Koj puas tuaj yeem paub qhov txawv ntawm cov ntsiab lus thiab qhov sib txawv ntawm lub zog sab hauv, kev ntxhov siab, thiab kev nyuaj siab? Los saib tag nrho hnub no.
1. Lub tswv yim ntawm lub zog sab hauv
1. Kev txhais
Internal quab yuam yog hais txog kev sib cuam tshuam quab yuam (ntxiv lub zog sab hauv) ntawm qhov chaw nyob ib sab hauv ib yam khoom los ntawm kev quab yuam sab nraud. Lub zog quab yuam ntawm tus pas nrig los ntawm lub ntiaj teb sab nraud yog hu ua lub zog sab nraud.
Txhua yam khoom yog tsim los ntawm ntau qhov tsis txaus ntseeg, muaj kev sib cuam tshuam ntawm ob qhov sib txuas hauv cov khoom, thiab qhov loj ntawm lub zog muaj feem cuam tshuam rau qhov chaw txheeb ze ntawm cov khoom. Thaum ib yam khoom raug rau sab nraud quab yuam, cov khoom deforms, tus txheeb ze txoj hauj lwm ntawm nws cov ntaub ntawv sab hauv hloov, thiab kev sib cuam tshuam quab yuam ntawm lawv hloov raws li. Peb hu rau qhov kev hloov ntawm lub zog uas tsim los ntawm sab nraud quab yuam ntxiv rau sab hauv, lossis lub zog sab hauv luv luv.
2. Kev suav cov txheej txheem ntawm lub zog sab hauv-section method
Obviously, lub zog sab hauv yog nyob rau hauv cov khoom. Yog tias koj xav daws qhov quab yuam sab hauv, koj yuav tsum nthuav tawm lub zog sab hauv. Nyob rau hauv txoj kev no, peb siv txoj kev hla ntu los daws qhov cross-sectional txoj haujlwm ntawm lub zog sab hauv raws li qhov xav tau. Hypothetically txiav cov seem, tus thawj tswv cuab yog sib npaug, thiab ib feem tom qab txiav kuj sib npaug, uas yog, ib feem ntawm ob sab ntawm seem yog nyob rau hauv ib tug sib npaug xeev nyob rau hauv qhov kev txiav txim ntawm sab nraud quab yuam thiab sab hauv quab yuam ntawm seem. Yog li ntawd, koj tuaj yeem coj ib sab ntawm ntu, kawm txog nws cov xwm txheej sib npaug, tsim kom muaj kev sib npaug sib npaug, thiab daws qhov kev quab yuam sab hauv ntawm ntu. Cov kauj ruam tshwj xeeb los daws qhov seem yog raws li hauv qab no.
Hypothetical txiav: Nyob rau ntawm qhov chaw hla qhov chaw sab hauv yog nrhiav (feem ntau yog hla ntu), tus pas nrig yog xav txog muab faib ua ob los ntawm ntu ntu.
Hloov pauv: Ua ib feem ntawm qhov kev txiav txim siab, thiab cov txiaj ntsig ntawm qhov muab pov tseg ntawm qhov seem yog hloov los ntawm cov sib xyaw nrog cov quab yuam (yuav quab yuam lossis quab yuam ob peb) ua haujlwm ntawm ntu.
