Torque Tension Loss

(LR-25049) TORQUE-TEISION RELATIONSHIPS AND-2, : STATIC PRELOAD LOSS OF HIGH STRENGTH, t l i i A i ! :.

RESISTANT , AND CORROSION RESISTANT AIHCP AET !' ''

ALLOY FASTENERS (Lockheed-California Co.) .,

TITLE

REPORT NO. Lfi L3ur7

DATE 12-23-71

MODEL

COPY NO. .i, TORQUE -TENSION RELATIONSHIPS STATIC PRELOAD LOSS OF HIGH ST HEAT RESISTANT, AND CORROSION RESISTANT AIRCRAFT ALLOY FAST

L O C K H E E D * C A L P F O I W N I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

IIEVISIOI\IS

I. ABSTRACT

This r epor t was prepared by the P a r t s and Equipment Department under

an Independent Development P r o g r a m . It descr ibes torque-tension and static

preload. l o s s tes t s conducted on high strength, heat res i s tan t , and cor ros ion

res i s tan t fas teners that a r e cur rent ly used o r intended for future use in

Lockheed-California Company a i rc raf t . All testing was conducted by Almay

Resea rch and Testing Corporation. All fas tener hardware was supplied by

Lockheed. The r e su l t s of this repor t m a y be used to determine the installation

torque requi rements for optimum joint preload.

The tes t data resulting f r o m this p rogram was generated by wrenching

the nut and was l imited to two installation cycles . The effect of two different

added lubricants was determined. These lubricants were MIL-T-5544, a

graphite base lubricant, and MIL-L-23398 (LAC -C34-1209A), a d r y f i lm

The conclusions of this r epor t a r e that the installation torque requi rements

of f a s t ene r s vary due to fastener ma te r i a l s , lubricants used, ra ted s t rength

of the f a s t e ~ e r , f inishes, and installation cycle number. In addition, each

installed fastener i s subject to a l o s s of preload during the f i r s t 7 2 hours af ter

installation; this l o s s m a y be a s much a s 11 percent of the init ial preload.

FORM 4020

L O C K H E E D * C A L I F O W M I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS REPORT NO.

PAGE NO.

11. ACKNOWLEDGEMENTS

The au thors w i sh to acknowledge the valuable a s s i s t a n c e prov ided dur ing

the c o u r s e of th i s p r o g r a m by the following f a s t ene r companies : E l a s t i c Stopnut

Division of A m e r a c e E s n a Corporat ion, Kaynar Manufacturing Co . , I n c . ,

O m a r k Indus t r i es P r e c i s i o n Fas ten ing Subsidiary , P. B. F a s t e n e r s Division of

P a u l R . B r i l e s , Inc. , Standard P r e s s e d Steel Co. , Valley Todeco, Inc. , Sub-

s i d i a ry of The Larnson Sess ions Co. and Voi-Shan, a division of VSI Corporat ion

T h e au thors fu ther acknowledge the contribution of Almay R e s e a r c h and

Tes t ing Corpora t ion i n pe r fo rmance of the tes t ing, which w a s accompl i shed

SECTION PAGE

ABSTRACT

ACKNOWLEDGEMENTS

TABLE O F CONTENTS

LIST O F TABLES

INTRODUCTION

OBJECTIVE

CONC LUSIONS/RECOMMENDATIONS

ii

iii

PARTS TESTED

TEST SPECIMENS

TEST PROCEDURE

DISCUSSION O F TEST RESULTS

APPENDIX

LIST O F REFERENCES

BIBLIOGRAPHY

IDC, , PE70/522 , J. B. Bie rbower to G,. V?. Davis , Dated 7-28-70, Subject: Torque-Tens ion Relationship - Engine To Py lon Attach Bol t s

DISTRIBUTIGN LIST

FORM 4020

L O G R H E E D C d L I F O I W M I I A C O M P A E Q Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVlSlONS

TABLE

IV. L I S T O F T A B U S

TITLE

TORQUE-TENSION TEST SPECIMEN COMBINATIONS

PAGE

I1 PRELOAD- LOSS TEST SPECIMEN COMBINATIONS I

L O C K H E E D * CALlIleORlPaBlIA C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REPORT NO. LR 49

I Shear, tension, and fatigue cri t ical bolts and nuts require different

1 installation torque l imits in order Lo achieve optimum joint preload. Fatigue-

sensitive, highly loaded joints a r e subject to premature failure of the s tructure

or fastener i f the fastener installation torque i s below optimum. An installation

torque greater than optimum can cause premature fastener failure by inducing

preloads greater than the fastener yield strength. Torque -tension relationships

for alloy steel , cadmium plated bolts and steel, cadmium plated, dry film -1. ' P

lubricated nuts a r e well documented (1). These established relationships a r e

available to designers via various reference manuals. The f i rs t objective of

this test program was to establish torque-tension relationships for fasteners

of mater ia ls other than those already documented. It had been suggested that

fastener preload attained from torque is subject to a loss with time. This loss

may be a result of relaxation in the joint or room temperature creep in the

fastener . This phenomena has not been investigated to any great degree by

pr ior investigators. The second objective of this program was to determine

the magnitude of preload loss a s a function of t ime for fasteners that a r e

currently in use.

