New Criteria for Self-Loosening of Fasteners Under Vibration

690055

Ne

Cr Un

Euro Europe pean an Rese Resear arch ch an re

Engi Engine neer erin ing, g,

epri eprint nted ed arch arch 1971 1971 from from 1969 1969 SA _Tra _Trans nsac acti tion ons,V s,Vol ol 78 by

690055

o r S e l L oo o o se se n n g

New Cr of Fa

ne

U n d e V ib ib r

on

er ar urop uropea ea

IQUE IQUETE

etho etho

an appa appara ratu tu no

to repr reprod oduc uc cond condit itio ions ns of vibr vibrat atio io to loos loosen en bolt bolted ed join joints ts bu cond condit itio ions ns

It ca

rs lo

that that ar no only only cert certai ai

hich hich also also clos closel el

si ulat ulat

be show show that that prop proper erly ly prel preloa oade de

resu result lt

rota rotati ti

occu occurs rs betw betwee ee th

atin atin

In addit addition ion to fati fatigu gu

on

thre thread ad an

.sur .surfa face ce of th fast fasten ener er an

th

clam clampe pe

offe offere re

fast fasten en ti

lo

th bear bearin in

for.t for.the he

lu in

lite litera ratu ture re

to mach machin in

that that ther ther have have been been th

an vehi vehicl cl

th

tain tain

in

tt

pt to

lain lain th se

rt nate nately ly to

to th icie icient nt

practi practica ca

th th tt

re

tate tate no

ar la

nd la

lo

form formul ulat ated ed an

in

or

pa re

r,

lf-l lf-l

in

),

ever everth thel eles ess, s,

(t

is th

extr extr

ia im

In

ti

ti

ta ro join joints ts

th

te ts

ai ly

here here

ig ll

el -l th

ne

in ch

reco record rdin in

paper.

tr in

pl tely tely

el as so

so-c so-cal alle le

affi affirm rmed ed that that tran transv sver erse se vibr vibrat atio io te ti

le

self self-l -l

il

de ri

ic

th

lo

te

ra

enin enin

in

le to

po

to

rf rm

is

io here here

this this ri

eval evalua uati tion on

is

gengen-

phen phenom omen en of self self-l -loo oose seni ning ng

ta

ts

is an

in

answ answer er to th

ua tita titati tive ve

pera perati ti

of

rrie rrie

if ic lt

os seve severe re cond condit itio ions ns fo self self-l -loo oose seni ning ng

give give prac practi tica ca

In

is

faste fastener ners. s.

ew test tests, s, whic whic

on

from from anot anothe he

th

Optim Optimal al Lock Locking ing of Bolte Bolte Conn Connec ectio tions" ns"

te

selfself-loc lockin kin

tr ly

Refe Refere renc nces es at en

affi affirm rmed ed

exac exac proo proof. f.

rota rotati ting ng loos loos nonl nonloc ocki king ng fast fasten ener er as ee

el as auer auer Le

*Num *Numbe bersin rsin pare parent nthe hese se desi design gnat at

ti

th thre thre

auth author or appr approa oach ched ed th prob proble le

ti

er ly lo

an Lynn(2) Lynn(2) have have test tested ed only only axia axia dyna dyna ical ically ly load loaded ed bolted bolted connec connections tions

nn

la

tota tota

in

SelfSelf-Lo Loos osen ening ing an

ro

-r acti acti

of la

erat erates es th

ween weeney ey (1), (1), as

lt

tw th

ro

In 1966 1966 th tr

answe answers. rs.

oodi oodier er an

does does

loading.

impr impres essi sion on

ti e, th re

xplo xplora rati tion on to de

rf

ould ould

tota tota Io it

with withou ou find findin in

ited ited

ti

prio prio theo theory ry an also also pres presen ente te

(4-6 (4-6), ), in

ta

it

corr correc ec solu soluti tion on to ta

is

th rela relati tive ve

asse assemb mbli lies es

ho ever ever give give th

an appr approa oach ches es trie trie

ti

In 1966 1966 Pala Paland nd (3 prec precis isel el

th

sign signed ed to prev preven en self self-l -loo oose seni ning ng of thre thread aded ed fast fasten ener ers, s, os of th exis existi ting ng lite litera ratu ture re

fo part partia ia loos loosen enin ing, g, whic whic

parts.

