Inothi lochwepheshe elibalulekile: Lona umbhalo wokufundisa ongowomlando, hhayi incazelo yedizayini yamanje, ukubala okumile, ubufakazi bomthamo womthwalo noma imiyalelo yokukhiqiza nokuhlanganisa. Ukuklanywa kwezakhiwo zensimbi kufanele kufake izenzo zangempela, ukuxhumana, ukuzinza, ukukhathala, umlilo, ukugqwala kanye nazo zonke ezinye izimo ezifanele ngokuvumelana nemithethonqubo evumelekile nezindinganiso, nomthwalo wemfanelo womklami ogunyaziwe.
Ukuklanywa nokwakhiwa kwezakhiwo zensimbi akuyona ingxenye yesipho somphakathi samanje se-Savo Kusić. Ukugxila kokukhiqiza kwanamuhla kuhlanganisa amawindi okhuni, amafasitela okhuni-aluminium kanye neminyango yangokwezifiso.
Izakhiwo zensimbi zinesici esivamile ngoba ngokuvamile zenziwe ngensimbi egoqwe eshisayo. Ukujoyina kwenziwa ngokusebenzisa ama-rivets, izikulufu noma i-welding. Lokhu kuhlanganisa izakhiwo zensimbi zamabhuloho, izakhiwo, izimboni kanye nezimayini, ubunjiniyela bamanzi, izinsika, imibhoshongo, amathangi, ngomqondo obanzi kanye nama-cranes, ukwakhiwa kwemikhumbi, ama-boilers, njll. Ukugxila kwalezi zethulo ezilandelayo ukuphathwa kwemiqondo eyisisekelo.
Izinto
Izinto zokwakha eziyinhloko zokwakhiwa kwensimbi ziyiziphrofayili ezigoqiwe ezivela ensimbi yekhwalithi yokwakha S235, S275, S355, S420, S450. Kuye ngezinga, kunezinhlobo eziningana ezahlukene zensimbi yokwakha, lapho inombolo esesigabeni ngokuvamile ibonisa amandla ensimbi. Kunezimpawu zezinhlamvu eziningana, lapho kulokhu u-S umele insimbi yesakhiwo. Amafomu avame ukusetshenziswa yi-S, B (izinsimbi zikakhonkolo, ukuqinisa) kanye no-Y (insimbi yokucindezela).
Izisekelo ezigoqelwe zensimbi
Kukhona uhla olubanzi lwezisekelo zensimbi ezinephrofayili futhi ngayinye inenhloso yayo, izinzuzo kanye nokubi.
- U-amaphrofayili
- Amaphrofayili e-I anemilenze emincane (IPE, IPN)
- Amaphrofayili e-I anemilenze ebanzi (HEA, HEB, HEM, HD)
- Amaphrofayili/amabhokisi angenalutho (indilinga, isikwele, unxande)
- Amashidi
- Imikhiqizo ebandayo (etholwe ngokugoqa okubandayo umucu oyisicaba kanye nokusonta umucu oyisicaba)
Ngayinye kulawa maphrofayela ayahluka ngomumo, ubukhulu, inhloso, njll. Isibonelo, kunamaphrofayela angaphezu kuka-20 e-IPN ahlukene, ahluka ngobukhulu; amaphrofayili amakhulu angamelana kangcono nokugoqa (i-flexural kanye ne-lateral-torsional), ukuphambuka, njll.
Kunezigaba ezine zensimbi kuye ngokuthi zifinyelela iphuzu lokukhiqiza lapho ukucindezeleka kwanda, kungakhathaliseki ukuthi ukuhlaziywa kuyipulasitiki noma i-elastic, imuphi umthamo womthwalo wesigaba sesiphambano, njll lapho iklasi lokuqala lingcono kakhulu futhi lesine libi kakhulu. Okuningi mayelana nesakhiwo namandla ensimbi kungafundwa lapha.
Ukulinganisa kwamandla kagesi kanye namandla okuthwala kumthwalo ozinzile
Umthamo wokuthwala. Ubukhulu bezakhiwo zensimbi bunqunywa ukuze ukuguqulwa okubalulekile okuhlala njalo kungabandakanywa. Umthamo wokuthwala, ngakolunye uhlangothi, ezimweni eziningi awuqedwa nganoma iyiphi indlela lapho ukucindezeleka okuqhathaniswa okuphezulu kufinyelela iphuzu lokukhiqiza - khona-ke ukuguqulwa kukhula ngokushesha kakhulu kunokucindezeleka. Ngensimbi yesakhiwo, ukuncika okufanayo nalapho ukuhoxa kungathathwa njengomkhawulo womthetho ka-Hooke wezimo zengcindezi evamile. Esimeni se-homogeneous stress states, ezilingana kuzo zonke izindawo, azikho izinguquko ezenzekayo lapho umkhawulo wokulinganisa weqiwe, ngaphandle kokuthi ukonakala okuphelele kukhula ngokushesha kunokucindezeleka.
