- Van tdc sid tdi han xac dinh theo bans sau: (bane 4.3)
CHirONG 5 CAC HirdNG KIEM SOAT FLITTER CHO CAU DAY VANG
CHO CAU DAY VANG
5.1. Gidi thieu chung
Can day tren the gidi chu trong tdi cac nghien ciai bien phap kiem soat ket cau ndi ehung va kiem soat khi đng lire hay kiem soat Flutter ndi rieng trong thiet ke ehdng gid cho cau dily vang. Kiem soat Flutter nhfim la lam tang van tdc gid tdi han, tuc la tranh cone trinh xa khdi rui ro mat dn dinh khi đne lue do hien tuone Fluter va tranh eay su cd cone trinh. Cd hai hudne ehfnh trone kiem soat kel cau cho ciiu day vane đ la: kiem soat tren co sd eiam tae đne nsoai ciia eid len cone trinh va kiem soat phan irng cua cau ehdng lai tae đng ngoai (hinh 5.1):
Huc'fng kiem soat thu nliuL dua iren \iec cai hien liet dien eae bo phin
chan eid cua cau hoae them eae bd phan eau lao vao tiet dien lam đne khi qua can dircrc cm thuan. ktioivj hinh thanh cac \oa> khi sau net dicn hoae xuat hien cac xoay khi be voi chu ky daị hoae khong cd sir taeh - nhap cua đng khf tren mat tiet dien. cac bien phap nay .se dan tdi lam
siam cac lire khi 6on^2. phat sinh tac dung len tiet dien. Day la hutmg
kiem soat khi dong lire cho caụ Muc tieu cua hudng kiem scat khi dong
lire la eiam ihieHi cirdng 60 cac lire khi dgng phat sinh.
- Hirdng kiem soat thu haị bang each them vao cac thiet bi giam chan co
hoc cd tac dung phat sinh them lire can (bd sung vao lire can cua ket cau) dé hap thu nang luglig dao done hay phdl sinh lire ngoai ehdne lai cac tac dune cua kich dgng gid. Da> la hinVng kiem soat co hgc. Hudng ki^^^m .soat CO hgc na> cd liieu qua lot Ndi cac tac done cua hien tirctng dao dgng cirong hue Na dao dong ngdu nhien do gid. Muc tieu cua bien phap kiem
soat ca hoc nham lang luc cụ cua cone innh bane each hap thu nang
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Kiem sojt cau lao khí(Jong lac I , 3 i^ 'J •= 1 u, Sf* .p^ 5 .c .c _ < J C '_ -2 ^ ' i ? — ,_ ~ O
Kidm soiii Flutter cho cau dav vane
Kiem soil CO hoc
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Hinh 5.1. So đ cac hudng kiem scat Flutter cho cau day vang
Trong ehuong nay se trinh hay tdng quat \L^ kiém soat ket cau cau day vans ehdng lai lac dung eiia hien lugng mat dn dinh khi dgng lire Fluller iheo hudne kiem soal khf dgng lire va hudng kiem soat eo hoc.
5.2. Kiem soat khi đny luc
Cac bien phap kiem soat khf đng lue duge sir dung rat rong rai trong thiet ke cau day vang. Hudng kiem soal khi đng lire bao gdm eae bien phap ehinh sau: tane eudng do cung ket cau (cai bien kel eau), eau lao mat cat ihoal khị ihem eanh thoat khf va thiet bi hudng đng khf.
TiU}<^ eu&fig do cung ket cau: Do eirng udn. xoan \a phan bd khdi lugng tren
dam cune ket eau cau dav vane ludn la veu to can .\em \ei irirde lien \a thiet ke dam
ludn theo hudng lang eudng do eung udn va .xoan. dae biet ehu trong lang do eung
xoiin. Vice lang do eímg na\ se d:^n ldi viee lang lan so dao dong rieng eo ban \a kel qua lam lang \an tdc gid ldi han. Phan bo khdi lugng tren ket eau anh huemg khdng nhieu ldi dieu kien dn dinh. ui\ nhien. khoi luong idn ht^i eua dang mat eai
be long hay ihep be long lien hgp thudng eho dn dmh khi đng hon so \o\ dang mai eiil dfim ban. mang dam ihep - mai eau kin true huong co khdi luong nhe hon.
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Melt cat thoat khi: Vdi dang mat cat iho nham cd sd Revnold Idn thi done khf
di qua se phat sinh cac xoay Karman kich thude Idn, cd sir tach-nhap cua đng khf ngay tren mat dam, ket qua la phat sinh cac luc khf đng eudng do Idn. bien đi phuc tap va đ dan tdi su ket hgp giira dao dong udn va dao đng xoin gay ra mat dn dinh Flutter. Do vay, xu hudng hien nay la ap dung cac dang mat cat thoat khi dong lire nham tang eudng on dinh khf đng cho cau day vang.
Cau tao ccmh thocU kh i: Canh thoat khf duge thiet ke cung vdi mat cAi dam
hay them vao mat cat dam cd tac dung lam đng khf em thuan khi di qua cdng trinh, giam kha nang lao ra vung trdng va cac xoay Karman kfeh thude Idn sau cdng trinh. Canh thoat khf thudng duge ehia 3 loai chfnh: canh thoat khf dang canh, canh thoat khf dang thudn va ban phan ludng khf. Mgl sd dang canh ihoat khf dung trong dam cau day vang duge minh hoa tren hinh 5.2.
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Hinh 5.2. Mot sd cau tao canh thoat khf ihem vao tiet dien dam
Thiei h, hi«rn^A don^- Tlịet b. hudne đng ciing 6iioc them vao net dien dam
cUi cd tac dune eidne nhu canh ihoạ khi lam done kh, em ihuan khi tho, qua cdụ
Co the bo tn lh,el b, huone done iren suọ chieu dạ cau h.o chi mo, phan chieu dai
nhip. Moi so minh hoa ,h,ci h, huone dong dune uong dam cdu đ> vang duoc the hien lien hinh 5.3
tt L ^ ^ Thieibi i huong done
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Hmh 5.3. Mdt sd cau tao thieibi hudng đng them vao tiet dien dam