operation operation and effeCtiv effeCtiveries eriess6f s6fself self"loc "locking kingelem elements entsdederesu result ltan an seve severe re da ag

an expl explan anat atio io lt

os

of dyna dyna ical ically ly load loaded ed bolt bolted ed join joints ts

th re

ngin nginee eeri ring ng

self self-l -loo oose seni ning ng of thre thread aded ed fast fasten ener ers, s, they they have have

nd th

ater ateria ial. l.

an

the mech mechani anism sm of selfself-loo loose sennin

rela relati tive ve

betw betwee ee

co plet plet

actu actual al

fail failur ure, e, self self-l -loo oose seni ning ng is th

freq freque uent nt caus caus offa offail ilur ur is

ak it poss possib ible le

Rese Rese rc

n ke ke r

in

it

os ibil ibilit itie ie

il be show show an disc discus usse sed, d, with with

ABSTRACT----------------------------------------------------~-----------------he theo theory ry of self self-l -loo oose seni ning ng of prel preloa oade de tion tion

he subj subjec ecte te

an

ig

lf-I lf-Ioo oo test test

ui

etho ethods ds ar

to vibr vibrat atio io in to

desc descri ribe be

bolt bolted ed conn connec ec

is disc discus usse sed. d.

us

ilur ilur in

is

ne ly desi design gned ed test testin in

he sign signif ifii-

ta

pl in

id

lf-l lf-l

an

disc discus usse se in conn connec ecti tion on

ev lu ting ting lo

be appl applie ie

is iv

li ie it

posed. 314

in

ro

rtie rties. s.

th

in

to

th

achi achine ne that that yiel yields ds quan quanti tita tati tive ve

ro

le te ti

ll in

tion tion is pr

th ai

of proposin scientific im ifie

in

nd sophisti ated test

io

ethods yg

st•

It is

per-

form

se f-lo

in

se

thread is th sl

s.

se

seri

self-locking perfor

nc

te

se

lu in contact.

fina answer on th

ir ly

in

ss re

th

li

dditiona friction forces origin te from the'

of variou 3).

tistic

is

te

su ta le

lyin

Similar

st

fi

sl

se f-lo

in

been reached rise betw en th HE

CH NISM

th ll-k

is

la

lf-l ic

tw soli

external forc

in on directio

orki

th

ss ll

odie

le

an ad itiona

th

forceQ is

iv

ll

tan(-cp

le

he bolt coul

th friction

ta

P)

tan( -c

P)

(tan -c

1.15 fl)

fl

DH fl

lo se by itself (without th

ff-t

ly

To

applicatio

re

it

(1)

th sl

th so id

lo io

f-

ti

r,

th

in

th horizontal pl ne re resent th

th

'"

tw

ri

"F

forc

show weights, whichcanberegardedasasim

pr sent th thread an

contac surf ce of

foll

ove-

ri io

is smalle th

angle. Fig.

rts.

rc

is

ll illu tr

thread fl nk an th

la

fe ts

ti ly sm le th

in

in

se in

friction forc betwee

rc

la

F- OOSE IN

to th

fe

th

re tl

fr

st tr

ro

L·tan

ly Fig.

QJ

(~IP)=

im if

-L·tanlp lt

in

ibra io

OJ

tan

(-Ip

tan

conditions

te 315

in

st ic

ti

316

G ER HA R ro

ti

lu

id

ll

lu ri

te

re

th

ri

diameter (equivalen

ro

th

th

is,

if th

m.), he specifie values feirthe relative

3/

ro

SjF

io faces, ha been very

idel

owever if relative /o

th

in

rt

ic

is it

il

ta

ti

rf

th

la

tern

rc

th

ra ial. th

ri ti

th

in

ir

ll

ts

th

of heav

oc ur betwee

ta

re

(Fig 4)

eneralized

otio

(4)

preloa ry

rf

ts in th

ti

to

to,

U NK ER .

