Okubalulekile kokubala okumile
Ukhuni luyindalo yemvelo futhi, ngenxa yesakhiwo salo se-anatomical, luyimpahla yokwakha engalingani. Ingafaniswa nenqwaba yamashubhu, ahlelwe ngamanye ahambisanayo futhi annular azungeze umnyombo wesihlahla - izindandatho noma izindandatho zaminyaka yonke - lapho yonke indawo enezigaba ezihlukene ezihlukene kanye nogqinsi lwezindonga, okungukuthi ukhuni lwakuqala noluphuzile.
Ukuqina kokhuni kuncike ezimweni ukhuni olwakhula ngaphansi kwazo, futhi ngokwezinga elikhulu zithinteka amaphutha okhuni, ukungalungi ekuthuthukisweni, ubudala bezinkuni ngesikhathi sokugawulwa nokusetshenziswa futhi ikakhulukazi umswakama walo.
Inani lamandla elimaphakathi alihlukile nje kuphela esihlahleni ngasinye esisuka endaweni efanayo, kodwa nasesihlahleni esifanayo liyehla lisuka kokujiyile kakhulu liye ekugcineni elincanyana kakhulu. Esigabeni esiphambanayo, izindandatho zonyaka ezincane kunazo zonke ngaphansi kwegxolo zimelela ukhuni olungcono kakhulu nolukhuni. Isazi samahlathi singathonya izici zokhuni ngokwezinga elilinganiselwe, kuyilapho umsebenzisi engakwazi ukushintsha izici zamandla ngezindlela ezilula.
Amandla acindezelayo
Ingcindezi eya lapho kukhona imicu
Uma uhlola amasampula okuhlola, ngokuvamile ayisikwele esigabeni esiphambanayo, ukwehluleka kwenzeka ngenxa yokuthi izindonga zamaseli zemicu zisonteka zibe izimbotshana, lapho ukunwetshwa okuphambene okuvezwe ngokucacile ngaphambilini kungenakunqunywa. Ukuqala kwalokhu kubopha kwenzeka ezindaweni ezineziphambeko ezincane zesakhiwo, ezimweni eziningi ezingakwazi ngisho nokuqashelwa ngaphandle, noma ziqala ukusuka phezulu noma phansi.
Ingcindezi evumelekile yokhuni lwe-coniferous — kungakhathaliseki ukuthi i-spruce, uphayini noma i-fir — isethwe kokuthi 8,5 MPa, kanye nokhuni lwe-larch kokuthi 9 MPa. Ngokhuni oluqinile, i-oki noma i-beech, ithi 10 MPa.
Ngokuvamile, amandla okucindezela wangempela, okungenani ama-oki, awaphakeme kunalawo ama-conifers, kodwa leli xabiso lisafaneleka ngoba ukhuni oluqinile lusetshenziswa kuphela ezicucu ezincane ekwakhiweni, ngakho-ke izinkuni ezinamafindo amakhulu noma izinkuni ezinokuthuthukiswa okungavamile zingagwenywa. Ukhuni lwe-oki lulinganiselwe. I-oki encane, efika eminyakeni engu-30 ubudala, ibonakala iqine kakhulu futhi inamandla kunokhuni lwezihlahla ezindala.
Isigaba sekhwalithi I sivumela amandla ezinkuni ze-conifer afika ku-11 MPa, we-larch 11,5 MPa, kanye ne-oki ne-beech 12 MPa. Amanani 6 MPa okhuni lwe-coniferous, kanye 7 MPa ye-oki ne-beech asungulelwe isigaba III sekhwalithi.
Ingcindezi encike kuhlangothi lwefayibha
Esiqondisweni se-perpendicular to the fibers, izenzakalo ekuhlulekeni zihlukile kunezenzakalo ezibangelwa ingcindezi ekuqondeni kwemicu. Amandla ngaphansi kwengcindezi eguquguqukayo ancike ikakhulukazi emandleni aboniswa inani elingahlanganisiwe lezinkuni zakuqala eringini yonyaka. Ukhuni oluphuzile, lapho inani lamandla ngaphansi kwengcindezi ye-axial lincike kulo, ngaphansi kwengcindezi eguquguqukayo linendima yokusabalalisa umthwalo.
Lapho sihlola isandla esibonisa ubukhulu bamandla, sihlala sigcina isikhundla saso esiphezulu sokuhlala. Endabeni yesigaba esilayishwe ngokugcwele, amandla angaphansi kwengcindezi ehambisana nezintambo zamaconifers1/7ku1/10Amanani wamandla ekuqondeni kwemicu, kanye nokhuni oluqinile oluvela1/3ku1/5amanani wamandla ekuqondeni kwe-fiber.
