Effect of variation in diameter and pitch of rivets on compressive strength of panels with z-section stiffeners

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Material Information

Title:
Effect of variation in diameter and pitch of rivets on compressive strength of panels with z-section stiffeners
Alternate Title:
NACA wartime reports
Physical Description:
1, 4 p. : ill. ; 28 cm.
Language:
English
Creator:
Dow, Norris F
Hickman, William A
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:
Rivets and riveting, Aircraft   ( lcsh )
Aerodynamics -- Research   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
Summary: An experimental investigation is being conducted to determine the effect of varying the rivet diameter and pitch on the compressive strength of 24S-T aluminum-alloy panels with longitudinal Z-section stiffeners. The panels were selected on the basis of available design charts, and the panel proportions were limited to the region of these charts in which the panels have the closest stiffener spacings and the smallest values of width-to-thickness ratio for the webs of the stiffeners and have such length that failure is by local buckling. The results showed that for these panels the compressive strengths increased appreciably with either an increase in the diameter of the rivets or a decrease in the pitch of the rivets. Data are also presented from which the rivet diameter and pitch required to develop a given stress in the panels may be determined.
Bibliography:
Includes bibliographic references (p. 6).
Statement of Responsibility:
by Norris F. Dow and William A. Hickman.
General Note:
"Report no. L-44."
General Note:
"Originally issued August 1945 as Restricted Bulletin L5G03."
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 - 003638639
oclc - 71843588
sobekcm - AA00006256_00001
System ID:
AA00006256:00001

Full Text
IVA-P


L -qL


NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS




WARI TIMEI RE PORT
ORIGINALLY ISSUED
August 1945 as
Restricted Bulletin L5G03

EFFECT OF VARIATION IN DIAMETER AND PITCH OF RIVETS
ON COMPRESSIVE STRENGTH OF PANELS
WITH Z-SECTION STIFTENERS
I PANELS WITH CLOSE STIF'lNER SPACING THAT FAIL
BY LOCAL BUCKLING
By Norris F. Dow and William A. Hickman

Langley Memorial Aeronautical Laboratory
Langley Field, Va.


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.


DOCUMENTS DEPARTMENT


L-44


RB No. L.GO0


/




































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/effectofvariatio001ang






NACA RB No. L505O3

NATIONAL ADVISORY COMMITTEE FO AERONAUTICS


5rESTRICTED BULLETIN


EFFECT 0? VArIATIIC: I:N DIAMETER A.D PITCH OF RIVETTS

Oil COMPRESSIVE STEIIGTT OF PANELS

iAITH Z--SECTION STIFFEFERS

I PANELS V;ITM CLOSE STIFFEI.ER SFACINIG THAT FAIL

BY LOCAL BUCI'KLING

By Norris F. Dow and William A. Hickmnan

SUMMARY

An experimental investigation is being conducted to
determine the effect of varying the rivet diameter and
pitch on the compressive strength of 2[S-T aluminum-alloy
panels with longitudinal Z-section stiffeners. The panels
were selected on che basis of available design charts,
and the panel proportions were limited to the region of
these charts in which the panels have the closest stiffener
spacings and the smallest values of width-to-thickness
ratio for the wees of the stiffeners and have such length
that.failure is by local buckling. The results showed
that for these rainels the comnpressive strengths increased
appreciably with either an increase in the diameter of
the rivets or a decrease in ,he pitch of the rivets. Data
are also presented from- which the rivec diameter and pitch
required to develop a given stress in the panels may be
determined.

INTRCDUC T ION

The design and analysis of sheet-stiffener panels for
aircraft structures have been the subject of extensive
experimental and theoretical inv-stigations, but the deter-
mination of the size and pitch of rivets for attaching
sheet to stiffeners is a problem that has not been ade-
quately solved. In reference 1 charts ind procedures are
presented for the design of Z-stiffened panels to carry
a given intensity of loading at a given panel length. The
test data on which these design charts were based, however,
were obtained for an arbitrary diameter and pitch of the








NACA RB No. L5G03


rivets. Because reference 2 indicates that the local-
buckling strength of panels having triangular stiffeners
at close spacings could be varied over a wide range by
varying the rivet diameter, an investigation is being con-
ducted in the Langley structures research laboratory of
the NACc to determine the effect of varying the rivet
diameter and pitch cn the strength of 24S-T aluminum-alloy
panels with longitudinal Z-section stiffeners of the type
for which the design charts of reference 1 were prepared.

