Column and plate compressive strengths of aircraft structural materials extruded 75S-T aluminum-alloy

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Material Information

Title:
Column and plate compressive strengths of aircraft structural materials extruded 75S-T aluminum-alloy
Series Title:
NACA WR
Alternate Title:
NACA wartime reports
Physical Description:
11 p., 12 leaves : ill. ; 28 cm.
Language:
English
Creator:
Heimerl, George J
Roy, J. Albert
Langley Aeronautical Laboratory
United States -- National Advisory Committee for Aeronautics
Publisher:
Langley Memorial Aeronautical Laboratory
Place of Publication:
Langley Field, VA
Publication Date:

Subjects

Subjects / Keywords:
Airplanes -- Testing   ( lcsh )
Aerodynamics -- Research   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
Summary: Column and plate compressive strengths of extruded 75S-T aluminum-alloy sheet were determined both within and beyond the elastic range from tests of thin-strip columns and from local-instability tests of H-, Z- and channel-section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results, which are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures, supersede preliminary results published previously.
Bibliography:
Includes bibliographic references (p. 7).
Statement of Responsibility:
by George J. Heimerl and J. Albert Roy.
General Note:
"Originally issued July 1945 as Advance Restricted Report L5F08a."
General Note:
"NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance research results to an authorized group requiring them for the war effort. They were previously held under a security status but are now unclassified. Some of these reports were not technically edited. All have been reproduced without change in order to expedite general distribution."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 003807482
oclc - 126869441
System ID:
AA00009371:00001


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ARE No. L5F08a


NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS





lWAlTIME IREJPORT
ORIGINALLY ISSUED
July 1945 as
Advance Restricted Report L5FOBa

COLUMN AND PLATE COMPRESSIVE STRENGTHS
OF AIRCRAFT STRUCTURAL MATERIALS

EXTRUDED 75S-T ALUMINUM ALLOY
By George J. Heimerl and J. Albert Roy

Langley Memorial Aeronautical Laboratory
Langley Field, Va.
UNIVERSITY OF FLORIDA.
DOCUMENTS DEFP'RTi 'i T
,120 M.FSTC SC;ECE IBF;, R''
P.O BO. 11701 1
GA",NESVILLE, FL 32611-7011 UI'SA



NACA


WASHINGTON

NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of
advance research results to an authorized group requiring them for the war effort. They were pre-
viously held under a security status but are now unclassified. Some of these reports were not tech-
nically edited. All have been reproduced without change in order to expedite general distribution.
L 173




































Digitized by the Internet Archive
in 2011 with funding from
University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation


http://www.archive.org/details/columnplatecomlang




: C :


NACA ARR No. L5Fo8a


"tTICTP ADVISOCRY COMMITTEE FOR AEROCI TICS


ADVA"Z:::; R7STRIC ?-) RT"CRT

COT .1D PT.ATE CC ~RFSSIVE STR~T-TFS
CO IRCR^FT STRUCTUTT7RALT "'TERIA.S

FXTRT'DFD 75S-T AT''i-': ALLOY

By George J. Teimnerl and J. Albert Roy





Colum~r and plate comeressive strengths of extruded
75S-T aluminum alloy were determined both within and
beyond the elastic range from tests of thin-strip columns
and iocal-i nstabl it tests of H-, Z-, and channel-
section colun s. These tests are sart of an extensive
research investigation to provide data on the structural
strength of various aircraft materials. The results,
which are presented. in the form of curves and charts that
are suitable for use in the design and analysis of air-
craft structures, supersede preliminary results published
previously.


lj'CDTT0MjOY


Column and plate members in an aircraft structure
are the basic elements that fail. bT instabilit. For the
design of lightweight, structurally efficient aircraft,
the strength of these elements must be known for the
various aircraft materials. An extensive research program
has therefore been undertaken at the Langley Mlemorial
Aeronautical Laboratcry to establish the column and plate
compressive strengths of a number of the alloys available
for use in aircraft structures. Parts of this investiga-
tion already completed are given for 24S-T and 17S-T
alumninum-alloy sheet in references 1 and 2, respectively.