Amandla aqinile
Amandla okuqina avivinywa ngezinga elincane kakhulu kunamandla acindezelayo. Lokhu kungase kube ngenxa yokuthi ukukhiqizwa nokuhlolwa kwezibonelo zokuhlola ezifanele kudla isikhathi futhi kuyabiza.
Ukungahambi kahle kwesakhiwo sokhuni kubonakala ngokusobala ngamandla aqinile. Ngokufana namandla ngaphansi kwengcindezi, ngaphezu kobubanzi bezingodo, ingxenye yokhuni sekwephuzile ibaluleke kakhulu. Ukwehluleka kwezinkuni zakuqala kwenzeka ngaphambi kokuhluleka kokhuni oluphuzile, ngakho-ke amandla okhuni lokuqala nasekupheleni awanakwengezwa. Umthelela wamafindo nokungahambi kahle kwentuthuko ugqama kakhulu kunamandla acindezelayo. Noma yikuphi ukugoba noma igagasi elibangelwa ukusondela kwamafindo, okungadingeki ukuba abe phezu kwenduku, kwanele ukunciphisa amandla okuphuka abe ingxenye yesine yamandla aqinile okhuni ngaphandle kwamaphutha.
Amaphuzu abuthaka kakhulu ezakhi ezicindezelekile ama-node esakhiwo, lapho ukuba buthaka ngenxa yezinotshi zobuchopho kukhulu kakhulu. Lapha, ikakhulukazi ezihlathini, okungukuthi ama-garters, kukhona ukucindezeleka ngenxa yokugoba ukuthi ukubala akubandakanyi.
Izingcindezi ezivumelekile zokhuni lwe-coniferous kusukela kusigaba sekhwalithi I yilezi:10,5 MAwu, kuthiwani ngokhuni lwe-oki ne-beech11 MHhayi-ke. Kuma-elementi ashubile, ukusetshenziswa kwezinto ezisuka kukhwalithi yesigaba III akufakiwe.
Izinsiza zokuhlola amandla okhuni aqinile.
Amandla okugoba
Ukuqagela okungaphansi kwefomula yokubala yokugoba Navier’s kusebenza ngokulinganisa okuhle nokhuni, kodwa kuphela emithwalweni ephansi. Emthwalweni ophakeme, ukufuduka okunjalo kwenzeka ukuthi ingcindezi yangempela yomkhawulo ngenxa yengcindezi iphansi kunebaliwe, kuyilapho isithombe esiphambene sitholwa ngenxa yengcindezi ngenxa yengcindezi. Ulayini onguziro wangempela uya ohlangothini oluqinile.
Izithombe1futhi2- Ukuphuka kwesici nokusabalalisa kwengcindezi ngesikhathi sokugoba.
Amandla okugoba abaliwe ngesikhathi sekhefu makhulu kunawo1,4ku2izikhathi zamandla acindezelayo futhi, ngaphandle kokumbalwa, angaphansi kwamandla okuqina. Uma amafindo nokungahambi kahle kwenzeka eduze nezikhathi eziphezulu kanye nokucindezela okukhulu komkhawulo, ukuncipha kwenzeka kuze kufike ku50%.
Kufanele kugcizelelwe ukuthi amandla okugoba ngaphansi kokulayisha okumile okuhlala isikhathi eside cishe ingxenye yamandla okugoba anqunywa ngendlela evamile. Uma umthwalo uphelele noma ingxenye uphindaphindwa kaningi, umthamo womthwalo uzoqhubeka nokuncipha kuye ngokuthi umthwalo ohambayo unomthelela ongakanani kumthwalo ophelele.
Ingcindezi yokugoba evumelekile ye-softwood yekhwalithi yesigaba III ithi 7 MPa, futhi kumakilasi ekhwalithi II kanye ne-I kunqunywa 10 MPa kanye 13 MPa, ngokulandelanayo. Ngosekelo oluqhubekayo ngaphandle kwamajoyinti avela ezigabeni ezimbili zokugcina, izingcindezi ze-11 MPa kanye ne-14 MPa zinikezwa, ngoba ukusekelwa okunjalo kubonisa ukuphepha okukhulu.