Results are presented of the first series of tests
for the investigation. The tests of reference 1 were made
on approximately 700 panels and, since any number of com-
binations of rivet diameter and pitch is possible for each
panel, the results of the tests on the 1l40 panels reported
heein can cover only a very small region on the design
charts of reference 1. The region so far investigated is
the local-buckling region of panels having the closest
stiffener spacings and the smallest values of width-to-
thickness ratio for the webs of the stiffeners of the
panels given in reference 1. Panels of these proportions
were chosen to be the first investigated because the con-
nection of stiffeners to sheet is believed to be most
critical for such panels. Further testing will be required
to determine the effect of rivet size and pitch on longer
panels, particularly on panels of maximum structural effi-
ciency in which failure occurs as a combination of local
buckling and bending as a column.





L length of specimen

p radius of gyration

L/p slenderness ratio

iW width of specimen

bS spacing of stiffeners on sheet

bA width of attachment flange of stiffeners

bTy width of web of stiffeners


width of outstanding flange of stiffeners








IiACA RB No. L5G 055


tg thickness of sheet

tI t thickness of web of stiffene-s
d diameter of rivets

p pitch of rivets

h depth of countersink for rivets

Ocy corpressive yield stress for the material
of average cornoressive stress at failing load for any
specimen

Pi compressive load oper inch of parnl width

c coefficient of end-fixity in the Euler column
formula


TFST SPECIMENS AND ~ET.HOD OF TES.TITI,


The soecimens consisted of 243-T alumiinum-alloy panels
having Z-type stiffeners, a? shown in figure 1. The stiff-
eners on all panels were icentical. The sheet thickness
was varied to gi~'e five electedd ratios of stiffener
t...
thickness to sheet thickness: = 1.25, 1.00, 0.79, 0.65,
beo t b,- b .
and 0.51. The proportions = 5, = 2C, -- = 9.5, and
bF
--= 0. were chosen to give the panels of reference 1
b,/
that have the closest stiffener spac.ngs and the smallest
values of width-to-thickness ratio for the webs of the
stiffeners. The lengths of the panels w.,ere so chosen
= 20) that no column failures occurred. AccordinErly,
the term "comrressivP strength" as arclitd herein to the
panels of the present investigation is used to indicate
the strength of the panels for local buckling failures of
the general types shown in figure 2.

Tests were. made to determine the material properties
of the sheet used for the construction of the specimens.
The maximum with-grain conpr3ssive yield stress coy
obtained for the material used for the construction of the








IACA RB Io. L5G03


specimens was 46.0 ksi. The minimum value of ocy
obtained was 41.3 ksi. The average value of Ocy obtained
froa the results of tests of stress-strain specimens cut
from all the sheets of material used in the construction
of the panels was l0.7 ksi. The foregoing values of Ocy
represent the with-grain properties of the flat-sheet
material before forming.

The rivets used throughout the investigation were
A17S-T flat-head rivets (ANr4i.2AD). Both the size and
pitch of the rivets were- varied for each ratio of sheet
thickness to stiffener thickness as is shown in table 1.
The minimumr rivet oitch used in all cases was equal to
three tires the rivet diameter. On all panels the rivets
were driven by the FACi flush-riveting process in which
the rivet is inse-rbed with the head opposite the counter-
sunk end of the hole, the shank of the rivet is driven
into the--cavity formed-by t'-- countersink,-aind the excess-
material is removed with a milling tool. A countersink
angle of-600 was used throughout. The depths of counter--
sink used are given in table 1.