Balance: Tsim kom muaj qhov sib npaug sib npaug rau qhov seem, thiab suav qhov tsis paub lub zog sab hauv ntawm tus pas nrig ntawm qhov chaw txiav tawm raws li lub zog sab nraud uas paub txog ntawm nws (lub sijhawm no, lub zog sab hauv ntawm qhov txiav tawm yog ib qho sab nraud quab yuam rau qhov seem). Raws li qhov kev xav ntawm kev sib haum xeeb thiab kev txuas mus ntxiv, kev quab yuam tsis tu ncua yuav tsum tau muab faib ua ntu ntu tom qab txiav, thiab muaj cov zog sab hauv ntawm txhua qhov chaw ntawm ntu, tab sis tsuas muaj rau qhov sib npaug rau qhov kev quab yuam hauv qhov chaw, thiab peb daws tsis tau tag nrho lawv. Lub zog sab hauv ntawm txhua qhov chaw. Raws li qhov yooj yim ntawm kev quab yuam, peb ua kom yooj yim rau txhua qhov kev quab yuam ntawm lub zog sab hauv no mus rau qhov taw tes ntawm ntu, feem ntau mus rau qhov nruab nrab ntawm ntu, thiab tau txais lub ntsiab lus tseem ceeb thiab lub sijhawm tseem ceeb, raws li qhia hauv daim duab hauv qab no.
Siv lub centroid ntawm seem raws li lub hauv paus chiv keeb, tsim kom muaj ib tug Cartesian coordinate system raws li qhia nyob rau hauv daim duab, lub x-axis yog perpendicular rau tus ntoo khaub lig-section, uas yog, raws li axis ntawm tus pas nrig, thiab y-axis thiab z. - axis yog nyob rau hauv seem dav hlau. Decomposing tus thawj vector mus rau peb qhov kev sib koom axes tuaj yeem tau txais peb yam: lub zog axial raws x-axis, thiab lub zog shear raws li y-axis thiab z-axis.
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Decomposing lub sij hawm tseem ceeb nyob rau hauv peb txoj hauj lwm axes yields peb yam: torque raws lub x-axis, khoov lub sij hawm raws y-axis thiab z-axis.
Peb kuj hu rau cov khoom siv rau lub zog sab hauv, tab sis nws yuav tsum tau muab sau tseg tias rau lub ntsiab lus no yog lub zog tshwm sim lossis lub sijhawm ntawm lub zog sab hauv. Kev daws lub zog sab hauv ntawm lub bar tom qab yog nrhiav lub axial force, shear force, torque thiab dabtsi yog khoov lub sij hawm, vim hais tias cov internal rog sib haum mus rau lub hauv paus deformation ntawm lub bar: nro thiab compression deformation, shear deformation, torsional deformation, dabtsi yog khoov deformation.
2. Lub tswv yim ntawm kev ntxhov siab
Kev ntxhov siab yog qhov kev faib tawm ntawm lub zog sab hauv (kev ntxhov siab yog rau qee qhov "taw tes", thaum peb xav piav qhia txog qhov kev ntxhov siab ntawm qhov taw tes, peb yuav tsum taw qhia qhov chaw ntawm qhov taw tes no thiab kev taw qhia ntawm lub dav hlau hla qhov taw tes no), txhawm rau piav qhia txog qhov kev ntxhov siab ntawm qhov taw tes ntawm ntu, siv thaj chaw micro-DA nyob ib puag ncig ntawm qhov no, raws li pom hauv daim duab. Qhov tshwm sim quab yuam ntawm lub zog sab hauv ntawm qhov chaw micro-chaw yog DF. Txij li qhov chaw no me me txaus, peb xav tias lub zog sab hauv yog sib npaug, ces peb tuaj yeem tau txais qhov nruab nrab kev ntxhov siab, thiab tom qab ntawd coj qhov kev txwv ntawm qhov nruab nrab kev ntxhov siab kom tau txais tag nrho cov kev ntxhov siab los yog tag nrho cov kev ntxhov siab ntawm cov ntsiab lus no, cov kev taw qhia ntawm lub tag nrho kev ntxhov siab hloov nrog txoj hauj lwm ntawm qhov chaw xaiv. Obviously, tag nrho cov kev ntxhov siab yog vector, thiab kev sib raug zoo ntawm nws cov kev taw qhia thiab cov seem yog arbitrary. Tom qab ntawd peb decompose tag nrho cov kev ntxhov siab rau hauv ob lub ntsiab lus, ib qho yog hu ua kev ntxhov siab ib txwm nyob rau ntawm ntu, thiab lwm qhov yog hu ua shear stress tangent rau seem.
txhais tau tias kev ntxhov siab
tag nrho kev ntxhov siab (tag nrho kev ntxhov siab)
Tag nrho cov kev ntxhov siab yog decomposed rau hauv: qhov kev ntxhov siab perpendicular mus rau seem hu ua "kev ntxhov siab ib txwm", thiab kev ntxhov siab hauv seem hu ua "shear stress".