Uma ama-dimensioning beams evezwa ekugobeni, ezimeni eziningi akukhona ukugoba okusetshenziswayo, kodwa ukuchezuka okuvumelekile. Ngemishayo yezakhiwo ze-mezzanine, ukuchezuka ngenxa yomthwalo ongunaphakade noma owusizo akumele kudlule ububanzi obungu-1/300. Ngomsizi osekelwa ngokukhululekile olayishwe ngomthwalo osabalaliswe ngokulinganayo, isilinganiso phakathi kwe-span nobude kufanele kube umkhawulo ongu-16, ngokugoba okuvunyelwe kwengcindezi okungu-10 MPa.
Okwemishayo emifushane, elayishwe kakhulu nezingxenye eziphambanayo eziyinkimbinkimbi, ingcindezi yokugunda ibaluleke kakhulu. I-modulus of elasticity ibalulekile ekuphambukeni, kanye namandla okugoqa kanye nokubalwa kwezakhiwo ezinganqunyelwe. Ubukhulu be-modulus ye-elasticity, kuye ngekhwalithi yezinto ezibonakalayo, buhluka kakhulu. Imodulus yokunwebeka kwamaconifers ithi 10.000 MPa, futhi incike kumafayibha leli nani lithi 300 MPa ngokhuni lwe-coniferous kanye 600 MPa yokhuni lwe-oki ne-beech.
Izinsiza zokuhlola amandla okugoba okhuni.
Amandla okugunda
Uma sigundwa, ukhuni lubonisa amandla aphansi. Amanani wamandla e-shear angahluka kakhulu ngenxa yokuqhekeka kwezinkuni.
Umkhawulo ophezulu we-0,9 MPa wasungulelwa i-softwood yazo zontathu izigaba zekhwalithi. Ngokhuni lwe-oki ne-beech lwekhwalithi II kanye ne-III, inani eliphezulu lingu-1 MPa, ngokulandelanayo 1,2 MPa ekilasini I.
Uma ama-overhang amafushane kakhulu atholakala kulawa ma-voltage, kuyanconywa ukuthi ama-voltage angasetshenziswa. Uma ama-overhangs okugcina emfushane, kunengozi enkulu yokuqhekeka kokuncipha okwakheke endizeni yokugunda, okungaholela ekulahlekelweni okuphelele kwamandla okuthwala umthwalo.
Izinsiza zokuhlola amandla okugunda izinkuni.
Amandla okubopha
Uma izinduku zivezwe kungcindezi, kuyadingeka ukuhlola ukugoba ngokubala. Okubaluleke kakhulu ukukhetha okulungile kobude bokugoba. Izinduku kufanele ziqiniswe ngokuhlangana ngokumelene nokuchezuka kwezinhlangothi. Uma lokhu kungenakwenziwa ngokwezinga elanele, ubude bokugoba obukhudlwana kufanele bufakwe esibalweni.
Figures 3 kanye 4 — Izingxenye eziphambanayo ezigcwele nezihlanganisiwe ezinezimbazo ezibonakalayo nezingabonakali.
Kuma-rods acindezelwe ayinkimbinkimbi, ukubala kwenziwa maqondana ne-axis yezinto ezibonakalayo, i-x-eksisi ezithombeni.4nami4b, okufana nezigaba ezigcwele, lapho ububanzi bayo yonke induku buthathwa njengesamba sobubanzi d bezinto ezingazodwana.
Ngokuhambisana ne-eksisi engabonakali, i-y-eksisi ezithombeni4futhi,4b i4c kanye no-x-eksisi esithombeni4c, awukwazi ukuthembela ekuhlanganiseni okuphelele kwezingxenye eziphambanayo ngazinye, ngoba ukuxhumeka kwesiphambano sezinti zokhuni kuyavuna. Ngezingxenye ezimbili eziphambanayo ngokwesithombe4futhi ubudlelwano obulandelayo buyasebenza:
Amafomula oqobo okubalwa kwesiqephu esinezingxenye ezimbili.
Ama-compound acindezelwe ama-rods ngokuvamile asetshenziswa kuphela lapho izixhumanisi zidinga khona, okungukuthi lapho izingxenye ezigcwele zezigaba ezinobukhulu obudingekayo zingatholakali. Ukuze usondele ngangokunokwenzeka ezigabeni ezigcwele, ukuxhumana okuqhubekayo kwe-longitudinal kuhlala kunconywa.
Izihloko ezihlobene: ukusekela izakhiwo zokhuni, ukwakhiwa kwesitezi, amaphutha okhuni, umswakama wokhuni kanye nokwakha.