After this test program was initially defined a recent torque-tension test

report ( 2 ) prepared by Almay Research and Testing Corporation under a NASA

contract was made available to us. After review of this test report our proposed

program was revised to eliminate duplication. The two programs now comple-

ment each other.

'::Numbers in parenthesis r e f e r to references listed in the Appendix,

FORM 4OZD

B O C K H E E D ~ A L I F O R M I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS REPORT NO.

PAGE NO.

V. INTRODUCTION (C ontinued)

Almay Research and Testing Corporat ion was selected to conduct

the testing f o r this program. Almay was chosen because: 1, they had just

completed the torque -tension study for NASA (which resul ted in a r epor t

of over 700 pages, see Ref 2), 2. they were located in the Los Angeles

a r e a s o testing could be monitored and coordination could be conducted

easi ly , and 3. their es t imate of cost was in line with budget predictions.

Testing was conducted under the supervision of Mr. H a r r y S. Brenner ,

Director of Research. Mr. Brenner offered to provide a wri t ten r epor t ,

besides the tes t data requi red by contract a t no additional charge. It was

fe l t that this repor t , which includes observations, photos, description

of t e s t equipment, and comments , would add greatly to the value of this

program. F o r this reason Mr. B r e n n e r l s offer was accepted. His

r epor t ( 3 ) h a s been submitted to the Lockheed-C alifornia C ompany l ib ra ry

OBJECTIVE

The f i r s t objective of this program was to provide torque-tension data

for bolts and nuts f rom which installation torque requirements could be

determined.

The second objective of this program was to determine the magnitude

of any static preload loss , a s a function of t ime, so that i t s significance could

be established.

FORM 4320

L O C K H E E D * C A L l F O R N l A C O M P A N Y 14 D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS

VII. CONCLUSIONS/RECOMMENDATIONS

The t es t r e su l t s will provide a i r c ra f t design engineers with accura te

torque--tension relationships f r o m which fas tener optimum installation torque

l imi ts (can be determined.

The data generated by this t e s t p rogram m a y resu l t in: (1) longer

lived, m o r e reliable a i rc raf t , ( 2 ) industry standardization of installation

torque l imits and methods, and ( 3 ) extending the life of the fas tener wrenching

sur faces .

It i s recommended that fur ther torque-tension t e s t s be conducted on

high strength, heat res i s tan t , cor ros ion res i s tan t f a s t ene r s . The object of

these t e s t s would be to determine the influence on joint preload due to:

( 1 ) Fas tener yield to ultimate rat io caused by flush, hex, and

12-point bolt head configurations,

(2 ) Wrenching the bolt versus wrenching the nut,

(3 ) Nut configuration (thin wall, thick wall, and plate nut types),

(4) Nonlocking ve r sus self-locking nuts,

( 5 ) Varying the thread pitch f rom fine to c o a r s e (in preparat ion for

"intermediate" pitch of future me t r i c s tandards) ,

(6) Varying washer ma te r i a l s , heat t r e a t levels, f inishes, and

dimensions,

FORM 4023

L O C K H E E D C A L I F O R N I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS REPORT NO.

C ONC LUSIONSfREC OMMENDATIONS (Continued)

( 7 ) 15 installation-removal cycles with and without added lubricants

and methods of achieving minimum variation between cycles ,

(8) Sealants f o r e i ther environmental o r d iss imi lar m e t a l protection,

( 9 ) Other fas tener mater ia l s . An example i s Multiphase (MP-35N),

a propr ie ta ry mater ia l of the Standard P r e s s e d Steel Co. Multi-

phase h a s seve ra l proper t ies that an excellent fastener alloy

should have. I t i s elevated tempera ture res i s tan t , h a s a very

low magnetic permeabili ty, i s very cor ros ion res i s tan t , hea t

t reatable to 260 KSI minimum ultimate tensile strength, and

dynamically i t i s a t l eas t equal to the bes t of the available

noncorrosion res i s tan t mater ia l s . It i s hoped that any f u t ~ r e

torque -tension t e s t program would include sufficient quantities

of MP-35N bolts s o that torque-tension relationship data for

this m a t e r i a l could be established,

Future preload los s studies a r e a l so recommended, The effect of

vibration on preloz~d los s in the joint needs to be determined.

FORM 4020

CONC LUSIONS /RECOMMENDATIONS (Continued)

Finally i t i s recommended that the data generated by this program be

reduced into a form m o r e readi ly useable, by design engineers , in specifying

installation torque l imits for optimum joint preload. Th i s information

shoi~ld be published in the S t r e s s Memo Manual.

