Cov Khoom Siv Hluav Taws Xob
Most khawmdaim ntawv thovyogtsimrautxhawb nqa lossistransmyog li ntawdme daim ntawvntawmsab nrauv thovload.Yogthe zogntawmthekhawm risyog thekev txhawj xeeb xwb,thib erefeem ntau tsis muajxav taurausaibuayua ondcov pa roj carbonhlauTshaj
90%ntawmtag nrho cov fastenersyogmuantawmcov pa roj carbonhlauHauvdav dav,covderingthetus nqi ntawmrawmtsev neeg,tsis-ferrousyuav tsumuacovdua tsaugtsuas yog thaumadaim ntawv thov tshwj xeebyuav tsum tau.
Tensile Zog
Covmost kev sib raug zoomib echanicov khoom ntiag tug cuam tshuam nrog sawv ntsugard threaded fasteners yog lub zog tensile.Tensile zogyog themaxi uamumnro-thovloadthekhawm ristautxhawb nqa priorraulos yog coincidingnrognwstawg(saibdaim duab1).
Tensile load lub khawm khawm tuaj yeem nrogtthiabyog determinua edua by theraumula ua
P = StxAs Example ua(saibdaim ntawv txuas ntxivrauStthiabAsqhov tseem ceeb)
qhov twg 3/4-10x7”SAEJ429Qib5HCS
P = tensiv load(lb., N) St=120,000psi ua
St=lub zog tensile(psi, uasMPa) As=0.3340ua sq.nyob rau hauv
As= tensile stress cheeb tsam (sq.in, sq. hli) P =120,000psi xwm0.3340ua sq.nyob rau hauv
P =40,080lb.
Rauthyog kev sib raug zoo,aqhov tseem ceebdkev xavmust yogmuabrauthetxhaisntawmthetensile kev nyuaj siabthaj tsam,As. Whibatus qauvthnyeemkhawm ristsis nyob rau hauvdawb huvtuairau,it kojpically f kevturesthntxhibthethnyeempoj porti uaon(thyog characteristically nws yog smallest cheeb tsam).For thyog reasnyob rau,thua tensile stress cheeb tsam yog calculig
thntxhibibempirical raumula uakoom nrogthetsis muajminua diamlwmntawmthekhawm risthiabthethnyeemsuab.Cov ntxhuav qhiathyog thaj tsamyogmuabrauyou uanyob rau hauvthedaim ntawv txuas ntxiv.
Ntawv Pov Thawj
Daim duab1 Tensile Stress-Nyuaj SiabDaim duab
Covpov thawjloadsawv cev thesiv zogntau yamraupaub tseebtus qauvkhawm risLos ntawm kev txhais,thepov thawj loadyog ibthovzog loadthob thekhawm rismust kev txhawb nqa yam tsis muajmnce deformation.Hauvlwm yam
words, the boNws returns raunwsori uaginua al shape nyob rauce ua the loadyog removed.
Figu uare1 ibmobustrates kojpical kev nyuaj siabsib thamnyob rauship xovofa bolt as kojnsionloadyog app pajdagd. The steel muaj qee yam amtus nqi ntawm elasticity raws li nws yog ncabed. Yogcovthauj khoomyogremnojthiabcovkhawm risyogtseem ntsehnyob rau hauvthua elasticnge, thua fastener yuav nco ntsoov rov qaburn uaraunwsori uaginua al shape. Yog tias,hopebvrau, the loadapp pajdag vimthekhawm risrauuacoj yav dhau los nwsyib ieldtaw tes,nws tam sim nonkag mustheyas ntau yam.Ntawm no,thehlau tsis ntev lawmmuaj peev xwmrovurn uaraunws original puabyogtheloadyog remnoj.Covyib ieldlub zogyog thetaw tes rau qhov twg permtsis tauelongationtshwm simYogpebwuatxuas ntxivrauthovathauj khoom,pebyuavncav cuagataw tesntawmmaxi uamum
kev nyuab siab hu ua ultimnoj lub zog tensile.Yav dhau los lub ntsiab lus no,covkhawm ristxuas ntxivinuvrau"Caj dab"thiabncua ntev
1
furt uaher nrogib reua duua ctionnyob rau hauvkev nyuaj siab.Add uanwsnyob rauua stretchingyuavulti ibmua cause ua thua fastener uabrovob the lub zog tensile.
ShearLub zog
Shearlub zogyog txhaisraws lithemaxi uamumloadthntawm canuatxhawb nqaua priorrautawg,thaum twgthovntawm lub kaum sab xisrauthetus ceevaxis.Aloadtshwm simnyob rau hauvibtransversedav hlauyog paubraws litib leeg xwbtxiav.