The results of tests to determine the column and
plate compressive strengths of extruded 75S-T aluminum
alloy,which supersede preliminary results published in
reference 7, are presented herein.










:r'CA ARR. Ilo. T1FOSa


S'-,; PT,S


L length of column

p radius of ;-rstion

c fixity coefficient used in Fuler column formula

L effective slenderness ratio of thinr-stri'? column

bI, tF width and thickness, respectively, cf flI'rge of
H-, Z-, or channel section (se fi-. 1)

bi, tW width and t4ickness, resoecfiv-il, o-f web cf H-,
Z-, or channel section (see i.... 1)

r corner radios (see fig. 1)

k.- nondimensionel coefficient used vith b 9, nrd t,..
in plate-bu.klirr.r formula (.? fi,:.. 2 a'.d 3
and reference i.)

Ec modulus of elasticity in coc;r c', n, taken as
10,500 ksi for extruded 755-T Eli ^inu:.i"l alley

T nondinensional coefficient (T1-j, v-l i3 cf T is
so determined tjhat, when the effeccrive mnouulus
T7E is substituted for Ec in the equation
for elastic buckling of colunus, the computed
critical stress agrees with the experimentally
observed value. The coefficient T is equal
to uniV', within the elastic rn,.e and j-creasEc
with increasing stress iL.ocnd the -.lestic ran-e.)

Snondimensional coefficient for compr-essed ,plates
corresocndine to T for columns

JL Poisson's rntio, taken as.0.5 for extruded
75-T aluminum alloy

cr critical compressive stress

max ave:'n.' e compressive stress at maximum load


comoressive yield stress


o-'










ITIACA ARR No. 15FO1a


METHOD2 CT TUST'TIT AND ANAITSIS


A'l tests were made in r.al c testing 3machi ns
-'r Ite within three-fourths of 1 percent. The methods
t.,-' tirg and analysis Geveloped for this research
-. r-.n m ere described in reference 1 and may be briefly
s :r -riz.ed as follows:

The comiressive stress-strain curves, which identify
the material for correlation with its column end pl2te
ce :.;:rssjve strengths, were obtained for the with-grain
direction from tssts of single-thiclness compression s eci-
rm- c cut from the extrided E-sections. These tests were
-:.'- in a compression fixture of the '.-ntgomery-Templin
" '-, which provides .lateral supr ort throu:;h closely
.rr:-. 2 rollers.

The column strength and th associated effective
e'-lu ai modulus were obtained for the with-grain direction
I--: t.-- use of the method presentcec in reference 5, in
'ir.: t.in-strip columrus of the r:isterial were tested with
*-: ids clanped in fixtues that prov ide a high degree
of -P..1 restraint. The fixtures used hsve been irproo'ed
r.d tne method of analysis has been nod"ified since p'ubli-
r._ ti:.n of reference 5. The method now. used results in a
ci: I u. curve that is representsati.ve of nearly perfect
c l i specimens. In addition, the method now takes into
a.-cC. t the fact that columns of the dimensions tested
ar- actuallyy plates with two free ed-es. These columns
:r; cut from the flanges of the extruded H-section
e,-.,?ent to the junction of the web and flange.

The plate compressive. strength of the material was
.Lt..ed from compression tests of H-, Z-, and channel-
S t'_n columns so pronortioned as to develop local
is -ility, that i, inst-ablity. of the plate elements.
K(,,- fig. p.) The extruded '-sect "ns were obtained in
t.r-. different web widths; the flange widths of each were
'T3r. by killing off parts of the flanges. a,-,, flanges
cf 3-,:'.e of the H-section ey7trusions were removed in such
a :" as to make both Z- and channel sections. The flange
.lidt_3 of the Z- and channel-section columns were varied
i. t:.e same manner as the flanre widtr s for the H-section
ccl';ns. The lengths of the columns vwere selected in
acc-riance with the principles s-t forth in reference 6.
Th. columns were tested with the ends ground flat and
squ.r', and bearing directl-y against the tcsting-machine










S4 ''A-A ARR :ro. L5FO8a


heads. In these local-instability tests measurements were
taken of the cross-sectional distortion, and the critical
stress vwas determined as the stress at the point near the
too of the knee of :., stress-distortion curve at which a
marked increase in distortion first occurred with small
increase in stress.