L O C K H E E D ~ A L I F O R N I A G ~ M P A N V A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

iFiEv!S!oNS REPORT NO. LR 25049 PAGE NO. -i

VIII . PARTS TESTED

The p a r t s tes ted a r e shown in Tables I and 11. These p a r t s were

paired a s shown in the tables. The tables also show that the p a r t s were

t reated ei ther a s a tension combination o r shear combination, and the added

lubricant used, if any.

In some c a s e s the a s received p a r t s were only tested with added

lubricants. It was felt that these p a r t s should always be installed with added

lubricants in o rde r to minimize the installation torque requirements , and that

the adding of a lubricant would provide the m o s t consistent torque-tension

r,elationships between specimens and be tween installation cycles .

FORM 402D

TABLE I - Torque-Tension Tes t Specimen C ornbinations

::: Sources of manufac turer ' s p a r t numbers a r e shown below Table 11.

NAS6404U15 NAS129lC4M NAS6405U31 NAS1291C5M As Received NAS6406U 34 NAS1291C6M

09LH9074-8

NAS6404U15 LH7875-4 NAS6405U3 1 A s Received

As Received

MIL-T -5544 NAS6406U34 NAS1291C6M

MIL-T -5544

NAS6304U16 NAS6405U31 MIL-T -5544 NAS6406U34

MIL-T -5544

1 L O C K W E E D C A L i F O R N I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N 1 RLVISIoNS REPORT NO.

PAGE NO. 9

TABLE I (Continued)

Bolt Nut :g

P a r t No. I P a r t NO. Combination

Rating

Tension

Shear

Tension

Tension

Tension

Tension

Tension

Tension

Lubrication Condition

MIL-T -5544

MIL-T -5544

As Received

n/IIL-T -5544

:+ Sources of manufac turer ' s pa r t numbers a r e shown below Table 11.

I

1 FORM 4020

TABLE I1 - P r e l o a d L o s s T e s t Spec imen Combinations

s : ~ Sources of m a n u f a c t u r e r ' s p a r t n u m b e r s a r e shown below.

NAS1103-12 MS2 1042L3 NAS1104-17D MS2 1042L4 NAS1105-22D MS2 1042L5 A s Received

MS21250-05022 MS21250-06024

MIL-T-5544

l~lS21250-05022 MIL-L-23398

NAS6404U15 A s Rece ived

NAS6403U12 LH7875-3 NAS6404U15 LH7875-4 NAS6405U31

A s Received LH7875-5

NAS6406U34

NAS6405U31 NrlS1291C5M A s Rece ived

NAS1291C5M A s Rece ived

NAS6303U28D NAS1291C6M

FORM 4020

A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REPORT NO.

T A B L E I1 - (Continued)

NOTE: Al l f a s t e n e r combinat ions t e s t ed w e r e cons ide r ed to be tens ion ra ted. T h e r e w e r e no s h e a r r a t e d f a s t e n e r combinat ions tested.

::: P a r t Number S e r i e s Manufac tu re r

BMN4122 O m a r k

L,H10205, LH7559, LH7875, 109LH9074 ESNA VEP220555 Val ley Todeco 48FT , 69678, 696.80, 70718, 72914, 73178 S tandard P r e s s e d S t e e l

NAS6303U13D MS2 1043 -3 NAS6304U17D MS2 1043 -4 NAS6305U34D MS2 1043 -5

A s Rece ived

VEP220555-4-16 LH10205-4 VEP220555-5-22 LH10205-5 MIL-T -5544 VEP220555-6-22 LH10205-6

MIL-T-5544 7071SV6-23

MIL-T-5544

MIL-T-5544

L O C K H E E D e A L l F o o w i r i a e M p A w y 14 D I V l S l O N O F L O C K H E E D A I R C R A F T C O R P O R A T i O N

~ ~ E V ~ S ~ O I N S REPORT NO.

PAGE NO.

IX, TEST SPECIMENS

The t e s t specimens consisted of a bolt, a nut, 2 washers , and a

load ce l l assembled in a fixture. The load ce l l s utilized s t ra in gages so

that loads could be determined. These load ce l l s were designed to com-

pensate for bending and &erefore bending in the t e s t specimen did not

effect the load readings. The ar rangement of the t e s t s e t up i s represented

FORM 4020

F I G U R E I - T E S T SET U P

L O C K H E E D * C A L 1 1 F O R N r A C O M P A H Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T l O N

REViSIONS REPORT NO.

PAGE NO.

X . TEST PROCEDURE

All t e s t s were per formed during the period between September 1, 1971

and December 23, 1971.

