Lub zog ntawm kev sib txhuam yog lub cev muaj zog uas tiv thaiv kev txav ntawm lub cev. Nws tshwm sim, raws li txoj cai, thaum lub cev txav mus rau hauv cov khoom, kua thiab gaseous teeb meem. Ntau hom kev sib txhuam rog ua lub luag haujlwm tseem ceeb hauv tib neeg lub neej, vim tias lawv tiv thaiv kev nce siab hauv lub cev.
Kev faib tawm ntawm kev sib txhuam rog
Hauv rooj plaub dav dav, txhua hom kev sib txhuam quab yuam tau piav qhia los ntawm peb hom: kev sib txhuam quab yuam ntawm zawv zawg, dov thiab so. Qhov thib ib yog static, lwm qhov yog dynamic. Kev sib txhuam thaum so tiv thaiv lub cev los ntawm kev pib txav mus los, tig, thaum zawv zawg, kev sib txhuam tshwm sim thaum lub cev rub tawm ntawm lwm lub cev thaum nws txav mus. Rolling kev sib txhuam tshwm sim thaum ib puag ncig khoom txav. Cia peb ua piv txwv. Ib qho piv txwv zoo ntawm hom (dov kev sib txhuam quab yuam) yog kev txav ntawm lub tsheb log ntawm asph alt.
Qhov xwm txheej ntawm kev sib txhuam rog yog qhov muaj qhov tsis zoo ntawm microscopic ntawm qhov sib txhuam ntawm ob lub cev. Vim li no, lub resulting quab yuam ua rauib qho khoom txav los yog pib txav mus los, muaj qhov sib npaug ntawm lub zog ntawm cov tshuaj tiv thaiv ib txwm muaj ntawm kev txhawb nqa N, uas yog coj mus rau qhov chaw ntawm lub cev sib txuas, thiab ntawm kev sib txhuam quab yuam F. Qhov kawg yog qhia thaum uas tig mus rau lub cev. kev sib cuag saum npoo thiab yog qhov sib txawv ntawm qhov txav ntawm lub cev.
Kev sib txhuam ntawm ob qho khoom
Thaum xav txog qhov teeb meem ntawm ntau hom kev sib txhuam, cov qauv hauv qab no tau soj ntsuam rau ob lub cev:
- Kev sib txhuam quab yuam yog coj mus rau qhov sib npaug rau qhov chaw txhawb nqa.
- Cov coefficient ntawm kev sib txhuam yog nyob ntawm qhov xwm ntawm qhov chaw sib cuag, nrog rau lawv qhov xwm txheej.
- Kev sib txhuam siab tshaj plaws yog nyob rau hauv kev faib ua feem ncaj qha rau lub zog ib txwm muaj lossis kev txhawb nqa cov tshuaj tiv thaiv uas ua rau ntawm qhov chaw sib cuag.
- Rau tib lub cev, kev sib txhuam quab yuam ntau dua ua ntej lub cev pib txav thiab tom qab ntawd txo qis thaum lub cev pib txav.
- Cov coefficient ntawm kev sib txhuam tsis nyob ntawm qhov chaw sib cuag, thiab nws xyaum tsis nyob ntawm qhov zawv zawg ceev.
Laws
Summarizing cov khoom siv sim ntawm txoj cai ntawm kev txav, peb tau tsim cov cai hauv qab no hais txog kev sib txhuam:
- Qhov kev tiv thaiv zawv zawg ntawm ob lub cev yog proportional rau lub zog ib txwm ua ntawm lawv.
- Kev tiv thaiv kev txav ntawm lub cev rub tawm tsis yog nyob ntawm thaj chaw sib cuag ntawm lawv.
Txhawm rau ua kom pom txoj cai thib ob, peb tuaj yeem muab cov piv txwv hauv qab no: yog tias koj siv lub thaiv thiab txav nws los ntawm zawv zawg rau saum npoo, ces lub zog tsim nyog rau kev txav mus los.yuav zoo ib yam thaum lub thaiv nyob rau saum npoo nrog nws sab ntev, thiab thaum nws sawv nrog nws kawg.
Cov kev cai lij choj hais txog ntau hom kev sib txhuam quab yuam hauv physics tau pom thaum kawg ntawm lub xyoo pua 15th los ntawm Leonard da Vinci. Tom qab ntawd lawv tau hnov qab ntev, thiab tsuas yog xyoo 1699 lawv tau rov tshawb pom los ntawm Fab Kis tus kws tshaj lij Amonton. Txij thaum ntawd los, cov kev cai ntawm kev sib txhuam dais nws lub npe.