A difference in the anal.-Sis presented herein from
that employed in reference 1 is concerned with the
measurement of bF and b,.~ for use in evaluatirng ocr
by means of the equations and curves of figures 2 and 5.
In the theoretical derivation of the clate-buckling for-
mula mathematically idesli zed sections were assumed, in
which the effects of the thi i: .ss of the fl-:.' and web
plate elements and the effect of the corner condition -
square, curved, or fillet were neJlected in establishing
the widths of the ateata elements. Consequently, as the
experimental investi-.tion of the elate compressive
strength of aircraft materials projl sses, some arbitrary
dimensi .'-'r: of the flange and web widths has been found
necessL- in order that the theoretical and experimental
buckle. stresses i r, within the elastic range. In the
formed Z- and channel sections of references 1 and 2 with
inside bend radius of three times the sheet thickness, the
widths of the- flange and web were defined by center-line
widths with square corners assumed. In the extruded
sections with small fillets ronorted herein, the widths
of the flarge ard web ware defined by the inside face
dimensions, as shcvn in figure 1.


S"-1LTS AND DTSCi.'3IC

Compressive Stress-Strain Curves


Cominressive stress-strain curves for extruded 75S-T
aluminum alloy, which were selected as typical or average
curves for the column material, are given in figure 5.
These curves were obtained from tests of compression
specimens cut from the '!ddle part of the flanges of the
extrusions as shown in fi: r, 5.

In order to st'C,-, the variation of the c,--rressive
properties over the cross section of an E-section extru-
sion, $ "..ris were made by tests of compression specimens
cut from the web and flanges of the H-sections. The










1',Ur .RP: To. L,5 OSa


vaisZtion of the compressive yield stress Gcy over the
c -..sr section is shown in fi-. rI- o. Values of a, at
t-, outer oart of the flanges were generally higher than
th: e for the inner part of the flarges; the lowest value
f JOy was found in the web in all cases. The stress-
'scrain curves of figure 5, representative of the material
in the middle part of the flanges, are therefore usually
tr ':-al or average curves for the flange material and show
v..- s of aoy that are unconservative in comparison with
v.l.ies of the compressive yield stress for the material
.-. t"he web.

The thin-strip or T-, Z-, and channel-section columns
to '."Ylich a particular stress-strain curve applies are
!i-,.`.i.ated in table 1 together with the values of acy for
tlc-t stress-strain curve, The values of ocy have an
a~cr-,ge of about 79 ksi for the with-grain direction.
TI:e -odulus of elasticity in compression was taken as
i;,..O0 ksi, the present accepted. value for extruded 75S-T
l' .inunm alloy.


Col. un and plate Cc.' ressive Strengths

Because the comorossive properties of an extruded
al..ir num alloy m .ay -..- considerably, the data and charts
c'f rIis report should not be used for design purposes for
:.-.riTsions of 75S-T aluminum alloy that have appreciably
iff -rent compressive properties from those reported
h-: r-.n, unless a suitable method is devised for adjusting
t rst results to account for variations in mat-rial
-_ro .rties. The results of the column and local-instability
t-st- of the extruded 75S-T aluminum alloy are summarized
_-.r .in; a. discussion of the basic "relationships is given
in r -ferance 1.

Column strength.- The column curve of figure 7 shows
the results of tests of thin-stri columns loaded in the
v. it. grain direction. The reduction of the effective
,'U.0 :' us of elasticity TEc with the increase in column
st:--s is indicated by the variation of T with stress
shc";. in figure 8.

