,.-1

b

,-.

4

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.

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t

NATIONALADVISORY‘COMMITTEE ~FORAERONAUTICS

.

TECHNICALNOTE

No.1177

EFFECT OF RP@T OR BOLTHOLESONTHE ULTIMATESTRENGTH

DEVELOPEDBY 243-T ANDALCLAD 75S-T SHEET

IN INCOMPLETEDIAGONALTENSION

By L. Ross LevinandDavidH. Nelson

LangleyMemorialAeronauticalLaboratoryLangleyField, Virginia

.-

WashingtonJanuary1947

--

——

——

https://ntrs.nasa.gov/search.jsp?R=19930081942 2018-10-29T14:00:10+00:00Z

NATIONALAIKEORYCOMMITTEE— ———

TWJiNIc-!!.WTE No.—..—

FORAERONAUTICS

IJ.77.

EFEWT OFRIKPlCRBOLTHOLESONTHEULTIMATEStiTGTH

DEVEL02EDBY 24EWPMTDALCIAD75S-TS-

IN INC~RIE DIJXW.ALTENXEOR .-

3y L.ROESI.evinanclDavidH. Nelson

mMMARY

Stren&thtestsweremadeof a numberof2kS-TandAlclad753-T~~nm-~~oy s~~~ web~to dete~~~ theeffectofrivetorbdthole&ontheshesrst~erqtih.Datawereobtaine&fm webswhichapproacheda conditionofpureshearst~+essaswel.iasforwe%swtithwell-develqeddi~aml tension.Tl??rtVOtfactor,(pitchminusdimeter)di-rl.dedby pitch,wasvsrledL=omapproximatelyo,& to 0.62.Thesetestetrticatedthatthesheszstressesouthegrosssectionwei>ene=-ly~onatantTorallvaluesoftherivetfactorinvesti[:atedi:.tfieother~o~ertiesofthewebwere .—.—notcheqed.

IRZRO~CTIOl?

Thestren@hofa sheezwebis sometimes’caayztedw the .... ,_L_asswptionthatfailzz-ewSlltekeplacewhentheshearstressonthenetsectimnbetweenrivetorbaitholesreachestheultimateshGarstl’essof’themateriel.Tlis.~acticeisanalmgousto the

—.

methodusedforccqm-tiRGtkestrea@hoftermionmemberstithholes,exceptthatmenyofthelight@.10YEl@ ~~ ~c?aft s!ruc~~e~ _.aroknownto showstress-concentrationeffects01holesatultimate -.loed. Theseeffectsmustbe takeninto=CountWhencmputi%thes5ren@hoftensionmembers.Smilerstress-concentration

.—

effectsmaybe erkectedin @ear wf3Ds..—

Anothar.~fficultyinvolvedincoqmtingthestzen@hof shew welmisthatnorec2.Qsat.is-““factorymethodof Leteiminizzqtheul.timate she= stressOfa _.thinsheethas%eendevised.

Becauseofthesedifficultiesthemostexpedientmethodofdetex?niningtheellowablestressforshearwebswithrivetorboltholesisby directtestson shearwelsfastenedwithrivetsorboltsendsubjectedtopureshearload.,whiletheratioofpitchto diameterisvariedto evaluatetheccaibinedeffectofreductioninsectionandstressconcentrationercmndholes.Thestiffeningofthewebsshouldelsobe varhd Inordertodeterminetheeffectofchengingfromthenearlysheer-resistantweb(failureoocurssoonafterbucklingtekesplace)tothepartlydiagonel-tensionweb(failureaccurslongaftQ2 buckllngtakespleoe).Theresultsof suchtestsmadeon2&-T andAlclad75S-Taluml.num-al.loysheetsoregivenherein.

%7

L

P

d

P

t

%llt

‘Jperf

T

Tg

Tn

‘ga~

Tat

SYMBOLS

( -d netareaS3W lineofhol-rivetfeztor—

\pP 0’grossareaa30nglineofholes)

lengthslcngonesideof shearpeaelbetweencornerlolts,inches

loadrequiredto failysnel,klps

diemeterofrivetorboltholes,inches

pitchofrivetorboltholesinoneraw,Inches

thicknessofsheet,inches

ulthatetensilestress,ksi

ultimatetensilestressannetsectionofperforatedtensilospecimen}ksi

sheerstressonweb,ksi

sheerstressongrosssectionofweb,ksi

shmr stressonnetsectionofwelbetweenrivetholes,ksi

averagemeasuredgrosssheeretressatfailurefarmetypeofspecimen,ksi

ultimatesheerstressofmateriel,ksi

.

L

-

.

b

—.. .,—.- ..— ..— —-———-

3

-—.—

- —.-—

— —... —.. —

In alltestmthepitchoftheholeswas1 inchandtheholeM.smoters,usedto obtaina vsrts.tioninpitch-tc-tianwterre.tiojwere3/16, 1/4, 5/16, end3/8 inch.