Ukulinganisa kwengcindezi ngesikhathi sokugoba. Esimeni sokugoba kwe-beam, ukusabalalisa kwengcindezi ye-rectilinear ngokuya nge-Navier hypothesis kuyasebenza, kuze kube yilapho ukucindezeleka konqenqema σ=M/W kungedluli umkhawulo wokulinganisa. Izandiso ze-longitudinal ε = ε(σ). Lokhu kuyiqiniso okungenani ngokugoba okuncane. Izingcindezi eziphakeme kunokucindezeleka okulinganiselwe zingakhula kancane kancane kunezandiso ε. Emkhiwaneni. 1 ibonisa ukusatshalaliswa kwengcindezi egobekayo kumdwebo onikeziwe wokusebenza kanye namavelu ahlukahlukene onqenqema lokunwetshwa. Indawo yokulinganisa (emakwe ngombuthano kuyo yonke imigqa kagesi) iba yincane futhi ibe ncane ngokunwetshwa konqenqema okwandayo. I-voltage yonqenqema iqala ngokukhawulwa ngu-σF. Kuphela ngemva kokuguqulwa okuphawulekayo lapho ukucindezeleka okukhulu kukhuphuka ngaphezu kwe-σF, ukuze umthelela wokuqiniswa kwensimbi yesakhiwo ubonakale (icala 5).
Fig. 1 - Ukulinganisa i-voltage egobisayo
Ukulingana kweziqongo zokucindezeleka. Ukusatshalaliswa kokucindezelwa kwe-longitudinal kuso sonke isigaba phakathi nembobo ebhodweni elilodwa elicijile cishe kuhambisana nomugqa 2 kufig. 2. Ukuphakama kwamandla kagesi okungu-σmax kuncike esilinganisweni sika-d/b. Ikakhulukazi izungeze u-σmax = 2-3 σm, lapho u-σm = S/FM isho inani elimaphakathi lengcindezi yokuqina esigabeni esenziwe buthaka imbobo ku-FM. Sl. 2 isebenza kuze kube yilapho isimo se-voltage sidlula umkhawulo ongu-P. Emithwalweni ephakeme, ukuze kuzuzwe ukunwetshwa okuthile, ama-voltage aphansi kunomthetho womugqa oqondile adingeka kuphela eduze nomgodi. Emaphuzwini agcizelelwe kakhulu, izingcindezi ngeke zisakhula ngokulingana no-S, kodwa kunalokho kuzohamba kancane. Emngceleni, cishe ukusabalalisa okufanayo okufanayo kwezingcindezi zelongitudinal σm = σf kuzotholakala kuso sonke isigaba 2-2. Izingcindezi zokugunda nokuguquguquka azinakwa. Izehlakalo zokulinganisa ukucindezeleka phakathi nokwenyuka kancane kwamandla ka-S entongeni kufakazela ukuthi indlela evamile yezakhiwo zensimbi ngaphansi komphumela womthwalo omile ilungile, ukungazinaki iziqongo zokucindezeleka phakathi nobukhulu kanye nokuqhathanisa kuphela ukucindezeleka okumaphakathi σm=S/Fm esigabeni esibuthakathaka Fm nevelu elivumelekile.
Fig. 2
Inqubo yokulinganisa ngokomthamo wokulayisha
Njengoba umthwalo ukhula, ukulinganisa kwe-voltage kwenzeka esigabeni. Ngokwenza kanjalo, ukucindezeleka kuhlanganiswe kabusha kusukela ezingxenyeni ezigcizelelwe kakhulu zesigaba kuya kwezicindezelwe kancane. Uma nje ukuguqulwa akukukhulu kangangokuthi kufanele kucatshangelwe lapho kusetha izimo zokulinganisa, le nqubo ayikwazi ukuguqula noma yini ngobukhulu bethonya le-S, M, njll. ngezakhiwo ezinqunywe ngokwezibalo.