10 proximatel

la

tr

thread friction angl will

co ditions, th down to

rf

H.

ra ia

is la

ld'ex lain

la

(3). in

it

lo

in

in

impact loadin

threaded letely lo ir

ti

lt ir

(1

:th

ti

re ti

ie

re

ti

luti

ro im tely

/4 in

This

t-

lt

everthel ss

to

ti

te

this loosenin

ha

il

alread

te ti

in

caused

preloa

ro r,

.th circumferentia

friction forc

resistin

th existing internal

off-torque is.

(6 lo

ti

in

in

(3)

re te

late

rotati

lo

in

relo

le

iu

/1

te ti

th

SIP/a

lo

-<

ti

ts

t-

maximum

le

in

ir lo

le

rt

lt

rkin lo

rd

,0

lt

in

in

it

in

rv

le equal

ti tw

is

th

thre

la

la

la or axiall

lr

lo de

rt joints

th

connection create rf

lati

th

in

inte

ri

th

ta

ti

rf

S:8

th this re

r? oodier an

ls ti

te

radial slidin re

ti

la

otions betwee this re th

ti

lt th

tr

tw

ti

ll

ri

th

ta

ti

th thre

la

th

relative

ta

rf to th

tr

ti

rs

lo

in

icti

rt rith

420/0.

thread

ri rule

relo

or dyna ically transverse loaded joints th

eene have

io

th

ic

th

lF,t

to

ri ti

ri ti

rc

rc in

tr

itte

tw

li

re

axi-

th th

la la

in

tr in la

rt

thus betwee

rc th

th

lt to

lu

thread flanks

litu

tr

rs

li

in

li

th

lt

tr

rs

is

rt

th

thre

th

the internal off-torque forc

re ti

tr th

joints Toff i~Y'T'

tan (-¥):-

is usuall

rs

lt

join

tr

re

re

in

ra

xperie ce show that thes

os frequently fail by self-loosening le

lf-l

in

is th

te in

th

y'

driv shaf transmit ig

li

ac epted.

beco es sufficient

rs

ibrati

th

omen

to th

crow

heel

ro

317

S E L F- LO O S E N" IN " G O F F A S TE N FR S th

iffere ti

be

th thes

ea

it ofte

ro

nd

tw te h.

ur

ch re

sv rs

slippa

ro nd

re

by themselves.

ua ly in contact, becaus

adjacent bolt connection is

th

th tr

re

av ly

ad

th

th r. It onslst ested.

deformatio

la

ic

la

turn

tr

by he fast

sv rs ly lo

yn

transverse slippage takes

on th crow wheel.

in the

de ring th rotation

th

the

ro

~e

on bolt

te

th relati

emen

plates (cause by th

tw

th

tw

pe

transverse loading) wa recorded by

the he tightened. both bolt torque

high spee recorder

the join is axiall ca

cu be ti

or coaxiall

se su

th

loaded transverse slippage

oa in

la

us

rt (for

pl

lastic

for-

.be ri

co

ul be ight ne r)

prop rl ti in th

in

nism

determined

tr

sv rs ll

Schoellham er

lo

joints

of th

aboratorie of Daimler-

Benz AG., Stuttgart. ha determined th of severa fasteners. includin nami

transverse loading.

transv rs

pa

ff torque oose

re se

thou th

hese test

self-locking type unde dy es

st th fr

to th

of

ibra io

in

nc

ha th

ter-

fina ly rotate

tern

off-torq

ac in

ua ed im

in

te ro

relo d. join

ibrate

ss th bolt

loos

external off-torque wa

induce

transverse force. th

it

wa no determined.' frequenc

ther increase of induce

external off-torque de

vibratio

values indicating clearl lope

Fo

by he

roof fo th inte na

th relative

re

Whena certai

it increas-

Toff

th th fast

rs indu

torque

dur-

th

easured.

corded

This

that ther

dg

fe

ua impuls

is

an internal off-torque

th

li inatio

ff-torqu

resulted in negative torque iall

of self-l

easure

lo de

king

of -Q.58m gf (50.

thre iv

en

inv-lb) wa re

internal off-torque wasapproxt

ff re ti lrte

he

external off-torque

th fast

ssit

se ir

In

nc as

br io

necessar

si

to he

(5)

(-cp)

relo

it increasing

as reached, th external off-torque fo loosenin center of

torsiona vibration.