Thete~tepeclmermwerecutfrc.m&evoral.di.fferontsheets0:matez-ial.Ultimatetensilestror@hsof Gachsheetofmaterialworedetermined,frcmthefollow5~woups ofcontrolspecimens:

.—

(a) mmthe grain

(1)) Twotc thegrain

(c) Two

stsnderdtensilospecimenscutperpendicular

~erforatedtensilespcimenscutpand.leltothe~aln foreachsizeGfholeusedintheskEarw@E(eightspecl.mons)

(d.)Tvoperforatedtmnsilespecimenscutwrpendic.ulertothograinforeachsizeofholeusedinthesheszzwebs(ei@tspecWns)

ITACA~ No.~774

Theperforatedtensilespocbonsuentionedunder(c)end(d)weredmipawitha widtheq~wd.to thepitchoftheholceintheshea~websandwttha holeInthemiddleofeachcorrespomlh~to oneoftheeizeewed intheshearwebs. Theseperforatctispecimenewereusedto eve2ua.tetheetvesti-coneonti”alxioneffectaatultimateloadundersim~letensionlIo@.

TlI$32.XRSUIITS‘

Theslhca.rstressatfailurew comybtedforbth thegroe~sectionandthonetRoctiona2.IOWtIi~ltnjd’holesandreducedtotheminimumguaranteedpropezztiesoft~omaterial.Theshearstressatfailureonthe&oss nec~ionof:eachspectintestedIinthe~.ectan@l.arfremewe.Hccmp-whedby

pT,-==&”” (1)-- ,,1,

Forthe

Thehole~wascomputedf~i-eachspecimenby ;

.-cutperpendlml.arrofwcncc1 wtates —.

5

thata 6pecimencutfromthesheetinEJqVdirectionshallpossessthecertainminimum~yxcranteedproperties.giveninth@ referenceTaper.I’orthestsnderdcross-~ainspeafmensj

.=u~t wasgenerally

from2.2to s.4 percentlessthanioiifihestsrkkmdwith-~ainepoctiens.(Seetable1.)

ThereducedV&l-U9sof T~ and Tn areshowninfigures4 end5fromwhich,a~erently,

—Tg. isnearlyconstantwhile Tn-decreases

SS Cr increases.l?i~vre~4 aid5 showtheaveuagevaluesof “.grossshearstressatfailu??eTeav foiathewebswithedgesclmped

letweena hea~ plateaudstiff”wo.shersorTetweentyohea~ plates.Thevslusof’T ~av was 36.9 hi for the st Liiened Alclad.7%-T websy

31.9ksifortheunstfffenedAJclad75S-Twebs,30.3ksiforthestiffened24-S-Twebs,end25.8ksiforthemmtiffened24s-Twebs.Theindividualvaluesof T~ inanygroupdidnotvarymorethen9 Fercentfromthesevaluesof T~a~ andmostoftheIMUMIRf@.l_ ...... .:==,

within5 ~rcentoftheaverase.Figure5 showsthesevariationsbetweenT~av S3YdlndiVi&,ldVdJ’.e3Of T fol~thewebs~th