Plate coipressive strength.- The results of the local-
inrt ability tests of the H-, Z-, and channel-section
coil~ons used to determine the plate compzressive strength









NACA ARR No. L5F08a


are given in tables 2, 3, and 4, re-oectively. The plate-
buckling curves, analogous to the column curve of figure 7,
are shown in figure 9. The reduction of the effective
modulus of elasticity rT1c with the increase in stress
for plates is indicated by the variation of r with stress,
which is shown together with the curve for T, in figure 8.
In this figure, the T-curve does not cross the -r-curves as
it did for 24S-T aluminum alloy. (See fig. 12 of refer-
ence 1.) The extruded H-, Z-, and channel-section columns
of 75S-T aluminum alloy apparently were more nearly perfect
than the formed Z- and channel-section columns of 24S-T
aluminum alloy (reference 1), so that the r-curves for the
extruded 75S-T aluminum-allcy columns diverge from unity
at about the same point as the T-curve, which is repre-
sentative of nearly perfect columns.

The variation of the actual critical stress acr with
the theoretical critical stress acr/r computed for
elastic buckling b- means of the formulas and curves of
fimi es 2 and 5 is shown in fiu--- 10. In order to illus-
trate the difference between the critical stress acr
end the average stress at maximum load Omax, the varia-
tion of Ocr with Gcr/~max is shown in figure 11.
Because values of amax may be required in strength cal-
culations, the variation of amax with (cr/T) is pre-
sented in figure 12.

Figures 9 to 12 show that the deta for H-sections
described curves different from those indicated for Z-
and channel sections. One of the reasons why higher
values of max were obtained for the H-sections than
for the Z- and channel sections for a given value of ocr/y,
(fig. 12) may be the fact that the high-strength material
in the flanges forms a higher percentage of the total
cross-sectional area for the H-section than for the Z- or
channel section. For the H-section, mrax is increased
over the value for the Z- or channel section for the
entire stress range covered in these tests (fig. 12);
Ocr for the F-section, however, is increased only for
stresses beyond the elastic ra:.ge (fig. 10).

For the variation of Gccr with Ocr/rmax (fig. 11)
and of Omax with ocr/r (fig. 12), only a single curve
is required for a given t:-,e of cross section regardless
of the value of br/t-;-: whereas, in the corresponding
figures 15 and 16 of reference 1, re:-arate curves were









NACA AR 7o. 10 r7058a 7


nl:?esary for different values of this ratio. This dis-
t ,Ction is probably due to the fact that there is no
i:-cease in the conuoressive yield. stress in the corners
. t :e extruded sections co, arablee with the increase in
t'-e rirn-ers of forced specimens caused by the cold work
- r -_., r the saopes from flst sleet, Reference I shows
Sthe increased strength in the curved corners due to
f.r... -" might produce a variation in the average stress
ot :.*ximum load when by"/t. is varied.


L. n:lsy Memorial Aeron-autical Laboratory
'Jational Advise~-- Committee for Aeronautics
T :-cley Field, Va.





1. Lundquist, .ene ., Schuistte, Even H., Heimerl,
George J., and Roy, J. Albert: Column and Plate
Compressive Stren ngbs of Aircraft Structursl
I- terials. 21;.-T A' uir.inur.-Alloy Sheet.
NACA ARR I;o. TLF01, 3 95.

:. himerl, George J., and Roy, J. Albert: Column and
Plte Compressive Strengths of Aircraft Structural
Taoterials. 17S-T Aurrinumri-Alloy Sheet.
AiA AR iTo. L FOS 1 5

eimrl, CGeorge J., and Roy, J. Albert: Column and
Plate Compressive Strength- of Extruded XB75S-T
Aluminum Alloy. 1ACA R3 ro. 1.4 26, 1941 -.

14. -l.oll, 7'. D., Fisher, Cordon P., and TIl.merl, George J.:
Charts for Calculation of the Critical Stress for
local Instability of Columns with T-, Z-, Channel,
and Rect.-. r.,I r-Tube Section. NACA 'RR ~. 3i14,
1.9i5 .

5. Lundquist, Eugene E., Fossmen, Carl A., and Koubolt,
John C.: A IJethod for Determ ninin the Column Curve
from Tests of Columns w-ith .ial Restraints against
Rotation on the Ends. NACA TN No. 903, 1945.