TO PREVENTSELFLOOSENING

r----

rt

-

re

it

lock

washer

BYMEANS OF DESIGN

--

it

1 ) 1 )

rdin su

re ious esea

at tota se f-lo se in

rk it as to do

sjoints ha

~.

~.

thread islargely diminished by th

\~

of an alternatin

workin

load

rtia lo se in

."""

th

intern

he loss

off-torq he

relo

ca se he tota

co pression amplitud

ot ti

le

to

is roportiona to th in re se nt

he

lt rnatin

furthe loss prel ad ti

hi failur

orking load (a ial)

is

ig

oose in torq

fo

relo

fast

rs

tr ns

th

tota

ro ti

in transversely loaded connection

lo sening ca

oc

as soon as th clamping

G ER HA R in tran vers

slippage

twee

th

la

part is

it is

used

ot

nd to

ip ri io

ly by tr

curs

rans

ai tain su icie

deal with th is

te

sv rs load or tran vers

th

lo d.

U NK E

this paper

in

"self-loosening" branchof th failur

esig rule or

of pr lo

om

la pi

H.

partia

oi in

self-rot ti

ech-

lf-loo enin is

ll

lo .De ig in th

la joints th

re lo de

centricall

The proposed concep of th self-rot ti

of

eari

th

icture

by introducin

th

"self-rotating

ti ue ailure ic

betwee

ca s)

lete

se re

ch

unde

re ains

ol

an

ni

th

atte pt is

ad to illu trat

dy amic ll !; lo de

ig

th failur

bolted conn ctio

(7).

hhi

il re

(i re

illustration showstha th atig

br

eddi

of preloa

en

values afte tightening

na (S tz n) du to pl ti th

la pe

rt

de

is ta

basic.rul

(transvers load/frictio

T/Jl

ci nt

to

ke

od rn rule ar

therefor

re th

or

on th

de re

pr lo

tr nsvers

lc lation of olte

base

ti at

of th

th

necessar

of

bt in

ddin by ti

lipp ge an oc ur conn ctio

(8

residual clamping force, (S tz n)

te in

coeffi

nd th

catter

as re re nt

in th

following equation:

f-l ithe

scatte

were prob

th it

he th

fastener co ponents.

sufficient residual clamping forc

rm ti ns of th fa te er

bvio sl

ably caused by partial self-rotating. ig

thread flanks of th

is

ld

deformations or even by insufficient tightening In

th

to

This requires that

echanism of self-loosening

st ners

failures unde vibratio ro es ."

ri

ll

fo avoiding bolt failure,

kage or by self-l osenin

is to

pply

6F

max

(6)

where:

(7)

th

if re

rs re

sitwas previously shown,usingth exampl only if th

join fastener

ar

uneconornicall

th lt

onne ti ns

re th

relati

re

ende

eyon

ovements

te

to resi

of fastener th

crow

overdt en

ic ll ex ct anno

lc lation

lway

In thes

co

ofth

th re

cl de

by

cases, us is re-

with self-locking elements that

intern

ff-torqu

hi

occurs

he

inherent self-locking is lost PROPOSEDNEWTEST METHODS

AND

M A CH IN ER Y ince relati

ve

nt

tw en cl

ed part

fastener cannot be avoided by only an ti

jo

self-locking fastener have to ro

effectivenes

of such self-locking fasteners. Severa test re in

cert in

pe ifie

condition ra

lu

ig

so att

type of lockin

ta

ta

lo

ondition

ta (s

npreload

in

re aste

ti rs

th

th

in

co diti

).

reload It is bvio

re ther sp ci ic ti

iv

al es

319

SELF-LOOSENlliGOF FASTENERS fo installation torque breakawa

torque an

prevailing

torque.

th

it

this pa er an entirely differ nt approa

is prop se

Since transversel loaded joints·tend moretoself-Ioosentng, th

test ro edur firs

sugg sted imitates th se actu

tt

re

ts la

th

th

an

displa emen

an

displacemen •.

th

pick

ll

ib

it

lu

th

-s

si

fi

external thread

it

ay be used te st

is se

sure

ts

it

ro

le

le

tric

th

.fl

tw

stri

to

specia li ea diff rentia

tightening an loos ning angles ter.

ic

flexible shaft. increase

sp

itte

to

te ti

tr ns erse forc

st

ee le bearings to void galling.

type offatigue test th

th

hell testin

is is

iv

ld io

se fo th

re

re

le ents

lt th

ld

bolts.

relo d.

displa ement.