$ .ewes clam~edbetweena hea~~plateandstiffwashers.

~~~le1 @~e~fj]ie~.ltim~~e ~tre~s~sforthengtSectjj-onoftheperforatedtermile~ecimensaswellas fox+thestandard “”tensilespecimens.Thistableeko givestheatyggs-concentratbn ......._factcm atit/’agjel*fforthe~erforateds.peclmens,where a~t istheaverageultimatesti-essof twostandardtensilespecimensand‘~erf istheultimatetensilesbressontheEStsectionofaperforatedspecimencutinthescmedirectionasthestandardspeci- -mens. Inspectionoftable1 indicatesa sli@ttendencyfor ~perfto decreaseas ~ increases.

DISCUSSIONOFTES3TKEXJLTS

In aircraftstructurestheshearstressT~ onthegross .—-sectionofa shearwebis scmetiznescomputedby-fm’mul.a(1),andthsshearstressTn on”thenetsectionslq therivetorboltline,l)ydividing‘~ by Cr asindicatedby formula(~).Failureisaeknzmedto occurina strai~htUne alongtheCenterlineof’theholeswhen ~n becomesequaltotheallow-ablesheerstres~

.-

ofthematerial.Thissllowabledxessis sBsumedtobe inde~endentof chemgesinthepitch-to-dieneterratiooftheholes.Thepresenttests,however,seemto indicatethatthi~methodis not

correct.Thesotestsshowthatfailuretendstobe ina zigzaglinebetweenholesratherthanina straightline.Thetestsalsoindicat~thatthesheerstresseeonthenetsectionTnatfailurewerenotconstantasusuailyasmmwdbutdecreasedas Cr increased.

~SZ7idiOnS in cheer6tr~SSatf&ihlPQ.---,——. —.-.. I?iawoa4 and5andtable1 indicatethtitthedecreamIn Tn atfailureas Cr increasedwasler~eccznparedwiththedecreasein

‘porf ontheten~ilespecimens.Cwqy@tionsshowedthatforshearwebswith Cr approximatelyequaltoO.~~ Tn atfailurowasfrcm20to SOpercentleesthwnfortheshearwebsti.thCr ayym.ximatelyequalto O.6?, Tnble1 indicatesthattheEJtrem-concentra&lonfactcm crult/ayerfva:ed fmm 1.0~8to~1.088fortheAlclad”75S-~ elmuinmnalloysndfrcm1.044to1.202for24S-Taluminumelloyas Cl.variedfrom0.828to0.@6. Thesefactu,then,ind3catethatthev%wiationin Tncsnbe partlyeccountcdforby thestress-concentrutionoffuctsnotedinthotensiontests.

fk”ms shearstresso~at failure.-...—.__— F,iguzzGs4 and!3showthatT isa.hmstconstcmto~r ther-e of:Cr f%cmaboutO.&.t~ about0.62.Thoaver.zgcvaluesofgrbssshoewdrostiat‘&ilWe T~av c.re@von for&hecrwcbawith.theedgesclmqmd

for thoran.&of Cl.valuoacoverodinthGy’cscnttests.AsCr centinuosto decroaso,Tn will-bGccm.enearlyconstanti)cca.ueoit ie apyroachi.~a maximwnvsluosomowh@lossthan Ttit forthematerial;whenthisvil.ueisreached,‘ti%111nolo~er bo constant

butwilldocrcasoataboutthossmorate”as Crareaalongthelineofbolostowoss arpaalongdccroaecm.

, F

(:116ratioofnetth~linoofholes)

nu

that

COI?C!IZJSIOES,

Strengthtcutsweuemadeof shearwebsof 240-TandAlclad75S-Taluminl.mallo;:to determinetheeffectOfrivetor%~ltholescmtheslbwableCI:CSJ?etrcEsofthesematei%tals.In oi-dertoob‘,alndataon speclinensthatfailed.at cliffereiitSt+,%sofinccmgletc

b

-.

. .

—

1.The~hem stressesonthe#a-OEJSgactiionat.fail.ui-owGrealmostconstantforallve~uesof Cr il~ve~tlcatedt:theuthcrproperti.eaof hhowebwerenotchwged. ~ .—

2.Forwebswtththeed~osclsmpcdljetweentwohxi.-ryplat~sI

endstiffwashere,the.averaSeshearstruescnthu~c~s section. —

atfailurowas36.?ks!iforthestlffenodAlclad75S-Twebs,31.9ksi”forkhourwtiffcnedA1.clad‘7’X-Twebu,30.3keiforthefitll’fened24S-Twebs,and;~5.8ksifortheunstifi’aeddj}~-qwebs.

.-

~-* Xhenthewebswere~amtenedwitha heavyplateslow onesidewiththeLeadsoftheriveta oi}boltslem.-~directlyonthest..eetontheoppositeside,theshc~=~ti)engtihofthewebewasabout11 percentlossthanwhenthee@es werewellsuppol~edonlothsides.

LangleyI!emaialAeronauticalLaboratoi*y —

NationelAdvisoryComnitteeforAeronauticsLan@eyField,Va., September18,1946

-.