111 o r d e r to preload the bolts to loads between 8 0 and 9 0 percent of

yield strength i t was necessa ry to determine bolt-nut combination yield

s t rengths. Two methods were permit ted. The f i r s t method was in accordance

with Tes t 8 of MIL-STD-1312. This involves loading the nut and bolt axially

in a tensile machine and obtaining a load-deflection curve. Bolt yield s t rength

was then determined using Johnson's 2 /3 approximate method. The second

method utilized the torque-tension test f ixture. Using a torque wrench, the

nut was turned on to the bolt in increments of torque. Torque and s t ra in

were recorded for each increment . Torque was increased until s t r a in readings

indicated that the bolt-nut combination had been loaded past yield point o r to

fai lure . In subsequent t e s t s the f a s t ene r s ,were loaded proportional to the

yield s t rength a s determined by ei ther of these methods.

Torque- tension t e s t s were conducted in accordance with Tes t 15 of

MIL-STD- 131 2 except for the following. Compression load ce l l s were used

in conjunction with torque wrenches to determine the torque-tension

relationships. The load ce l l s were calibrated and calibration cu rves

were obtained. Torque wrenches were accurate to within i6 percent .

FORM 402D

L O C K H E E D * C A L I F O R N I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVlSlOfqS REWRT NO. LR 25049

PAGE NO. 15

X. TEST PROCEDURE (C ontinued)

Countersunk washers were placed under bolt heads, and plain washers

were placed under the nut. Tes t specimens were assernbled in the tes t

fixture a s represented by Figure I. Torque was applied in increments

until s t rain readings approached values indicating that the desired preload

of 80 to 90 percent of bolt-nut yield strength had been reached, The

fastener was then disassembled and the procedure was repeated to obtain

a second set of datum points. Where lubricants were added, they were

applied to bolt threads and nut-washer interface in a conservative manner.

The bolt head was held stationary and the nut was turned onto the bolt in

al l cases. Three specimens were tested for each test condition.

The preload-loss tests utilized the same test fixtures. The bolt-

nut combination was preloaded to 80 to 90 percent of yield a s indicated by

strain readings. Strain readings were made a t one hour intervals for the

f i r s t eight hours, twice in the next 24 hours, and daily for the next two days.

Total time for each test was not l e s s than 70 hours. Application of torque

was to the nut with the bolt held stationary. Lubricants, where used, were

applied to the bolt threads and nut-washer interface in a conservative manner.

The initial s t rain readings were made while the installation seating torque

was maintained. The second strain reading was made 3 minutes af ter the

110CPdlHEED C A L I F O R N I A C O M P A N Y A D I V I S I O N , O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVlSSONS REPoRT NO. LR 25 049

PAGE NO. 16

X. TEST PROCEDURE (Continued)

torque wrench was removed f r o m the fas tener . Three specimens were

tested for each test condition.

A.11 testing was conducted a t room ambient tempera ture and humidity.

FORM 4020

A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

XI. DISCUSSION O F TEST RESULTS

The reduction of the test data was beyond the scope of this p rogram

and therefore no specific recommendations fo r installation torque l imits a r e

made herein.

Generally speaking the torque - tension t e s t s indicated that there was

considerable difference between the 3 individual specimens in a given group

and between the groups of specimens of each thread s ize . F o r example, fo r

a l l groups of . 1900-32 threaded fas teners , installed to 40 inch pounds of

torque, there was a difference of 1, 739 pounds in the induced bolt preload

between the lowest and highest values. F o r 160 KSI tension rated fas teners

this aznounts to 50% of the minimum ultimate tensile strength. This can be

attributed to the differences in ma te r i a l s , f inishes, lubricants, and the

configuration of the p a r t s tested. This amount of variation would indicate that

one set of general torque l imi ts i s not going to utilize each fas tener at i t s

optimum capability.

Pre load loss t e s t s showed s imi lar differences in the fas tener preload

a s a resu l t of the installation torque, however, the object of this portion of the

p rogram was to determine how loss of fas tener preload va r i e s in a static joint

as a function of t ime. It was determined that eve ry specimen lost some of i t s

preloa.d, and the los s varied between 1 and 11 percent . The grea tes t l o s ses

0ccuri:ed in the f i r s t eight hours af ter installation. The preload appeared to

be stabilizing by the end of the 7 2 hour observation period.

L O C K H E E D C A L I F O R N I A e o w ~ n i ~ v A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS REPORT N

PAGE NO.

XI. DISCUSSION OF TEST RESULTS (Continued)

The extensive detailed tes t r e su l t s a r e recorded in Almay Research

and Testing Corporation Report Number A5417, and i s available f rom

Locklieed-California Compzny l ibrary. The accession number i s 72-3296,

F o r thos6 interested in fur ther study of torque-tension relationships

a bibliography of recent publications i s appended to this report .