Ukusekela okuqhubekayo nohlaka: ngaphansi kokucatshangwa komthetho ka-Hooke, kutholakala ngokusekelwa okukodwa okuqhubekayo kwesigaba esingaguquki (isif.3) umugqa wesikhashana oboniswe ngaphansi kuka-a. Izingcindezi zokugoba zilingana nezikhathi zokugoba M. Uma yomibili imithwalo ikhuphuka ngokulinganayo, umkhawulo we-P uzoqala udlule ekusekelweni okuphakathi nendawo B. Umkhawulo wokuthwala ufinyelelwa lapho umzuzu wokukhawulela i-MDF ifinyelelwa ensimini futhi. Endabeni yenduku eboshwe ezinhlangothini zombili zesigaba esivumelanayo esingaguquki ngamandla agxilile (isig.4) ukulinganisa kwesikhashana kukhona kusukela ekuqaleni. Uma umkhawulo we-P weqiwe, alukho ushintsho ekusabalaliseni kwesikhashana. Ngokuphambene nalokho, esimweni somthwalo esabalaliswa ngokulinganayo (Fig.5) ukulingana kwezikhathi kuholela ekuncishisweni kwesikhathi sokumpintsha -2/3 Mmayelana -1/2 Mo.
Sl.4
Sl.3njll.5, ngokulandelanayo: izikhathi zokugoba: a) ngaphambili, b) khawula isimo ngemva kokuhlanganisa kabusha amandla; a) ngaphambili, b) ngemva kokulinganisa umfutho
Ukwakhiwa kwe-Lattice: ngama-trusses angaphakathi angenakulinganiswa, kukhona ukuncika okufanayo njengokwakhiwa kohlaka. Izingcindezi zesibili, ezihambisana namanodi aqinile ekugobeni, zinganakwa ekulinganisweni kokuqala lapho kuhlolwa umthamo womthwalo. Izingxenye ezenziwe ngepulasitiki zisebenza ngendlela efanayo namalunga, ukuze isenzo esimile sebhande elingaphansi komthwalo omkhulu esakwazi ukulithwala sisondele kulelo truss elikahle elinamalunga kumanodi. Endabeni yokwakha enemithwalo ephindaphindiwe, lapho izimo zamandla okukhathala kufanele zicatshangelwe, ngakho-ke kukhona ukungabaza okukhulu ngokumelene nokulingana kwamandla ngesikhathi sokulinganisa. Ngokuphambene nalokho, kubalulekile ukuphetha ngomthelela wokususwa kwezisekelo. Njengoba amandla okusebenza ezakhi zomuntu ngamunye zesakhiwo ancike kuphela emikhawulweni yokucindezeleka, futhi hhayi kusayizi wokuguqulwa okuphelele, ukufuduka kwezisekelo akunawo umthelela kumthamo wokuthwala.
Umthwalo oshintshanayo: ukuqagela kwekesi lomthwalo ongashintshi akuvamile ukubonwa. Ngamagida ebhuloho, kunezifunda zomthwalo oguquguqukayo. Ukucabangela mayelana namandla nokusabalalisa ukucindezeleka ezakhini zesakhiwo ngasinye, ezenza kube lula, zivamile emsebenzini osebenzayo nezakhiwo zensimbi, ngokusho kwangaphambilini, zilungisiwe ngaphansi kwezimo ezivamile. Lokhu kuyiqiniso ikakhulukazi ngokunganaki ukuphakama kwamandla kagesi wendawo. Ngeke kunconywe ukusebenzisa indlela yokulinganisa ngokuya ngomthamo wokulayisha ngaphansi kokulayisha (okuguquguqukayo) kokukhathala. Ngakho-ke, inqubo yokulinganisa ngokomthamo wokulayisha ikhawulelwe esimweni semithwalo emile kakhulu, ikakhulukazi ezakhiweni embonini yokwakha. Kwezinye izimo, lapho ukunakekelwa kufanele kukhokhwe ekubukeni kokukhathala, ukuguqulwa okuphawulekayo kuyodingeka kukhishwe futhi inkolelo-mbono yokunwebeka ithathwe njengesisekelo. Ngokwenza kanjalo, umuntu kufanele alwele ibanga elikhulu ngokwanele ukusuka endaweni yokukhiqiza. Ukuqina kwensimbi yokwakha bese kunikeza ukuvikeleka okwengeziwe.
Ukushintshana kwengcindezi
Ukwelula okubandayo nokuguga: Kufig. 6 ulayini wokukhulisa ingcindezi wenduku eyindilinga, evezwe ekucindezelekeni okushintshanayo nokucindezelayo, kusetshenziswe. Izinqubo zomthwalo ngamunye zimakwa ngezinombolo ngokuya ngokuhleleka kwazo. Ukwenyuswa kwe-elastic okubuyayo lapho kukhishwa futhi kwenzeka ngemva kokunwebeka okukhulu ngokulingana nezingcindezi. Lapho ushintsha uphawu lwe-voltage, umkhawulo we-P ucishe unyamalale ngokuphelele. Ngakho-ke, izakhiwo ezinwebekayo zensimbi yokwakha ezidwetshwe esimweni esibandayo azivumelani namanani okuqala. Ngokuya ngokucubungula kwangaphambilini, umehluko omkhulu ungaboniswa.