6. Femerli, Geor'- J., and Roy, J, .Albert: Determination
of Desirable L.eniths of Z- and Channel-Section
Columns for Local-Instability T--sts. "fAA RB
No. LL4HIO, 10 '..









TA nL7 1


NACA ARR "o. L5FO8a


CCr SIT V ~PROr"TTIS OF T-''T'ID"TD 75S-T AIT"'I:"T.T ALLOY

i[ = 10,500 ksil


Columns to which stress-strain
curves apply


Tvyoe


Thin strip

H



H

H

H




z

z
Z

Z


z

.7
Z


Channel

Channel



Channe 1

i".ii'l 1


Designation
(tables 2 to L,)


All

la tc 7b, 5a to 5c,
7a to 1b, 10 to llc

15a to 17c

1?a to 2e'a

23b, 25c

4a to '4c, 6a to 6c,
9a to 0o, 12a to 2ci

la to b

Ia, kb, b

5a, 6a to 6c

7a to C8b

9a to 9c

la to 3c


!la to 5c

6a to 6c

7a to 8e


Stress-
strain
curve
(fig. 5)1


A

B




D

E
r?


G

HI

I

E

A

G

H

I



A


Comoressive ield!
stress, Ocy
(ksi)


77.5

78.6


81.6

79.3

79.1

78.1


79.1

78.4

78.7

79.1

77.5

79.1

78.4

78.7

77.5

77.5


NATIONAL 'T"TSCrY
CC!7W'TT>, PCR A'-RO'.'ITTICS










NAMA ARR No. L5FO8a 9


TAaEE 2.- DIMENSIONS AND TEST RESULTS FOR H-SECTION COLUMNS
THAT DEVELOP LOCAL INSTABILITY



Column i tp bw L L1 bW by 1 g
o n tr p T; V kW 1 or 77max
(In.) (In.) (in i in.) (fig. 2) (kal) (kl) (ksl)
(a)


15a
15b


16b
164c
157
15b
150
16a
16b
16e
172
27b
17C

i2e

19a
21b
19c
20a
22b
20c
21a
21b

22b
-2b
25a
2b
25c


0.220
.121
.120
.120
.120
.121
.121
.120
.121
.121
.121
.120
.120
.121
.121
.121
.121
.121
.121
.120
.121
.121
.121
.120
.121
.121
.121
.121
121
.120
.120

.120
.119
.119
.119
.119
.119
.119
.119
.119
.119
.119
.119
.119
.120
.119

.125
.123
.122
.125
.122
.122
.122
.122
.122
.122
.122
.122
.122
.122
.125
.124


3.126
.126
.126
.126
.126
.126
.126
.121
.121
.121
.126
.126
.126
.121
.122
.121
.126
.126
.126
.126
.126
.121
.121
.121
.126
.127
.127
.127
.122
.121
.122

.125
.125
.123
.123
.125
.123
.123
.125
.123
.125
.125
.125
.125
.125
.125

.121
.121
.121
.121
.120
.119
.120
.120
.119
.120
.120
.120
.119
.120
.122
.122


1.61
1.61
1.62
1.61
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.62
1.61
1.62
1.62
1.62
1.62
1.62
1.61
.61.
1.61
1.62
1.62
1.62

2.23
2.23
2.23
2.21
2.23
2.25
2.24
2.25
2.25
2.23
2.23
2. 2
2.23
2.24


2.74
2.74
2.71
2.74
2.74
2.7
2.74
2.74
2.714
2.74
2. 74
2.74
2. 74
2.74


0.82
.80
.82
.90
.90
.98
.99
.99
.99
.99
1.03
1.05
1.03
1.08

1.16
1.17
1.18
1.16
1.17
1.17
1.17
1.17
1.25
1.34
1. 5
1.34
1.34
1. 34

1.26
1.26
1.26
1.56
1.57
1.3
1.45
1.43
1.60
1.59

1.9



1.6
1.24
1.14
1.2
1.22
1.57
1.57
1.58
1.67
1.67
1.68
1.96
1.96
2.2
2.24
2. 2


6.10
6.10
6.10
6.05
6.10
6.08
8.75
8.75
8.75
6.49
6.52
6.46
8.5
8.:7
8.76
6.93
7.00
7.01
7.82
7.80
10.10
10.10
10.10
7.82
8.72
8.71
8.71
10.75
10.80
10.80

11.62
11.61
11.60
12.59
12.63
12.65
15.50
13.30
15.31
13. 82
13.83
1 .81
14.70
14.66

11.49
11.42
12.98
13.00
1i.01
14.41
14.40
15.21
15.18
15.19
16.72
16.70
17.80
17.79
17.81


13.42
15.-4

13.3-
15.45
15.