Ultimate comnressive. loads for the 1i0 specimens were
determined in a hydraulic testing machine having an_ accu--
racy of one-half of 1 .percent of -the load. The ends of
the specimens were-.ground .flat and parallel -before testing
to insure an even distribution of load over the panel.


RESULTS


Because the present- investigation covers -only the
local-buckling region of a small part of the design charts
of reference 1, no attempt-is made herein to present the
data by plotting the average stress at failing load of
Pi
against the parameter as in referenee1.. .Instead,
fo is plotted against_ the ratio of rivet diameter to the
d
sum of thicknesses of sheet and..stiffener in
tS+tW
figure 3 in order to present the results in a. manner- imi-
lar to that used. in reference 2. IThlnnerical values of af
Pi
and L/-, however, are listed in table 1. Figure 5 shows that,
L/vC
for all values of t-./tS investigated, the compressive
"strenrgths increased appreciably with either an increase
in the diameter of the rivets or a decrease..in the pitch
of the rivets.









iJACA RB ITo. L5GO~


Figure 3 indicates that no substantial increase
occurs in p-.nel strenl-,th for values of greater
to+tl
than approximately 1.5. Although the v ilue of 1.5 is
somewhat higher than the value of 1.25 obtained d in
reference 2 for triangular stiffeners w. ;h the particular
rivet pitches investigated therein, the carves of figure 5
show only small increases in panel stren,-h above values
d
of -- of 1.2r.
ts+t,,

The rivet pitch required to develop E given stress
in panels of the proportions used herein nsy be determined
from figure 5. For excaimopl:e, if it is desi-ad to develop
a stress eaual to the sverage yield stress 'f the material
(in this case I3.7 ksi) figure 5 indicates that at a rivet
diameter 1.5 tim the cver-all (sheet pli.s .tiffener)
thicikness a rive' pitch of less than 7/E'L in .i is required
for each of the -?ive vSalues of t.-7/tc iflnv st. ;ated.


CO'ICI UDITG REMARFSS


Results are orescnted of tests to determine the
effect of var--in- ri"-t diar.ter -r:nd rivet o tch on the
co'rpressivne ztreth of 2.S-T al.iinur--alloy panels with
Z-section stiffen-rs. The panels ,,er= selected on the
basis rf availal;:;e desi-n charts, and the panel proportions
were limited to the re-ion rf the.e charts in which the
panels have the clcsest stiffener spacings and the smallest
values of w'idth-to-thiknress ratio for the webs of the
stiffeners and have such length that failure occurs by
local buckling. The rcsultz sho'v.,ed that the compressive
strengths increased aop:rtcicnlar w-vth either an increase
in the diameter of the rivets or ; decrease in the pisch
of the rivets. Data are also presented from which the
rivet diameter and pitch required toc develop a given
stress in the panels may be deter-.mind.


Langley Memorial aeronautical Laboratory
IHational Advisory Co.'ini'ttee for Aeronautics
Langley Field, Va.








6 NACA RB No. L5G03




. Schuette, Evan H.: Charts for the 'i ii.-'.VeiSht
Design of 24S-T Aluinirum-Alloy Flat Compression
Panels with Longitudinal Z-Section Stiffeners.
NACA ARR iTo. L5F15, 1945.

2. Dow, Norris F., and Hickman, "'illiem A.: Prellninary
Investigation of the Relation of the Compressive
Strength of Sheet-Stiffener Panels to the Diameter
of Rivet Used for Attaching Stiffeners to Sheet.
NACA RB No. L-1, 19 4.






NACA RB No. L5G03


TAMEE 1.- NOMINAL DIMENSIONS OF Z-STIFFENED PANELS AND TEST RESULTS
SHOWING EFFECTS OF VARYING RIVET PITCH AND RIVET DIAMETER

tS 0.051 in.; bS = 1.28 in.; L = 10.50 in.; W = 7.02 in.;
tW bs bw
.= 1.25; = 25; -- 20
tS 'tS /w

Diam. of Depth of Pitch of Average stress Pi
rivets, countersink, rivets, at failing load, /
d h p af
(in.) (in.) (In.) (ksi) (ksl)


1/16






3/32





1/8






5/32








A16





1/14


0.035






.040
.oho





.050






.060







.060






.060


"Average of two tests.