The appendix a l so includes an IDC which r e p o r t s the r e su l t s of a

torque-tension tes t on the I inch diameter VEP220555 bolts and LH10205 nuts.

This IDC h a s been included because this fas tener i s pa r t of the s e r i e s tested

in this program. Since the information in this IDC supplements the data. in

this repor t , it h a s been included a s pa r t of this report .

FORM 4029

REPORT NO.

APPENDIX

L O C H W E E D a C A L 1 F C ) R M i A C O M P L a a H V A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

iREViS!alNS REPORT NO.

PAGE NO.

L I S T O F R E F E R E N C E S

( 1 ) J. I. P R I C E a n d D. K . TRASK - T h e R e l a t i o n B e t w e e n T o r q u e a n d T e n s i o n f o r High S t r e n g t h F a s t e n e r s . B u r e a u of Nava l Weapons ( B U W E P S ) R e p o r t No. R U E - 343-61-1 . P r e p a r e d by t h e Na t iona l B u r e a u of S t a n d a r d s , A u g u s t 1961. U n c l a s s i f i e d

( 2 ) H. S. B R E N N E R - D e v e l o p m e n t of Techno logy f o r I n s t a l l a t i o n of M e c h a n i c a l F a s t e n e r s . Nat iona l A e r o n a u t i c s a n d S p a c e A d m i n - i s t r a t i o n R e p o r t No. NASA CR -1 031 79 (N7 1-26568) . P r e p a r e d by A l m a y R e s e a r c h a n d T e s t i n g C o r p o r a t i o n . 1971. U n c l a s s i f i e d

(3 ) H. S . BRENNER - R e s u l t s of T o r q u e - T e n s i o n R e l a t i o n s h i p S tudy 1 P r o g r a m of V a r i o u s S t r i l c t u r a l B o l t s a n d Mat ing Nuts S u b m i t t e d by T h e L o c k h e e d - C a l i f o r n i a C o m p a n y , B u r b a n k , C a l i f o r n i a . A l m a y R e s e a r c h a n d T e s t i n g C o r p o r a t i o n R e p o r t No. A5417 , I D e c e m b e r 23, 1971. U n c l a s s i f i e d

BIBLIOGRAPHY

Andrew J. Arnoldi - What ' s a Tight F a s t e n e r ? , Assembly Engineer ing, August, 1971, p g s 24-27

Thomas C . Baumgar tne r and F r a n c i s R . Kul l - Determin ing P r e l o a d in a Bolted Joint.

V

Machine Design, F e b r u a r y 13, 1964, Rep r in t

H a r r y S . B renne r - F a s t e n e r Specifications, Assembly Engineer ing, August 1964, Rep r in t

Robe r t A. Degen - Preva i l ing - Torque Locknuts - What They A r e and Where They Should B e Used,

Assembly Engineer ing, June 197 0, pgs 30-34

Robe r t A. Degen - Preva i l i ng - Torque Locknuts - What They A r e and Where They Should Be Used . . . , P a r t 2

Assembly Engineer ing, July 197 0, pgs . 28-31

Ralph J. E r i s m a n - Torque-Tens ion Relat ionships of Th readed F a s t e n e r s , F a s t e n e r s , Winter 1968/6$,

Volume 23, No. 4, pgs 9-11

Rober t J . F inke l s ton - How Much Shake Can Bolted Jo in t s T a k e ? , Machine Design, October 5, 1972, pgs 122-1 25

J a m e s E . F o i s y - Analysis of Nut and Bolt Torques , P a r t 2 I

Assembly Engineer ing, January , 1968, pgs 20- 22 1

Samue l C . Gambre l l , J r . - Why Bol ts Loosen Machine Design, October 24, 1968, pgs 163-167

F r a n k L. Gi l l - Bas i c F a s t e n e r Funct ions i n Envi ronments 1 of Mechanical S t r e s s , P a p e r p r e sen t ed a t U. C . L. A.

Extension Cour se , Mechanical F a s t e n e r s , F e b r u a r y 8-10, 1972

F r e d G r a v e s - F a s t e n e r P r e l o a d - Why?, Assembly Engineer ing, October 1970, pg 32

F r e d G r a v e s - F a s t e n e r P r e l o a d - How?, Assembly Engineer ing, November 197 0, pg 32

FORM 4020

L O C K H E E D C A L I F O R N I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

WEvIsIoIqS REPORT NO.

PAGE NO.