1. Anon. : FederalSFectfica:tonforAluminum-All.q(AL-24),(Aluminum-CopFer-Ma@esium(1.5 Fercent)-M~enese);Plates,Sleets,~.dStrips.Federal.StanLard-StockCatslog,Sec.IV,(Pt.5)QQ-A-355a,NOV.28,1941.

2“.Aeon.: fmcqv-l~a~AeronauticalSpecification>AluminumAlloy,Clad(AL-XB75C2);SheetandStrip.AN-A-10a,Dec.14,1943.

3. KuAn,Paul: llltimateStressesDevelo@ hy 2!S-Z!SheetInIncompleteDiagonalTension.NACATN No.833,19!1.

1}. Anon. : Stren@hofAircrafLElements.ANC-5,fi~-Navy-CivilCczmitteecnAircra?tlksi~ Criterta.Reviseded.~ Dec.1942;Amendment1, Oct..22,1945.

10 NACA TN No. 1177

TABLEI

TmsIIEsTREmz5 aFcoN!csoLSEEcmmsmminal Netarea up- %iLt m’ninal Neterea Uperf%iLt

Speoimendlemeter6roe0erea8(ksi)r *E@cimend.temeter(in.)

Grosserea’(kst)G*% (In.) q

24S4’ sheet1 I

Withgrain(u~~ = 71.62) --1---1.202 25

1.13.O 26 11.1591.I.321.1481.3.621.1551.1451J361.089I0.803 60.4

.798●748 E::.752 60.3.679.676 E::.606.613 E:;T3/16 o.812

3/16 .7921/4 .7531/4 .7505/16 .6825/16 .6723/8 ●@3/8 .632

59.664.563.264.364.763.864.764.8

3/163/161/41/45/165/163/83/811.I.33

1.131.1.101S221.I.O1.104

272829

%32

24S-T Sheet2 I(u&-@n*&)

I1.X281.124 :81.072 351.0721.030 %1.0791.056 %1.044 40

E:;63.463.965.964.565.16&2

3~63/161/41/45/165/163/83/8 I0.800 63.7

.a3 63.9

.751 6’7,0

.752 67.o

.683 66.5

.691 g.:

.625

.624 68:8 4l.1.zl.1.1031.0971.0881.0551.078L.0691.05.1

3/163/161/41/45/165/163/83/8

o.&)2.794●744.745

:%.626.621

910Ii121314

i:..

Alclad75s-Tsheet

I74.81.088 g 3/1678.21.039 3/1678.31.038 43 1/475.01.083 g 1/477.11.0% 5/1677.41.051 46 5/1677.31.052 47 3/876.31.064 48 3/8 I0.807 75.3

.802 74.3

.752 73.2

.744 74*7..682 75.2.690 73.8.620.&4 %

3/163/161/41/45/165/163/83/8

0.828.798●739.767.682

:%.61.8

1.0431.068

,

J

1.0731.0521.0451.0641.0411.052

NATIONALADVISORYCOMMITTEEFORAERONAUTICS

.-,

.

stiffeners on bothsidesof sheet 7

-lHlilffffff-wl-32 spaces each Ii %

534 I---i

I A= J Imu n .u n u mu .u .u n . l-l. n

unu “ .u n .. u u u

Figure .

NATIONAl ADVISORYCONt41TlEEm AERWUTICS

Stiffend shear web. Shed thtckmss, Q040 inch .

—

g.

I

Fig. 2

II H

~11 *Section A-A

TWOrows of holes.pitch, I

51*

d

‘%

A–

,2X$ aboth

A

Figure 2.- Rectangular frame ,

.

—

NATIONALADVISORYCOMMITTEEFORAERONAUTICS

NACA TN No.1177 Fig.3

7Filler used when sheetoutside of onales

J

isonn

-—- I T “—-.+

+ ‘1 ‘-e-e-~-e-e- . I

In

4-+

A 3

.

/22&x x steel cmqles4 ,Filler used here

when sheetIS betweenangles

1 I

Section A-A‘Filler

NATIONALADVISORYCOMMITTEEFa AERONAUTICS

Figure 3,- Squcyre frame .

16

.54 Ell

Oa

!31 36.9— .1 ~:— -k’ I

o Tg

o -fn

ld2i-dfcote rmkerof rows of txllt5

❑ !

aft 13e

., .,.. .,, . .,

1

CJ2

* 1- ,.I I

.6 .7 .8 iG~ .+ .; A

O)Stiffened skecr webs. u UrbSHfferd Sh?or webs; _-m—_

Fkpre 4.-Utinote M stresmg m M 755T webs. All sh.ses rwked to m“tirrun prunk+xlpqIErt@. web thickness, 0.040 Ml .

:1

l“,, .,!

1.-. . -

~l,l!” 1. I.;,, , ~.- , ,, ,, .—

.

r. .-.I

52t

‘Eli

32l--

o‘9

❑ Tn

>b No washers under headsof bolts

I ad 2 imlkmte number ofrows of bolts

s Inckotestests In sqme frmw

,.

24 .!I I I I I I

L .6 .7 0 .9 ‘b*,cr 7 A .; .

tIISltffemd sheer webs, H Lhwtlf fend .4wm webs. ~~m~~

Fkpw 5.- Ulllmate 4VZIr stres~ CTI 24.5-T web. All stresses timed to mirinwm ymrrked

pwperties. Web tMne-s5 ,0.040 inch,.

1’ I.,

1,,.

1

.

5- 0

8:0 8 c-l

0;5 0 .G -5- I I I I I I I 1 I I i I.-:g (a) 5tif fened 75.S-T webs. ~ Unstiffened 755-T webs .

4-

t

.4, .6 .8 1.0 .4 .6 .8 1.0d-ch

P{cW Cr. $

~(2 Stiffened 245-T webs. (d) Unstiffened 245-T webs .,

Fiqure 6.- Variations of indtvkkml 91-05sshear stresses from averaqe measuredgross shear Mress for shear webs with edqes supported on both sides.

tMTIONM A5VKWIY~mlhmawTKa

.