13..4
15.41
13.
13.2

13. 1
15.3-

13.145

13. 4
15.3


15.45
13.26
13.27


135.45
15.27


13.45
15.4

18.69
18.73
18.7
18.78
18.73
18.71
18.78
18.71
18.74
18.76
18.73
18.75
18.71
18.66
18.75

22.22
22.48
22.36
22.30
22.5
22.47
22.50
22.42
22.4
22. 6
22.45
22.48
22.23
22.16


0.512
.500
.505
*559
.608
.610
.613
.612
.611
.636
.633
.656
.671
.669
.669
.716
.720
.727

.723
.723
.72514

.81
.724
:8-
.8534
.B I
.851
.829
.850
.629

.562
. 62


.6308
.611
.61138

.718
.714

.824
.822

.425
:412
4514

.502
.501
.504
.608
.608
.612
.718
.717
.817
.820
.818


2.58
2.38
2.02
2.02
1.92
1.91
1.91
1.87
1.8
1.88
1.62
1.65
1.63
1.52
1.2
1.:
i,
1. 1
1. 0
1.2

1.533
1.17
1.17
1.18
1.14
1.14

2.29
2.29
2.26
2.00
2 00
2.00
2.00
1.84
1.84
1.84
1. 1
1.51
1:52
1.19
1.19
1.19

5.19
3.37
2.95
2.95
5.00
2.50
2.50
2. 0
1.63
1.84
1.37
1.57
1.10
1.09
1.10


26.9
26.5
26.9
28.8
28.8
31.3
31.3
32.0
32.0
32.1
32.4
32.4
32.4
54.6
34.8
34.6
55.9
36 0
36.2
56.2

37.2
37.1

740 .
40.5
42.1
42.2
42.2


40.8
40.9
41.2

43.8
:.7
45.
45.6
45.7
50.5
50.2
50.2
56.8
56.7
56.9

41.1
40.5
*41
43.0
2.7
47.0
4.O
4.9


..0
63:
70.:
Z9:;


145.3
145.o
123.0
122.2
106.5
106.5
100.7
101.6
100.7
98:

.0
86.2
86.6
80.2
80.0
78.6
78.7
79.0
75.1
75.2
74.5
0.1
65.1
63.2
6o.1
59.9
59.9

62.2
61.9
61.0
5.8
54.1
54.2
49.1
49.
40.7

32.1
41.1
32*.
32.4


61.3
62.5
56.0
56.53
57.0
4.0
46.9
47.0


20,6
20.6
20.9
21.3


82.5
82.6
83.1
80.1
80.o
77.4
76:4
76:9
7Z.5


77.5
714.7
74.
72.6
72.2
72.5
72.5
72.:


69.6
65.6
65.2
64.1
63.7
65.2
65.2

61.5
61.8
61.6
57.8
57.6
51.7
56.0
56.1
56.3

55.7
51.2
51.5
51.8

62.9
65,6
5:7.
59.4


51:8
51.1
9.1
49.0
47.0
47.9
4.9


0.961
.95
.91
O9R
.975
.992
.945
.985
.95
.96
.998
.990
.992
:98
:99
.993



.966

.945
.973
.972
.978
.968




.972
.920
.922
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i950
.8
.780
.785
.780
.611
.625
.655

.985
.962
.950
.9;9

. 8

.685
.659
.686
.558
.5 o0

.457


-e = ---2a- where Ec = 10,500 ksi and 0 = 0.5.
'1 12(1-p2) qb.