Vim li cas kev sib txhuam quab yuam ntau dua li zawv zawg thaum so?
Thaum xav txog ntau hom kev sib txhuam quab yuam (so thiab zawv zawg), nws yuav tsum tau muab sau tseg tias qhov kev sib txhuam zoo li qub yog ib txwm tsawg dua los yog sib npaug rau cov khoom ntawm qhov sib txhuam coefficient thiab cov tshuaj tiv thaiv ntawm kev txhawb nqa. Cov coefficient ntawm kev sib txhuam yog txiav txim siab sim rau cov ntaub ntawv rub thiab nkag mus rau hauv cov rooj tsim nyog.
Dynamic quab yuam yog suav nrog tib yam li lub zog zoo li qub. Tsuas yog nyob rau hauv rooj plaub no, tus coefficient ntawm kev sib txhuam yog siv tshwj xeeb rau zawv zawg. Kev sib txhuam coefficient feem ntau txhais los ntawm Greek tsab ntawv Μ (mu). Yog li, cov qauv dav dav rau ob qho kev sib txhuam quab yuam yog: Ftr=ΜN, qhov twg N yog qhov kev txhawb nqa quab yuam.
Qhov sib txawv ntawm cov hom kev sib txhuam no tsis tau tsim muaj tseeb. Txawm li cas los xij, feem ntau cov kws tshawb fawb ntseeg tias qhov kev sib txhuam zoo li qub yog ntau dua li qhov zawv zawg, vim tias thaum lub cev nyob ntawm qhov sib txheeb ze rau qee lub sijhawm, ionic bonds lossis microfusions ntawm tus kheej cov ntsiab lus ntawm qhov chaw tuaj yeem tsim ntawm lawv qhov chaw. Cov xwm txheej no ua rau muaj kev nce hauv staticqhov taw qhia.
Ib qho piv txwv ntawm ntau hom kev sib txhuam quab yuam thiab lawv qhov tshwm sim yog lub piston hauv lub tog raj kheej ntawm lub cav tsheb, uas yog "soldered" rau lub tog raj kheej yog tias lub cav tsis ua haujlwm ntev.
Kab rov tav zawv zawg lub cev
Cia peb tau qhov sib npaug ntawm kev txav mus rau lub cev uas, nyob rau hauv qhov kev txiav txim ntawm sab nraud quab yuam Fin, pib txav mus rau saum npoo los ntawm zawv zawg. Hauv qhov no, lub zog hauv qab no ua rau lub cev:
- Fv - sab nraud quab yuam;
- Ftr - kev sib txhuam quab yuam uas yog rov qab coj mus rau lub zog Fv;
- N yog lub zog tawm tsam ntawm kev txhawb nqa, uas yog sib npaug ntawm tus nqi tiag tiag rau qhov hnyav ntawm lub cev P thiab raug coj mus rau saum npoo, uas yog, ntawm lub kaum sab xis rau nws.
Kev ua raws li cov lus qhia ntawm txhua lub zog, peb sau Newton txoj cai thib ob rau rooj plaub ntawm tsab ntawv tsa suab no: Fv - Ftr=ma, qhov twg m - lub cev loj, a - acceleration ntawm txav. Paub tias Ftr=ΜN, N=P=mg, qhov twg g yog lub caij nplooj zeeg dawb acceleration, peb tau txais: Fv – Μmg=mua. Thaum twg, qhia qhov nrawm uas lub cev zawv zawg txav, peb tau txais: a=F hauv / m – Μg.
Kev txav ntawm lub cev nruj hauv cov kua
Thaum txiav txim siab seb hom kev sib txhuam muaj dab tsi, ib tus yuav tsum hais txog qhov tshwm sim tseem ceeb hauv physics, uas yog cov lus piav qhia ntawm lub cev zoo li cas txav hauv cov kua. Hauv qhov no, peb tab tom tham txog kev sib txhuam aerodynamic, uas yog txiav txim siab nyob ntawm qhov ceev ntawm lub cev hauv cov kua dej. Muaj ob hom kev txav:
- Thaumib lub cev txhav txav ntawm qhov ceev, ib tug hais ntawm laminar motion. Kev sib txhuam quab yuam hauv laminar txav yog proportional rau qhov tshaj tawm. Ib qho piv txwv yog Stokes txoj cai rau lub cev kheej kheej.
- Thaum lub zog ntawm lub cev hauv cov kua dej tshwm sim ntawm qhov nrawm dua li qhov pib ntawm tus nqi, ces cov vortices los ntawm cov kua dej pib tshwm nyob ib ncig ntawm lub cev. Cov vortices no tsim ib qho ntxiv quab yuam uas cuam tshuam kev txav mus los, thiab vim li ntawd, kev sib txhuam quab yuam yog proportional rau square ntawm ceev.