Fig. 6
Kahambisana nalokho kuza nezimpawu eziningi zokuguga. Leli gama lihlanganisa zonke izinguquko ezakhiweni ezenzeka ngokuhamba kwesikhathi ngaphandle komthelela wangaphandle. Ukwelula ukuguga kungabonwa ngemuva kokuguqulwa okungapheli ngokunwebeka okubandayo. Uma ama-specimens okuhlola anwetshiwe ashiywa isikhathi esithile ngaphandle komthwalo ekamelweni lokushisa, amandla aqinile futhi, ngokwezinga elincane, amandla okudabula akhuphuka ngaphezu kwevelu yoqobo, kuyilapho ubude ngesikhathi sekhefu kuncipha (Fig. 7). Inqubo yokuguga ithatha izinsuku, kodwa yehliselwa emahoreni ambalwa noma imizuzu nje, uma insimbi yesakhiwo ishiselwa cishe ibe ngu-300 oC. Kufanele futhi kukhulunywe ukuthi ukuguga okunwebekayo kwenzeka kanyekanye nokuzelula, uma lokhu kwenzeka ngesikhathi sezulu. 200 – 400 oC, i.e. endaweni yokukhanya okuluhlaza okwesibhakabhaka.
Fig. 7 - a) umugqa wokunweba wenduku elayishwe kabili; b) umugqa wokunweba wenduku oweluliwe esimweni esibandayo
Isenzo esilandelayo kanye ne-hysteresis: Entweni enwebeka ngokuphelele, kukhona ukuncika okulinganayo phakathi kwengcindezi kanye nesimo sokuguquguquka, ukuze ukucindezeleka okuthile kuhlale kuhambisana nokuguquguquka okufanayo futhi ngokuphambene nalokho. Ngomthetho onikeziwe we-elasticity, ukuguqulwa akuxhomeki esikhathini esidlule kusukela kusetshenziswe umthwalo, futhi hhayi endleleni lapho umthwalo usetshenziswa khona. Ukuphambuka ekuziphatheni okunwebekayo kuphela kungachazwa ngamadigri amabili okulinganisa: endaweni enwebekayo kukhona ukuchezuka okuncane; zinganakwa ekulinganisweni kokuqala. Zinganqunywa ngezilinganiso ezinembile, ikakhulukazi uma uqhathanisa ukucindezeleka eduze nomkhawulo wokunwebeka. Okungukuthi, i-dilatation akuyona nje umsebenzi we-voltage, kodwa ngomjikelezo womthwalo ovaliwe kanye ne-voltage efanayo, ihlale incane kancane ngesikhathi sokuthulula kunesikhathi sokulayisha. Ukuchezuka ku-elasticity ephelele, isb. umehluko phakathi kokwandiswa okuhambisanayo ekucindezelekeni okufanayo kubizwa ngokuthi i-elastic hysteresis. Uma umjikelezo womthwalo uphindaphindwa kaningi, lokhu kutholakala ngama-voltage angephezulu kakhulu - iluphu evaliwe ye-hysteresis noma i-damping. Sl. 8 ibonisa amalophu anciphayo amanani ahlukahlukene wokulayisha we-AC. Ububanzi bama-loops bukhula kakhulu ngokuphakama kwe-voltage. Indawo ye-loop ilingana nomsebenzi wokuguqula, olahlekayo kumjikelezo ngamunye futhi uguqulelwe ekushiseni. Futhi, ukuguqulwa akuguquki hhayi kuphela ngokuphakama kwe-voltage kodwa futhi nesikhathi, kuncike esivinini kanye nendlela yokulayisha. Ingxenye ye-deformation, encike esikhathini, ibizwa ngokuthi umphumela. I-Hysteresis kanye nomphumela kwenzeka ngesikhathi esisodwa. Njengomthetho, azikho ukubaluleka okungokoqobo kwalezo zinhlobo zensimbi yokwakha ezenzeka ezakhiweni zensimbi emazingeni okushisa asekamelweni.
Sl. 8
Inothi Lohlelo Lokusebenza: Izimpawu zezinto zomlando, okucatshangwayo, imidwebo nezinqubo ezisembhalweni akufanele zisetshenziswe esikhundleni samazinga amanje, izici ezithile zomkhiqizo, imodeli yokubala kanye nokuqinisekisa kochwepheshe kwesakhiwo sonke.