It

is in

bushin

sw se rg

in fo testin

sh

The"force is tr

transverse lo d.

ti

lo

sh

th

differen fo th variou lo king

ro

s. this

isti sp

to re or

he prod ct transv rs forc ca tl

onditi ns

si

internal thre ds is lace

is mea-

transfor ers.

re

tt

asur th

ch ng able thread

he

it

linear

sp im us in

nd insert

in re sing fr qu nc 5/8

st

init

tartin ff

xi

nerg

fo

(a

lockin

as ne essary fo rotation loos ning

Th

elements. machin

is

which is signed fo thes tests.

an differen pulley

allo

testin

frequencie

of 1500 3000

4500 cpm. in chin

generate

resultin tiff

ss

stri tl

tr ns erse forc spri fu ctio

Fig.

transv rs

st

slidin

otio

et ee

is in ep nd nt of fr qu nc lo

ra sm ttin

th ec entric adjust

nt

sh

thre

diff re

nd rts)

rrange U-shaped shee

nt is used fo test

fo th

achine

la

th

s.

th co ne ting plat

th '....

is

transverse

fati ue strength of bolt

interest if th fast

teners with serrated bearin is

pure transv rs lo d-

Uvshaped

it

sp

it

etal specimen that transmit th

forc it this rran emen

C ON N EC T N G P LA T CE FO R AN S VE RS E ORCE

pplication

tw

surface.

in

shee

rf in

In th bottom pictur

32

G ER HA R

any combinatio

ing the xi

H.

U NK ER .

of transverse recordin

methods, th

testspecimens were restricted

in

.. in X-

ns

hookup

om

cpm), the

-Y FT

dl

of of elf- ocking

he

fa teners is in

multipkled

....._____

.: -c

';;:

.:

$P1;

....

O lS Pl AC E ME N T

ADJUSTASLE EXCEIITER

RECORDER

L OA D C E FO I'RHOAD

S HE n

M ET A

S PE CI ME N

B RI DG E

A HP L F. FOR

PRELOAD

B RI D E · A MP LI F FOR

F.

POTENTIOMETER RECORDING

COMPR. LOAD FO

vibratio

machin

TRANSVERSE

DISPLACEMENT

to

SE F- OO JmIN

321

OF FAST NE

type an th

echanica

lo

size MIO test result

om

it

lain

sh rs

urin

that thei

of scre

ti th

ha in

ness of 771\ (HBSO:::13 kgf/

).

ck

ll

rs

re

itio

al test th specimen

kgf

re

rs

fast

rd":

it

stre

pt thos

IS IWl

er run

Teste

Specimen

------~~~~--------

Dimensional Specification

Scre

';I! a3 ,c:~ ,: ;.s~

30

Thread ton Bolt 6g Nu 6H ominal

ax thread

ll

0. 0.01355 in

screws

tc

.5

196 Series, ominal ll

ax thread nc

0, 0.01142 in

oc

scre s,

1960 Series.

.586

Threadtole

lt

in ll

thread nc

0. 93 '0.00759 in

Spring

ashers IN 33 (AI) lu spring

ashe

IN 12

Free Spinning Lockin Screws

tols Bolt 6g

Thread screws, MI it

1.5

30. ominal

triangular teeth,

ro ve

ri

lat-

ax thread

ll

0. 44 0.01355 in t6

screws, M1 it

lo

1.5

30,

ra ia te th

and circumferential

curve

on

ll

nc

0.34 0.01355 in

ri formin

nwash rs

continuous

originally.preloaded lass 8.8(si il it

to

sp

pm,

PLOTOF TRANSvERsEFORCE AND DISPLACEMENT

io

Socket head ca

test

750/0

th ie

ll test

drive (1 cp

er

This

5500 lb

Grade 5).