Txoj kev sib txhuam quab yuam
Thaum tham txog hom kev sib txhuam quab yuam, nws yog kev cai hu rau kev sib txhuam quab yuam thib peb. Nws manifests nws tus kheej thaum lub cev yob hla ib qho chaw thiab deformation ntawm lub cev no thiab nto nws tus kheej tshwm sim. Uas yog, nyob rau hauv cov ntaub ntawv ntawm ib tug kiag li uas tsis yog-deformable lub cev thiab nto, tsis muaj ntsiab lus nyob rau hauv tham txog lub zog ntawm dov kev sib txhuam. Cia peb saib ntxiv.
Lub tswvyim ntawm dov kev sib txhuam coefficient zoo ib yam li qhov zawv zawg. Txij li thaum tsis muaj kev swb ntawm qhov chaw ntawm lub cev thaum dov, lub coefficient ntawm dov kev sib txhuam yog tsawg dua rau zawv zawg.
Qhov tseem ceeb uas cuam tshuam rau coefficient yog hysteresis ntawm txhua yam zog rau hom dov kev sib txhuam quab yuam. Hauv particular, lub log, nyob ntawm seb cov khoom siv los ntawm qhov uas nws tau ua, nrog rau cov khoom thauj nws nqa, yog elastically deformed thaum lub sij hawm txav. Rov ua dua cov voj voog ntawm elastic deformation ua rau kev hloov ntawm ib feem ntawm lub tshuab hluav taws xob rau hauv thermal zog. Ntxiv rau, vimkev puas tsuaj, kev sib cuag ntawm lub log thiab qhov chaw twb muaj qee qhov chaw sib cuag.
rolling kev sib txhuam quab yuam formula
Yog peb siv cov lus qhia rau lub sijhawm ntawm lub zog uas tig lub log, ces peb tuaj yeem tau txais tias lub zog sib txhuam yog Ftr.k.=Μ k N / R, ntawm no N yog cov tshuaj tiv thaiv ntawm kev txhawb nqa, R yog lub vojvoog ntawm lub log, Μк – dov kev sib txhuam coefficient. Yog li, lub dov kev sib txhuam quab yuam yog inversely proportional rau lub vojvoog, uas piav qhia qhov zoo ntawm cov log loj dua cov me.
Qhov sib txawv ntawm qhov sib txawv ntawm qhov quab yuam no rau lub vojvoog ntawm lub log qhia tias nyob rau hauv rooj plaub ntawm ob lub log ntawm lub vojvoog sib txawv uas muaj tib lub zog thiab ua los ntawm cov khoom siv tib yam, lub log nrog lub vojvoog loj dua yooj yim dua. khob.
Rolling ratio
Ua raws li cov qauv rau hom kev sib txhuam quab yuam, peb tau txais tias cov coefficient ntawm dov kev sib txhuam Μ kmuaj qhov ntev ntawm qhov ntev. Nws tsuas yog nyob ntawm qhov xwm txheej ntawm lub cev tiv tauj. Tus nqi, uas yog txiav txim los ntawm qhov piv ntawm dov kev sib txhuam coefficient rau lub vojvoog, yog hu ua rolling coefficient, uas yog, Ck=Μk / R yog qhov tsis muaj nuj nqis.
Cov dov coefficient Ck yog tsawg dua qhov coefficient ntawm zawv zawg kev sib txhuam Μtr. Yog li ntawd, thaum teb cov lus nug ntawm hom kev sib txhuam quab yuam yog qhov tsawg tshaj plaws, peb tuaj yeem hu rau lub zog sib txhuam kom ruaj ntseg. Ua tsaug rau qhov tseeb, qhov kev tsim ntawm lub log yog suav tias yog ib kauj ruam tseem ceeb hauv kev ua haujlwm thev naus laus zis.humanity.
Qhov piv piv yog qhov tshwj xeeb thiab nyob ntawm cov hauv qab no:
- hardness ntawm lub log thiab nto (qhov me dua qhov deformation ntawm lub cev uas tshwm sim thaum lub zog txav, qhov qis dua qhov coefficient ntawm dov);
- log vojvoog;
- hnyav uas ua rau ntawm lub log;
- hu rau thaj chaw thiab nws cov duab;
- viscosity hauv thaj tsam ntawm kev sib cuag ntawm lub log thiab qhov chaw;
- lub cev kub