BIBLIOGRAPHY (Continued)

T o m Green - Select F a s t e n e r s fo r Fu l l To rque Research /Deve lopment , November 1966, P g s 38-40

T o m Green - A New Discovery fo r Controll ing the T o r a ue /Tens ion Relationshir,

Assembly Engineer ing, Ju ly 1972, P g s 42 -47

El l swor th M. Gunther - Assembly Simplif ication With Torque-Tens ion Nomograms

Assembly Engineer ing, October , 1969, P g s 36-40

Rodger Hansen - Reade r Feedback: The Turn-of - the -Nut Method (Continued)

Assembly Engineer ing, August 1967, P g s 18-22

A. G. Hopper and G. V . Thompson - S t r e s s i n P r e - loaded Bolts - Produc t Engineer ing, Sep tember 14, 1964

P g s 81-87

M. D. Hoza - The Turn-of-the-Nut Method Assembly Engineer ing, J anua ry 1967, P g s 16-19

R . R . I rv ing - Who Know's How Tight i s Tight I ron Age, October 3, 1968, P g s 85-92

G e r h a r d H. Junker - New C r i t e r i a fo r Self-Loosening of F a s t e n e r s Under Vibrat ion - SAE P a p e r 690055

Gehard Meyer , and Die te r S t re low - Sirnple D i a g r a m s Aid i n Analyzing F o r c e s in Bolted jo ints

Assembly Engineer ing, J anua ry 1972, P g s 28-33

Gehard M e y e r , . and Die te r S t re low - How to Calcula te P r e l o a d L o s s Due to P e r m a n e n t Set in Bolted Joints

Assembly Engineer ing, F e b r u a r y 1972, P g s 30 -34

I FORM 4020

L O C K N E E D * C A b l F O R 8 4 1 1 1 A C O M P A M Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS REWRT NO.

PAGE NO.

BIBLIOGRAPHY (Cont inued)

G e h a r d M e y e r , and D i e t e r S t r e l o w - How t o Ca lcu la te P r e l o a d L o s s Due to P e r m a n e n t Se t i n Bol ted J o i n t s , P a r t 2

A s s e m b l y Eng inee r ing , M a r c h 1972, P g s 28-31

W:P. McKay - P r o p e r T h r e a d Engagement by N o m o g r a m Des ign News , M a r c h 6 , 1972, P g s 60-63

C a r l C. Osgood - How E l a s t i c i t y In f luences Bol ted-Join t Des ign , Spr ing T h e o r y

Mach ine Desig-n, F e b r u a r y 24, 1972, P g s 92-95

C a r l C. 0 s good - How E l a s t i c i t y In f luences Bol ted- Jo in t Des ign , P r e l o a d and F a t i g u e Concepts

Mach ine Des ign , M a r c h 9 , 1972, P g s 104-107

E. B. P a l m e r - How L u b r i c a t i o n Affec ts T o r q u e - T e n s i o n R e l a t i o n s h i p s , A s s e m b l y and F a s t e n e r Eng inee r ing ,

S e p t e m b e r 1950, P g s 36-42

G e r h a r d S c h r e m m e r - How t o K e e p Bol ted J o i n t s Tight Mach ine Des ign , S e p t e m b e r 1972, P g s 140-145

C l a r e n c e R. S m i t h - P r e v e n t i n g F a t i g u e F a i l u r e s A s s e m b l y Eng inee r ing , P a r t s 1 t h r u 3 , M a r c h , A p r i l , May 1968, R e p r i n t

C l a r e n c e S m i t h - Reflec t io .ns , T e c h n i c a l i t i e s , and S m i t h -Kabobs - A s s e m b l y E n g i n e e r i n g , J a n u a r y 1 970, P g 33

C. F, S t e r n b u r g - F a s t e n e r P r e l o a d C o n t r o l C u r r e n t Technology - Lockheed-Ca l i fo rn ia Company R e p o r t

No. LR 22839, 22 D e c e m b e r 1969.

A . G. T o k a r c i k - T h e T o r q u e - T e n s i o n Re la t ionsh ip A s s e m b l y E n g i n e e r i n g , Oc tober 1966, R e p r i n t

FORM 402D

L O C K H E E D C A L I F O R N I A C O M P A N Y A D I V I S I O N O F L O C K H E E D A I R C R A F T C O R P O R A T I O N

REVISIONS

BIBLIOGRAPHY (Continued)

A. G. Tokarc ik - F a s t e n e r Sys tem Concept, SAE P a p e r 67 0889, Sep tember 1967

An Answer to Torque P r o b l e m s Product ion, M a r c h 1964, p g s 92-93

B a r e T i t an ium Bolt, A-286 Nut Lube Evaluat ion Standard P r e s s e d Steel , P r e c i s i o n F a s t e n e r Division Repor t No. 4976, A p r i l 28, 1972

Compara t ive Analysis of Envi ronmenta l P h y s i c a l and Mechanical Effects of Sur face Conditioning and D r y F i l m Lubricants on Ti tanium F a s t e n e r s

Voi-Shan Manufacturing Co. Engineer ing Repor t No. 459, October 21, 1569

Evaluat ion of Nut M a t e r i a l s and F in i shes fo r Use on Ti tanium Bol ts - Elas t i c Stop Nut Division,