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS


' "

















I 4N ac--- o0 OC- q aFm o i o M o0 -oOOC o\
u \0\C\\ONONO< OOC,6 c- ocr--,r-o L i



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NACA ARR No. L5FO8a


*

II


1t




0
0
0
0








0
Il







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H
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b
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INACA ARR No. L5FO8a


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o


gr
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a
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a1






NACA ARR No. L5FO8a


*--W

bw

I1
r /I


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS


Figure I.- Cross


sections


of H-, Z-, and


channel-


section columns.


Fig. 1






NACA ARR No. L5FO8a


ttw=0.5
Buckling of web
rps rained b vJ-lana\ge



NATIONAL ADVISORY
S\ \I COMMITTEE FOR AEONAUTIC



Bu of flan restraned db web
\ \ \ \I l t I i l ai l


i ^Ss\\O
EZ_^S1.2


Figure 2.- Values


of k/w f
of kw for


H- section


columns. (From reference 4.)
0cr,_ kwT Ec V
Tn 12(lI-) bw2


Fig. 2


J







NACA ARR No. L5FO8a


0 .4 .6 .6
bf/bw

Figure 3.- Values of kw for Z-and channel-
section columns. (From reference 4.)
Ocr kw T2E tw2
in i2z (0-) b"


Fig. 3







NACA ARR No. L5FO8a


Figure 4.- Local instability of an H-section column.


Fig. 4









NACA ARR No. L5FO8a Fig. 5












V 2 E
Cv I




















0







-P
E
oc
?I-


U,


x

L







--,
-\---- ^ ---- ^ -4-


#1)

4
-4-







NACA ARR No. L5FO8a


NATIONAL ADVISORY
COMMITTEE FOI AERONAUTICS


Fiqure 6. Variation of the compressive yield stress
over the cross section of an extruded H-section
of 755-T aluminum alloy. (Values in ksi.)


Fig. 6







NACA ARR No. L5FO8a Fig. 7





E _
0 c- I-

13





LL C
L- 4C






CD >

o0 -






SI C
eT E




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(N x -"0


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--- 5 + -







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-= <




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NACA ARR No. L5FO8a Fig. 8



0




0C
_______ 0





"< IL


0 0


.__ oo Q





SC,,
0 E
r4--
o ._.- C







to O



co
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oo r
0 ._ x






S-oi
0)


o a4
-9 c 1n o=
-- -- ---- .o4


F" ^i






N4ACA ARR No. L5FO8a


Oc r, ksi


20- o -


D L
NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS
0 20 40 60 80

bw z/120-p2)
_w p2)
tw V kw

Figure 9. Plate -buckling curve for extruded
755-T aluminum alloy obtained from
tests of H-, Z-, and channel-section
columns. cy = 79 ksi.


Fig. 9







NACA ARR No. L5FO8a


0 20 40 60 80 100 120 140
O-cr/n ,ksi
Figure O.- Variation of acr with ocr/n for plates of extruded
755-T aluminum alloy obtained from tests of H-, Z-, and
channel-section columns. Cac= 79ksi.


Fig. 10







NACA ARR No. L5FO8a


Ocr,ksi 41

L kor IL


20 -- -- o --- -- -



10 a LJ

o H
NATIONAL ADVISORY
0 COITNrTEE FM M MMWTICS
0 .2 .4 .6 .8 1.0
Ocr/"max

Figure II.-Variation of ocr with ocr/Fmax
for plates of extruded 75S-T aluminum
alloy obtained from te5t5 of H Z-, and
channel- section,, columns. ocq= 79 ksi.


Fig. 11








NACA ARR No. L5FO8a


mx,,ksi





o H


SLJ
oio


I


0 20 40 60 60 100 120 140
-cr//, ksi


Figure 12.- Variation of Omax with acr/' for plates of extruded 753-T
aluminum alloy obtained from tests of H-, Z-, and channel- section
columns. o cy =79 ksi.


Fig. 12




r





UNIVERSITY OF FLORIDA


3 122 08106 552 5



F L 32"- r F 03
1 *' .1u -", L "', ;. ";'

. .. 1177 11
,i.':ILL, FL 32-611-700 1USA













































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