3/16
3/8
5/8
1516


91



15/16

It

3/8
5/8
15/16




156
5/8
15/16

156

16






3


15/16
151



16


15/16
'i6


44.0oo
a43.750
a37.350
34B.500
a30.350
a30.175

& h..6oo
a. 8600
a14.825
a41.900
37.650
5-.900
832.1470

44.840
59.100
39.400
36.100

a35.575

,4.950
45.100
10.750
a37.425

36.125

45.900
45.o00
42.150
a37.850

a36.615

435.o000
42.750
59.o00

36.600


1.304
1.093
1.014

.902

.895

1.329
1.357
1.217
1.119
1.o04
.961

1.551
1.278
1.173
1.078
1.069

1.551
1.308
1.208
1.120

1.086

1.418
1.512
1.255
1.132

1.105

1.200
1.280
1.178

1.080


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICSCS






NACA RB No. L5G03


TABLE 1.- NOMINAL DIMENSIONS OF Z-STIFFENED PANELS AND TEST RESULTS
SHOWING EFFECTS OF VARYING RIVET PITCH AND RIVET DIAMETER- Continued

tS = 0.064 in.; bS = 1.60 in.; L = 10.40 in.; W = 8.64 in.;
tW bs bw
t- 1.oo; = 25; = 20
Diam. of Depth of Pitch of Average stress f -
rivets, countersink, rivets, at failing load,
d h p f(ks)
(in.) (in.) (in.) (ksi) (ksi),


1/16







3/32





1/8






5/32





3/16






1/4


0.035






.040






.050





.060





.065






.065


aAverage of two tests.


3/16
3/8
5/8
15/16
1j

L


9/2
3/8
15/16
1i

12

3/8
5/8
15/16



1-1
1
4
15 2
5/
15/16
5
16


9/16
5/8


1


15/16
I i


4.o050
4- .50
a36 .855
a38.350
29.300
26.700





33.400
30.700

44.600
a43.735
a41.710
54.750
32.200

45.000
45.870
40.500
36.100

a33.800

5.340
.700
40.850
37.600
a33.800

44.485
44.485
38.900
35.350


1.233
1.180
1.015
1.095
.840

.76.8

1.303
1.245
1.069
1.140
.950
.891

1.317
1.227
1.186
.990
.856

1.318
1.197
1.142
1.052

.973

1.329
1.232
1.160
1.077
.968

1.272
1.290
1.104
1.022


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS






NACA RB No. L5G03


TABLE 1.- NOMINAI DIMENSIONS OP Z-STIFFENED PANELS AND TEST RESULTS
SHOWING EFFECTS OP VARYING RIVET PITCH AND RIVET DIAMETER- Continued

tg = 0.081 in.; bs = 2.03 In.; L = 10.06 in.; W = 10.77 in.l
tvr bS -b
= 0.79; s = 25; r- 20

Diam. of Depth of Pitch of Average stress Pi
rivets, countersink, rivets, at failing load, V
d h p Of
(In.) (In.) (In.) (ksi) (ksi)


5/52







1/8







5/32






5/16






1/4


0.040







.o060o


.065






.075


.080


9/52
9 6
7
1
32
12
2


3/8
9/16
7/8
1--
32
112
32
2

15/52
9/16
7/8
1-L
32
52
lid
32

9/16


112
32
32
2


7
17
112
32
2


___________________ J _____________________ 1' i.
two tests. NATIONAL AnVISORY


42.500
41.500
3?7.550
a56.935

32.900
27.610

45.700
42.800
539.420
37.550

34.820
29.550
a43.900
453,600
40.655
58.800

54.750
30.800

45.650
40.845
40.100
35.900
a51.280

44.200
a2.750
841.450
57.200
33.000


1.2b7
1.209
1.07h
1.082

.964
.807
1.286
1.253
1.1o0
1.090

1.015
.858
1.275
1.266
1.161
1.151

1.018
.892

1.528
1.175
1.167

1.056
.915
1.527
1.228
1.217

1.089
.964


aAverage of


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS


two tests.






