . assumed equal to k./ksw in computing critical load. Compression at 10° to face grain.
Z 11
48927 F
20
/4
/1
C • , •
( 00
•
v
40
0
/0
a
0
06
00
0
0
0
D
0
04
02
0
1.8
1.4
1.2
/.0
0.6
COMPUTED CRITICAL LOAD/ COMPUTED PROPORTIONAL LIMIT MAD
0
02
04
o
2q
Figure 95...-Observed critical load plotted against the computed critical load, both cap eeeee d as ratios to computed proportional
in computing critical load. Compression at 45° to face grain.
limit load. Ir Ar . assumed equal to k /It
c
i io
Nv
II)
e/
78
/
,
2‘
0
%
0:f
22
n
0
/
0
42
o°
04
00
04
1.0
12
/4
/0
COMPUTED CR/T./CAL LOAD/ COMPUTED PROPORT/ONAL LIMIT MAD
d as ratios to computed
Figure 96.--Observed critical load plotted against the computed critical load, both sop proportional limit load. kik.. assumed equal to k",. In computing critical load. Compression at
60° to face grain.
ZM
48928 F
/4
/.0
0
0
0
.43
0
0
0
0
0
0
0
0
0
0 0
02
04
a6
/4
/4
08
66
COMPUTED CRITICAL LOAD/ COMPUTED PROPORTIONAL L/M/T LOAD
Figure 97.—Observed critical load plotted against the computed critical load, both sap
d as ratios to computed proportional
limit load. k e /ko . assumed equal to ki /k.. in computing critical load. Compression at 75° to face grain.
20
1
1
I
i
\ LEGEND
0 OBSERVED VALUES OF kor .
\
1
---%
—RECOMMENDED CURVE FOR A.c/frG o0
n
\ — —kV, CURVE FROM FIG /2 (MIMED 1316)
nsoo
0
I
18
1
\\:„.......„....................„"____
\ \o
o
\
o
0
o n
•....„
•n
° oA
•n
-......„ ,
r... -..
o0
oo
---
0o
06
0.6
Z M
489E 9 p
0.8
1.0
1.2
b/bl
/4
—r__
—
20
Figure 98.--Observed values of ko/kcco , recommended curve for ice/k., and curve for k./h,..
for comp
at 15°to face grain.
2.0
10
I,
I
I
\ L EGEILI
‘
o OBSERVED VALUES OF Ifc/Arc
18
I
\ — RECOMMENDED CURVE FOR kihco.
\-•-•.-1/3//r CURVE FROM F/G.12(41/ME0 a/6)
1.6
1
\ a
\
8
13\ \
14
n -,..
o
€
a
8 4.2
--. n
-....,..___
-._
0
10
06
04
04
/2
/0
1.4
t6
/.8
20
6/il
Figure 99.--Observed values of t e/ko ., recommended curve for k./k.., and curve for
comp lllll on at 90° to fit)* S.A. n
for
2.0
1.6
/4
—I.
8
1/4
/4
aa
0
0
0
•e
8
0
0
0
12
0
0
0
1/44
C
1.0
08
0. 6
0b
0.8
1.0
14
/2
46
It?
29
b/br
Figure 100.--Observed values of k.Are., roommended curve for k e/ko ., and ourve for 9/k.. ror
empresolon at 46° to time grain.
Z
V489307
LEGE/OD:
o OBSERVED VALUES Of /cc/1(c°,
1a
II\
—RECOMMENDED CURVE FOR /rchrcoo
mp:.
him
liniagn
II
•
•
\
16
8
CURVE PROM F/6.12 (N/NEO)
--1r34
'
.
12
8
x)
I
14
as
II&
MI
0.6
Re
/2
/6
le
2r)
b/s
Figure 101.—Observed values of Irc/k.., recommended curve for Iro/ko ., and curve for
for
compression at 80° to face grain.
2.0
\
\ LEGEND:
1
e 055ERVEO VALUES Or "r5,4
\
— RECOMMENDED CURVE FOR /r c/
nr 00
CURVE .FROM FIG r2 OwpfE0 /NO
\ \--11:34
ri A
8 /.6
<
0 4k
0 N
8
k.0
0
..,..
....
1.2
v
CO
0
.....
0
......
=
-...-
00
0
0.8
cb
05
A1.0
1.2
/4
/0
2.0
Yb'
Figure 102.--Observed values of
k c /kcm, recommended
compression at 75° to face grain.
Z M 48931 F
curve for Ilk„., and curve for Ir./k. "
for
2.0
/.8
1.6
8
/4
N •
1.0
0.8
0.6
0.4
0.8
1.0
1.2
bib/
/4
/6
/8
20
Figure 103.--Values of ke ike . corrected to agree with, observed data for compression at various angles
to face grain.
/.0
O
0
0
O
0
0
o ,.0
7
0
0•
ZO
/ 2
Z4
02
0
0406
COMPUTED CRITICAL LOAD/ COMPUTED PROPORTIONAL LIMIT LOAD
Figure 104.--W e/ice . determined by correcting
at 15° to face grain.
Z M 489:52 'F
k./k..
in computing critical load for compression
O
p
0
0
10
0k
O
er
0
O
'1 08
`4
t
‘.3
04
W
Lk1
cC1
0k
k 02
L.)
0
0
06
0.4
/0
/.2
06
/4
COMPUTED CRITICAL LOAD/ COMPUTED PROPORTIONAL LIMIT LOAD
02
20
Figure 105.--k./k ow determined by correcting k./k s . in computing critical load for compression at 30° to face grain.
1.0
O
0
0
o
0
0
0
04
06
48
/.0
/4
12
COMPUTED CRITICAL LOAD/ COMPUTED PROPORT/ONAL LIMIT LOAD
Figure 106.--k./ke. determined by correcting
to face grain.
Z M 48933 F
/6
ks/ks m in computing critical load for compression at 60°
CO
••nn:.
ri
S.
▪
bp
Z
O
0
03
V
Cm
%ID k
0
4.)
o
I0
,_
.1
4J
cd
=0
3
3i
0
• V
at
t.
P.
E
0
0
k
t
N
k
t.
0
o°.
irl
ck
r-i
r-i
id
U
1-1
.o
144
04-1
•....:
K
,..
+2
hh
CO C j
CZi •-...,.....,..
0
I*
0
0
P.
E
0
o
=
..-1
LZ
.f4(8
moo
'
%
nI
.W
44 .1
b0
CS
yl
44
V
‘,J,
0
0
S.
h
t.
0
0
b.,
.0
V
1U
.
S
N
0
1;
J
4.;
t0
•t:1
cv lk
Ci
01/07 .1/W17 7VNO/IYOGIOcYci 021nciA30.9
/00#07 7 b'..7/10/.7 074,Y75-£70
e..,
0
8
Q0