X-Y

he free spinning

onlockin

ll

of higher hardness (R

properties in Table 2. Screws of th

.s

in

GE HA

322 ,(HYSTERESISCURVES)- Th placement

in

schemati

drawin

slipping bolted'connectlo

force/displace en

diagra

subjecte

twoplates

U NK E

in to

dy

tted line represents th

amic transverse forces

H.

hich ar clam ed

is larger

in

th

therefore th

threads

lo

in

soli li

er

li

is lace en

in th

absorbed friction energy is larger too. ia am re esents

join

.i ha

th

,T

in

ef re thread slip in slip in

an

th

sc ew thread is

rted

th

site

ca

pr ceed to

(f

narrow thread

tolerance) or to

is

is being transformed into

ly th scre

ea

li

re te

is

last

force/ is acemen

fricti

rg

th

en

tan

CP),

ef ecti

ia ra

te its

fo

arin surf

ic

e.

th

th

ea

ar ad

here slip in curs

distance

ec

ca

ro

as ener rotati

becaus

rt es

in

only ther

ca is th

ta

lace

scre

re

lyonth se ri ti

ecimen

HV

Proportional Limit.

UTS,

kgf/mm

kgf/mm

(Dia on

e H

yr 30 load

e H

Remarks

Al 11

117

156.400

166,400

156,400

166.400

360

270 .96,600

Mech, properttes

6f--

116,600 275

119,500

133.700 (0.00197 in.) from surface

85 120.900

139,400

Ai.

F- OOSENING

OF FAST NE

323

fo thread

it

ex-

0:: III III

cc rdin

to

ig 11.

III

5! 0:: 0:: LII LII

(F

-e

f1

LII

0IL

FT

co S PL I

AG

HR AD

O NL Y

.C

is OOjo

unde transverse vibratio Fv%

60 40 20 O,

.0

0,2

.0 500 400 300 200 100

rs

forc

FT er

is la

200 300

spinning lockin

scre SPECIMEN

500 [K f]

SPECiMEN

C2

G E H AR D H .

324

U NK E

starts to fully

with er

force/ isplacemen

hy eresis

urve

It

with the

lt 4 0 0 / 0 of the

represent the load/deflectio

curv

0.36

prel ad an during 10

machine. Fig. 13 shows the

unct on

angleofrotatton

isplacemen ll free pi ning

of

X-Y erie de ribe late Fig. 15 shows the first 50

10

)IJfo

10

cp

frequenc

200 cycles,

Fig. 14 adju tmen (z ro load amplit de

do

±0.8

0an

14.40/0 respectively

the angle

3000 3000

cpm,

intoconsidera-;

and is approximatel 20 in several tests independen of frequency.

30

It the fo ce

of th frequency. In luence th loosenin

Fig. nonl ckin

the

au ng he

oc-

cycles. the

ta in

crew AI freq ency 10 cpm

tops an

deg

fur-

he os of prel ad is due to surface.

relative

50.

by the

roce

FV

roce

0.6

FT

14

AI frequenc

3000

cpm

S EL F L OO SE N N G

OF

A S TE NE R

325

ex-

als show clearly te es

the hys-

ac eriz st re is

rv

li

co

(10)

thread slip-

ts th

recorder

11, which show

imitin

lu

the exceedin is

ri

il

ited fo

lu ti

ta in

used.especiatly th

-Y

ited

lo

st

io

lockin

te ti

re

ci

ar

sp ce en

ll ·Fig 16 sh

cill scope. ac in

to

an

actual

T-

VlBRA TION

rg lute

axim

re re

re

tp

of th

st

ctio

transverse forc te

ia am stif

fr

sVi rati

tr

th

ll

rb fo

th

absorb exactl in lu

that

ar

in th ex re

rictio

re

ce th pr

ct

ti

rtance

if

tota se aratio it

so ed

smal

re

transverse forc

rc ro

ti es

ll

se to in

is lace en

rg

en su jected to transverse displace ents ,.,rillbe called "vibrati

in

rm

is lace en

/4 cycle:

in

roduct

he pr

"d an

sico th

tw

th th

re

lt

fr

ay

rst.