-4merace E s n a C o r p . , Gctober 31, 1969

High Reuse P e r f o r m a n c e Ti tanium F a s t e n e r s E l a s t i c Stop Nut Division, A m e r a c e E s n a G o r p . , ER288-2929-2, Sep tember 4, 1970

How Dangerous a r e Sta t ical ly Loaded Machine M e m b e r s ? P roduc t Engineer ing, December 1971, pgs 37-39

Joint Des ign - Machine Design, Sep tember 11, 1969, pgs 12-23 I The Anatomy of a P r o b l e m : P r o p e r Tightening of Machine Sc rews - Produc t Engineer ing, October 197 1 ,

pgs 21-23

The Suitabil i ty of Var ious Coatings and Lubr ican ts f o r Use on Titanium Alloy Locknuts - Kaynar Mfg. Co . , Inc. ,

Kaylock D ~ R M L ~ ~ ~ C , November 18, 1969

FORM 4.020

LR 2504 Pg. 2 5 ,

Jh-ERDEPARThliENTAL COMMUNICATIC'N PE~O/ 5 22

TO 6.. W. I>cvis ORGN. ZONE FAC.

i DEPT.~ n-61 BWG./ 913 FLAK/ A-1 D ~ T E 7-28-.7~)

DEFT./ 77-16 CLOG./ PtAra/ A-1 EXT. 74943 ORGN. ZONE FAC.

W: Letter, BW~//~OU_-L~~I .~ , clat ed 6-39-70

Testa rre-re perforieil, as praxis&, to deternine the torque w,2..11s t o be specifiec?. for ,mbject bol t s . 3cs-ial.t~ of the t e s t s ran are a'c-trched.

If %re nay be of f'wther service, please

cc: J. I?, Jcnes J. A. Mrgan N. VerDjl Ip' R. Zelc-

@E F i le SPSP ( ~ 2 2 0 5 5 5 )

Form LAC 201

J. B. Bier5mre~ Group Lbgineer, Mechaicrja. Systms PELI*.~S md E Q x I ~ ~ ~ ;DQE~X%ILF%~

Pg . 26 ~ORQWT~~SION VEP 220555-16 m ~ o m

7u mm vs ~ ~ 0 2 0 5 - 1 6 szm P ~ 2 % XJT

b o det exmine the torque- t ension relationship of 1.0000-12 UNJF Inconel 718 bol t ad. s i lver plated ~ 2 % nuts.

XIOR: - me Ll4lll engine pylon attach bolts s are 1.0000-12 UlTJF thread size. m e bolts are ~nconel 718, part mmber 0555-16. m e mating nuts are p& nmuber ~ ~ 0 2 0 5 - 1 6 , n8de 12m ~ 2 8 6 with silver-plated threads only.. Data were noi; arvaileble i n t h i s combination of' s ize and nater ia l so that the pmper t o rwe t o provide the desired preload could be specified. Because of the cri1i;ical nature of the engi~.e a t t achen t , it was necessary- to perfom tcorque-1;asion t e s t s t o determine the proper instal lat ion torque,

19he torclple-tension t e s t s were pe,eo~s& at Valley-Todeeo, Inc. of Sylnar, California. I&. Gene lhikont ma 3 2 . Stmmt Bi~~zsds, under the direct ios of Mr, Rusis Sherman, performed the tes ts .

Test bol ts were over runs f'rm a l o t of production bol ts maneactured by V4aB1w-:Codeco. Test nuts were production nuSs disbmsed f2-an Lockkeed stock,

m%E: The IXLOZO5 aut should have silver-plated threads only. The parts dbt&ns3. f r o m stock had no plate. Ho%rever, the s q l e s used for these t e s t s were si:b-ver plated dl over a* VaUey-Todeeo, and the p M i q was rrsnwed From the nut bearing =face prior t o testing.

A &eac:ed aec t ron ics Cornpaany force washer, 1 in& I, D, ldodel Tao. 2016, was assembled on t h e bolt between hardened s tee l b t ~ s h i q s t o ac%just for the blolt grip. The force washer was aktached t o a s t ra in 5xdica;ting gauge, fStsdd P.-350, nmufactured by The isradd Co. k graph of the to rqyes t ra in relationship fo r 6 bol t of th i s s ize and mate r id hat3 previously been pswaapeh a d i s shown on Figwe I. The silver-plated nut was assmbled on t h e bol t , Zlke assembled bolt, force rasher, bushing and nu% as sab ly was then placed i n a 5 t o 1 torque a d t i p l i e s f'ixtuspe, Torq~~e i,%ms applieci in approxhately 75 fi-1% incswdeaai;~, using a P. A. Stmtev~?nt Go. torque t-mach, l~!odel irad. S-%OO (0-600 f%-1% range). Strain gauge sie&ngs were taken at each torque i n c r a a ' r ; a d recorded. 'P"he agpli& load wa;s then determined from Figure 1 . "Ie above t e s t was repeated except M I E T - ~ ~ @ lubricant tras applied t o the bol t th:read. This mssmbly w a s torqued. a d the results tabulated i n Table III and plotted on F i g w e 2.

