Pwopriyete mekanik
MoST FASTENERaplikasyon yoyofètasipò oswatransmli konsamfòmnandeyò aplikeloanons.Sithe fòsnantheFastenerse thesèl enkyetid,therese nòmalman nonbezwenagadedweyondkabònasye.Plis pase
90%nantout Fasteneryomadenankabònasye.Nanjeneral,konsideringthepri nankrimaterials,ki pa FERROUSta dwedwekonsideredsèlman lèaaplikasyon espesyalobligatwa.
Fòs rupture
Lamost lajman asosyemechanical pwopriyete ki asosye ak kanpeard Fastener Threaded se fòs rupture.Fòs rupturese themaksmumtansyon-aplikeloanonstheFastenerkapabsipò prioraoswa kowensideavèkli yoka zo kase(gadefigi1).
Chaj rupture yon Fastener ka withstakse dekourajeminedpa thepoumula
P = StxAs Example(gadeapendispouStakAsvalè)
kote 3/4-10x7”SAEJ429Klas5HCS
P = tensile loanons(lb., N) St=120,000psi
St=fòs rupture(psi,MPa) As=0.3340sq.nan
As= tensile zòn estrès (sq.in, sq. mm) P =120,000psi x0.3340sq.nan
P =40,080lb.
Pouthse relasyon,asiyifikatif konsiderasyonmust dwebayathedefinisyonnantheestrès rupturezòn,As. WhenaestandathliFastenerechwe nanpitensisou,it typically fracturesthki grajthethliportion(thse characteristically li nan smallest zòn).For thse reasou,the tensile zòn estrès se kalsulated
thki grajyonempirikal poumulaki enplikethenonminal diametènantheFastenerakthethlianplasman.Tablo ki deklarethse zòn nanyobaypouyounantheapendis.
Chaj Prèv
Figi1 Tensile Estrès-SouchDyagram
Laprèvloanonsreprezante thefòs ki ka itilizeranjepousètenestandaFastener.Pa definisyon,theprèv loanonsse yonaplikerupture loanonsthnan theFastenermust sipò san yo pa permanent deformatyon.Nanlòt
words, the bolt returns pouli yooriginal shape souce the loanonsse removed.
Figure 1maladustrates yon typical estrès-souchrelatisoushipofa bokòm yon tensionloanonsse yonppmantid. The asye posede yon sèten yonmount nan elastisite kòm li se detireed. SilachajseremovedaklaFastenersetoujou konprannhnanthe elastik range, the fastener ap toujou returnali yooriginal shape. Si,honouver, the loanonsappkoz mantitheFasteneradwepote sot pase li yoyieldpwen,li kounye aantretheranje plastik.Isit la,theasye se pa gen okenn ankòkapabreturnaori li yoginal fòmsitheloanonsse removed.Layieldfòsse thepwen nan ki pou chakmanentelongasyonrive.Sinouwta dwekontinyeaaplikeachaj,noutariveapwennanmaksmum
estrès li te ye tankou ulti lammanje fòs rupture.Pase pwen sa a,laFastenerkontinuesa"Kou"akpwolonje
1
further akyon reductionnanestrès.Additisoual stretchingpralultimately cause the fastener abreaknan the pwen rupture.
CheaFòs
Cheafòsse definikòmthemaksmumloanonsthnan kapabdwesipòteprioraka zo kase,Kilèaplikenan yon ang dwatatheFastener laaks.Aloanonsrivenanyon sèltransverseavyonse li te yekòmsèltaye.
DoubletayeseachajaplikenandeavyonkotelaFastenerte kapabdwekoupe an twa moso.Figi 2 se
yonexamplenandoubtaye.
Poumost estandathliFastener,tayefòsis pa yonspesifikasyonificatisoumenmthoughthefastenermay kommsèlman itilizenantayeaplikasyon yo.While tayetèsnanavègrive se yonbyen estandapwosedi ki mande pou yon aparèy tès taye sèl, te lastingtekniknanthliFastenerse pa tankoubyen
fèt.Mopwosedi STitilizeadoubtayeaparèy,men varyasyonnantheaparèy tèsdesenkòzyon lajègayenanmfasilitetayefòs.
Poudetèmine the shzòrèy strengthofthe material, the total cross-sectisoual yonrea nan plan an taye se mwenmportant.Poutayeavyonthki grajthethli,noute kapabitilizetheekivalan estrès rupturezòn nan(Kòm).
Figi 2 montre de posiblite forlaapliketayechaj.Younhaslatayeavyonkorespondanak the threadedportionofthe bolt.Since shzòrèy strengthsedirèkteman ki gen rapòathe net sectisouyon zòn, kòmmaller
zòn pral result nanlowerbolt shzòrèy strength. Poutake full yondvantage ofstrengthproperties, the prefere konsepsyontadweapozisyonlaplenshankkònanlaavyon tayekòmilistreavèklajwentisouladwa.
Figi2CheaAvyonnanaBoltedJoint
Whennontayefòsse bay yopoukommsoukabònasyeavèkditelevea40HRC,60%nantheir ultimse fòs rupture souvan itilize yon fwa yo bay yon kostimable faktè sekirite.Sa ata dwesèlmandweitilizekòman estimatisou.
FatigFòs
AFastenersibiarepetecyklike loAjouteka toudenkou aksanzatann kraze,menmsitheloAjouteyo
byenbelow the strengthofthe material.The fastener echwe nanfatigue. The fatigue strengthse the maximum estrèsaFastenerkapabkenbe tèt akpouaespesifyenumbernanrepetesikanvanali yoechèk.
Torsional fòs
Fòs torsionalse yonloanonsanjeneral eksprimenantermsnantorque,nan kitheFastenerechwe pa ke yo te tresekoupesou aks li yo.Frapanvisak priz mete vismandeatotès rsional.
Lòt pwopriyete mekanik
Dite
Dite se yonmeasure nan yonmkapasite aterial pou rezistefwotmanakendentasyon.Pou asye kabòn, Brinell akRockwell ditetèskapabdweitilizeaestimmanjefòs rupturepwopriyetenantheFastener.
Ductility
2
Ductility se yonmEASureofthe degreeofplastikdeformationthnanhkòmbeensustainednan fraktiure.Nanother words, li se the abilityofa material todeformbeforeli fraktireures.A material thnan experiencesvery ti krasor
nonplastikdeformatyonsouka zo kasesekonsiderebrittle. Arezonabendikasyonnan duktilite Fastener la
se the rapòofs li yopekifyeminimumsedestrengthathe minimumtensile strength. The lower thse rapò the moreductile the fastener pralbe.
Rezistans
Rezistanssedefinikòmamaterial lakapasiteaabsòbeimpakoswachòkchaje. Mwenmpakfòsseverite
se raman yon spesifikasyon requirement.Anplisdivès kaliteendistri ayewospasyalFastener,ASTMA320
Specificationfor toutoy Steel BoltingMateryèl forLow-TemperatureSèvisseyon sèlnanlakèk espesifikasyon ki mande pou mwenmpaktestingonsètengrades.