NACA RB No. L5G03


TABLE 1.- NOMINAL DIMENSIONS OF Z-STIFFENED PANELS AND TEST RESULTS
SHOWING EFFECTS OF VARYING RIVET PITCH AND RIVET DIAMETER Continued

ts = 0.102 in.; bS = 2.55 in.; L = 9.44 in.; W = 15.39 in.;
tw bs bw
S= 0.63: = 25; = 20
tS "S -W
Diam. of Depth of Pitch of Average.stress Pi
rivets, countersink, rivets, at failing load, L/VE
d h p f(
(in.) (In.) (in.) (ksi) (ksi)


3/52







1/8







5/52






3/16


aAverage of
bAverage of


0.050







.o6o
.060







.070






.080






.090


9/32
9/16
7/8


1 2
2

3/8
9/16
7/8
1-
52
12
32
2

15/32
7/8
52
19
32
2

9/16
7/8
17
15
32
112
32






2
2


42.500
59.500
38.170
35.400

54.500
30.000

45.800
40.400
39.700
57.800

55.500
50.2240
a43.590
a42.335
41.050
57.850

55.750
51.800
a45.150
b41.150
58.800

58.150
51.900
44.050
a43.ooo
40.700

59.800
54.100


1.412
1.288
1.218'
1.158

1.129
.984

1.445
1.321
1.263
1.237

1.167
.984
1.451
1.388
1.510
1.256

1.168
1.049
1.451
1.327
1.265

1.253
1.042
1.471
1.378
1.529
1.507
1.120


two tests.
three tests.


NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS







NACA RB No. L5G03


TABLE 1.- NOMINAL DIMENSIONS OF Z-STIFFENED PANELS AND TEST RESULTS
SHOWING EFFECTS OF VARYING RIVET PTTCH AND RIVET DIAMETER-Ccncluded
tS = 0.125 in.; bS = 3.15 in.; L = 8.70 in.; W = 16.27 in.;
tw bs bw
S0.51 t; 25; i = 20
tS ts W

Diam. of Depth of Pitch of Average stress Pi
rivets, countersink, rivets, at falling load, 7c
d h p af
(in.) (In.) (in.) (ksil (ksi)


1/8







5/32






3/16






1/4


0.070







.080






.090






.100


3/8
9/16
7/8

32
112
32
2

15/32
9/16
7/8


112
32
2

9/16
7/8
7
13
32
112
52
2

34
7
l-L
132

2


42.000
41.200
39.190
38.050

a37.425

33.600
41.600
l1.550
40.150
a38.805

36.200
14.500
142.700
41.180
39.450
57.500
34.900
a42.600
42.200
1i.o00
38.560
a37.150


1.595
1.563
1.L67
1.h-o
1.409

1.260

1.595
1.558
1.489
1.175
1.360
1.296

1.685
1.488


1.313
1.60Q
1.58U
1.566
1.452
1.396


aAverage of two tests.
NATIONAL ADVISORY
COMMITTEE FOR AERONAUTICS






NACA RB No. L5G03


Fig. 1








NACA RB No. L5G03 Fig. 2


...'... ..: .































e
C1
2.Q* e
cD

L4
















__
b;
t .',_ .. -


Im '.













i I~III-I ,', .' ,/ r






NACA RB No. L5G03


.4 /.2 /.6 2.0


Figure 3. .-Var/ation


d
ts* tw

in local buckh/ng strength of pane/s
with rivet d/armeter.


Fig. 3


6o







NACA RE No. L5G03








40
t-= 0.5/
I T
( = o. /s)
30









40
.63


(IOZ)
JO









40
.779



Jo I


Fig. 3 Cone.


d
tFigure Concded.
Figure J Concluded.


















































































*L







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