Chav tsev ntawm kev ntxhov siab: Pa, feem ntau siv: MPa, GPa.
3. Tshem tawm, deformation thiab lim
1. Kev khiav tawm
Txoj hauj lwm hloov ntawm ib qho taw tes hauv cov khoom ua ntej thiab tom qab deformation, qhov kev hloov pauv hauv cov khoom siv tshuab muaj cov kev hloov pauv thiab kev hloov pauv ntawm lub kaum sab xis. Raws li pom nyob rau hauv daim duab hauv qab no, ib tug concentrated quab yuam yog siv rau lub dawb kawg ntawm lub cantilever beam, thiab lub beam khoov thiab deforms. Yog tias peb tshuaj xyuas qhov kev hloov pauv ntawm qee ntu, xws li kev hloov pauv ntawm qhov kawg dawb, nws pom tseeb tias qhov chaw nruab nrab ntawm ntu yuav muaj kev hloov pauv mus rau hauv qab, uas ua rau muaj kev hloov pauv hloov pauv, thiab tib lub sijhawm, kev coj ua ib txwm muaj. seem yuav hloov, uas yog, seem yuav tig, uas ua rau ib tug angular txav. hloov chaw.
2. Deformation
Hloov qhov loj thiab cov duab ntawm ib yam khoom nyob rau hauv qhov kev txiav txim ntawm lub zog sab nraud.
3. Lim
Txhawm rau ntsuas qhov degree ntawm deformation ntawm qhov taw tes ntawm ib qho kev tivthaiv, qhov kev sib tw kuj yog rau qee qhov "point".
(1) Linear strain ( ntsuas qhov kev hloov pauv ntawm qhov loj ntawm qhov taw tes hauv ib qho khoom).
Raws li pom nyob rau hauv daim duab, peb tshuaj xyuas tej point A nyob rau hauv lub tivthaiv, thiab coj tej point B ze point A. Qhov ntev ntawm AB yog Dx. Cov tivthaiv deforms nyob rau hauv qhov kev txiav txim ntawm sab nraud quab yuam, thiab ob qho tib si ntsiab lus A thiab B raug hloov mus rau txoj haujlwm tshiab. Qhov kev ncua deb ntawm dhau los ua Dx ntxiv rau Ds, xav tias qhov deformation yog sib xws nyob rau hauv qhov ntau ntawm Dx, qhov nruab nrab linear strain tuaj yeem tau txais.
Peb siv qhov txwv ntawm cov qauv saum toj no kom tau cov kab mob ntawm point A
Rau cov teeb meem ntawm lub dav hlau, ib daim duab plaub me me tau pom hauv daim duab, thiab sab nraud quab yuam txoj kab ua ib daim duab plaub qhia los ntawm kab dotted (qhov loj me me hloov). Yog hais tias lub deformation yog sib xws nyob rau hauv qhov ntau ntawm Dx thiab Dy, muaj ib tug nruab nrab kab raws tus x thiab y cov lus qhia strain.
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Siv qhov txwv feem kom tau txais cov kab tawm hauv cov lus qhia x thiab y
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(2) Angular strain ( ntsuas qhov kev hloov pauv ntawm cov duab ntawm qhov taw tes hauv ib qho khoom) kuj hu ua shear strain lossis shear strain.
Txhais raws li qhov kev hloov ntawm lub kaum sab xis.