Ob chavtxiavyogathauj khoomthovnyob rau hauvobdav hlauqhov twgcovkhawm risyuavuatxiav ua peb daim.Daim duab 2 yog
ibexa uample uantawmob npaugtxiav.
Raumost txujthnyeemkhawm ris,txiavlub zogis tsis aspecificati tsinyob rautxawmthuvtheua fastenermaw be cohlitsuas yog sivnyob rau hauvtxiavdaim ntawv thov.Whiav shearxeemntawmdig muagrivets yog azoo-standardizedcov txheej txheem uas hu rau ib qho kev ntsuas qhov ntsuas ib zaug, testingtxheej txheemntawmthnyeemkhawm ristsis yog lizoo
tsim.Mocov txheej txheem stsivaob npaugtxiavteeb,tab sis txawvnyob rau hauvthexeem teebtsimuaib davtawgnyob rau hauvmyooj yimtxiavmuaj zog.
Raudlwmmine the shpob ntsegngth uaofthe mqub, the totib cross-cov sectinyob rauib alrea ntawm lub dav hlau shear yog kuvmtus yam ntxwv.Rautxiavdav hlauthntxhibthethnyeem,pebyuavsivthesib npaug tensile kev nyuaj siabthaj tsam(Raws li).
Daim duab 2 qhia txog ob txoj hauv kev forcovthovtxiavthauj khoom.Ibhascovtxiavdav hlausib raugnrog the threadua edpoj porti uaonofthe bolt ua.Since ua shpob ntsegngth uayogdncaj qha ntsig txograuthe nthiab sectinyob raual area, uasmlwm yam
cheeb tsam yuav result in iblower uabolt ua shpob ntsegngth. Rauta uake full ib adv xabanta uage ofstre ibngth uaprop uaxeb, the pxa mus rau tsimyuavuarautxoj hauj lwmcovpuvntsaglub cevnyob rau hauvcovshear dav hlauraws liqhianrogcovsib koomnyob raucovtxoj cai.
Daim duab2ShearDav hlaunyob rau hauvaBoUa ltSib koom
Whibtsis muajtxiavlub zogyog muabraucohlinyob raucov pa roj carbonhlaunrogtawvncerau40HRC,60%ntawmthua ultimnoj lub zog tensile feem ntau siv ib zaug muab rau ib ceable kev nyab xeeb.Qhov noyuav tsumxwbuasivraws liib estimati ibnyob rau.
Qaug zogLub zog
Akhawm risraugraurov hais duacylus lotshaj tawmtuaj sai sai thiabpoob nthav poob nthav,txawmyogthelotshaj tawmyog
zooblwm elow thua strength uaofthe material.Thua fastener tsis infatigu uae. Thua fatigu uaua strength uayog the maximum zogakhawm ristautivrauateevnuj numberntawmrov hais duamusua ntejraunwstsis ua hauj lwm.
Torsional Zog
Torsional zogyog aloadfeem ntau qhia tawmnyob rau hauvter ibmsntawmtorque, covqhov twgthekhawm risua tsis tau los ntawm kev sib twtawmtxog nws cov axis.Kaisntsia hlauthiab ntsaws teeb screwsxav tauatorsional xeem.
Lwm Yam Khoom Siv Hluav Taws Xob
Hardness
Hardness yog amkev yooj yim ntawm amaterial lub peev xwm los tawm tsampuasthiabindekev xav.Rau cov hlau carbon, Brinell thiabRockwell hardnessxeemtauuasivrauyogmnojlub zog tensilekhoomntawmthekhawm ris
Dukev muaj peev xwm
2
Ductility yog ameas ibureofthe degreeofpqhov kawgdua eformati ibonthntawmhraws libib eensustai uanua edntawm qhov tawgure.Hauvother wbords, nws the ability uaofa material raudua eform uabua eforenws tawgures.A material thua exp kevuancesvery txior
tsis muajyasdeformationraws litawgyogtxiav txim siabbrittle. Atsim nyogqhiantawm tus fastener ductility
yog the pivofnws spzoo siabminimumtawm losstre ibngth uarauthe minimumte uansiv strength. The lovaw thyog piv the moreua duqig thua fastenyuav yuavbe.
Kev nruj
Kev nrujyogtxhaisraws liamaterial covmuaj peev xwmraunqusimdaim ntawv cog luslos yogpoob siabchaw thau khoom Kuvmdaim ntawv cog luslub zogtawv
tsis tshua muaj qhov tshwj xeeb xav tauemnkag.Dhau lintau yamkev lag luam aerospacekhawm ris,ASTMA320
Specificationfor Txhuaoy Hlau B.olti ibngCov ntaub ntawv forTsawg-Tempkev sau ntawvKev pabcuamyogibntawmcovob peb yam tshwj xeeb uas xav tau imdaim ntawv cog lusxeemngonpaub tseebgra uades.