Twere recorded on

transverse forc

er

ct

V. tain

fo "d

relo isic

er

lti-

(8)

electrically trem ,,'_'

in co

emen s,

and

/4.c cle,

of eq al im

ep fr

ib ti

se

d·F

_A

th al es ar

will

steresis curves

slips under alternatin te si

ra

to rotate

transverse forces in connection with relatively smal

as larg er si

elements

i. Slipping joint

since

ie at

ca se thepre loaded scre

ro

esti

'be

co er

ar

in ll

ll

transverse force.

is la em

ic

th

re

fric io ),

ul absorb

ltiplyin

is lace en circui

as

an

il fr

ulti lyin

th

si

al

th

tw am lifier

transverse force. co

"d

ercially

ltiplicati availabl

an FT electrically

co

onents

it was possible

(9) _.

·I

.,

asin

. . , I : ,: ,: ,' ' - ; ,, ' .' :~ :" .

th

¢: 0n case th

ener

fo

full cycl

ld

ti

te in

lo

re

an rotati

im ta

lo se in

an le

sl

as re istere

as

zero ..

QQ_

Fv%

Kgf

lOO

0,8 0.6

lO

SO 10 SO 40tf 300 200

100

100 200

vers

300

forc FT versus displace

1,00

le

SO

in

cz

ib atio

self-l ckin frequenc

-.

fo fr scre

10 cp

v. _-

_ _. . _ -

and

326

G ER HA R a)

tan ••

,"

91

rd

~=~

,8T·

H. lo

st

ti

(s

01

t)

angl

Kgf/

fi

(1

re

the

it

potentio eter an th

scre

subsequently

to 1000/0 preload. 17 sh

recordings obtained

loosening settings

fu er

ti

th

djustmen

frequency (pro

so

tota

as descri ed

bo e,

re

as follows: ccentric

ma 00

lb

th scre

recordin

tightene

U NK E

to roduce

3000 cpm,

in

).

fo

ig

sh

afte on tighte ing. test

'" 210

the screw retain b)

M2

T02 . . F l IE

02

lo

500/0

M1

th

2d "0

te

00

s.

rotation lo sening an th

re

angl

corr sponds to the

£t:t!.d0!2.2~ -w.•• unserrat

scre

of th

sa

di

nsions is

If

loses 120/0 pr load

partia

rotation loos ning

nd 3fP/o by

in.), whic

re th

(C)

se rate

02

0. 06

.)

ig

scre rese

sa

si th

s.

ff r-

th

ture sh

th lo

unde th sa

r----

corre

ti

in

conditions

ss xcep

is

te

it

l02

so ti

sm le

te

ti

rm

non is

ic

d)

M2

M1

m•

ma•1

CM~d

ff re

hard washers.

is se rotate

In this

ic

-~.d

sh

th

lo

lo se

in

nl

st

'fi. Fra2

"y

'FlO!

fasteners reported in fere

rg

le

ls

it

eccentri

positions) re ording preload.

an vibr tion product. th latter co pute

produc

ei

displa em nt an

st ngle of rotation th

el ctroni ally

transverse forc to descrlbe th

test procedure. actual hysteresis curves

th

erformance

f.

lockin

le

nt

isadvant ge

eing

SELF-LOOSEl:'lINGF FASTENER

327 va

SOF

WASlfliR

X-

CYCLES

-

'5

00

rs to

l;?'

pr 7D

ANG\-E

III

in th

ia

it

nd

le tr ni

ly or la

ui

t.

ltipli

ti

ratori

testin

ll

re

ires

-Y -Y

recorder

an

li

ot

tiom te

tronic re or in

ic

is ne

circ it

on elec

le

.

si il

if

tu

el

ib

ro

ed

io ts

:""""-;--+----t

re

III

.

lS

----t----!----:7'?r---;;H---+----t'O

,.

3001+----t-"7'~---1--7"-_ ---,-----t6

in

it th

ib

th re

ibrate

loos

toti

ll

in

pl tely ibration pr

th

rv

re

uc valu

es

ic

ea ro

'"'"

rv

It:

xi

'" 100

S OF T

III