LR 250 Page 2 Pg. 27

m e length of torque wrench am, 5 feet, made it impossible t o apply the torque continuously. fn some instances, between intervals, the wrench had t o be removed from the f ixture so&et and repositioned i n order t o Fully 8ppV the next increment of torque. This may a~cotmt for some of the erra t ic r e a s . In the first t e s t yielding in the system was observed near 1500 Ft-lbs of torque. Further application of torque produced a f a i l w e in one of the socket drive inserts i n the multiplier f x m r e . The t e s t was rerun asin&: the sane fasteners. The results of both of these t e s t s ase reported 3-13 Table I and Table I1 and plotted in Figure 2 . E"rm the graph it appears that approxinately 1250 fFt-lbs of torque i s required t o obtain 70,000 lbs preload i n the bolt when a silver-pltii;ed rrut, with no subsequent lubricant, ZB used. !Fads torque could exceed 1700 f i - lbs &er the f i r s t use i f the "'2nCt mx2" e r n e of Figure 2 was extended.

Ibe required torqie dropped drastically as ~ c ~ u l d be expected when MILT-^^& anti-seize lubricant was spplied t o the bolt thread. The curve of t h i s data Jinucettes only about 600 f i- lbs torque required for 70,000 lbs preload .in the bolt . It is e ~ e c t e d that some loss of preload would also occur i f this a.sseozb&y was reused. However, preload would probably be restored i f the bolt tms relubricated before assembly.

The engine t o pylon attach bol ts should be lubrieatecl pr ior t o a s s a b l y ~ . ~ i k h E ~ ~ ~ - 5 5 4 - & anti-seize a 9 l i e d t o bo l t %?areads. Pae assembly should be t o rqud t o 600 ft-lbs. The engineering instal lat ion clraaslintgs should be ~evimect and an instal lat ion torque, i n accordance with t h i s data, be specified.

33, above t e s t s were witnessed by the foUowing Lockheed personnel:

35x11 Jones Mike TTariDyl

Dept . 77-16 D e p t . 53-73

TABLE I

TABLE II

~~220555-16 Bare Inconel 718 B o l t - lKJ-0205-16 Sliver-Plated edt - 2nd RW (1)

(1) Socket drive sheared off af%er 1500 f"t-lbs. Test r em with s m e bolt emd nut.

Page 3

Load. I'b6X103

13.2 14.2 27.8 29.5 35 5 42.0 49 3 60.7 61.2 75 5 77-0

Load 1bxl03

20. Q 20.0 26.5 27.1 36.0 36. o 45.5 62.5 64.5 69.5 70.7 80.5 84-9 5

L& 250 Pg. 28

e seen in strain gauge.

VEP220555-16 m e mlt, Threads Coated with MIL-T-5544 Anti-Seize -

IH10205-16 Silver-Plat ed Rut

Strain Gauge Read ing &/In

Pg . 30 Pcnge 5

where T = Wrench Torque, in-lbs R = Wrench Torque ra t io (fron Table V?I of ~Nl'gb)

gbi = Beload i n bolt due t o tightening, lbs Ax = Root area of bolt, sq. in.

for 1.NKX)-12 mm:

B = 0.04993 for ~ ~ ~ ~ - 5 5 k 4 lubricaat = 0.06675 for &a~~-23398 lubricant

EJOTE: R values are for cathim plated s tee l bolts and f i t t i n g and are being used oIlly for approximation of t e s t results

s-8879) = A4156

R)i = & x 1 0 0 , ~ 0 ' p s i = 64,156 ibs or = '70,000 lbs

T = .a4993 x 64,156 64156

= 4993 in-lbs = 4.6 PC-Lbs

T = .04993 x 70,000 641%

= 54-47 in-lbs E 454 fb-lbs

T = .oG;675 x 64,156 64156

= 6675 in-lbs = 556 f i - lbs

T-T TESTS VEP220555-16 S T R A I N - ( I N . / I N . )

in bolt - s i lver plated nut

ome lube uninte'ntionally on n

Torque - F t Lbs x 20

FIGURE 2

L A

REVISIONS

I E E D C A L I F O R N I A C O M P A N Y A I R C R A F T C O R P O R A T I O N

DISTRIBUTION LIST

Permanent Holders

J. B. Bierbower V. G. Har t

. J. F. Jones V; D. Moss

K. H. Achterkirchen L. Celniker J. Hong A. W. ~ ~ a l i s u c h M. L. Kovnat

G. W, Tyree W. R. Zelenka I

D. J. Mackey L. W. Nelson

G. J. Reynolds R. F. Simenz