222 M6 hinh phan td huu han dg giai bai toan danh chim khdi chan dg cdng trinh..
M O H I N H P H A N TlT HlTU H A N D E G I A I BAI T O A N D A N H C H I M K H O I C H A N DE C O N G T R I N H B I E N BANG T H E P TlT SA LAN
Dinh Quang Cudng Vien Xdy dung Cdng trinh Bien
TOM TAT
Bdo cdo ndy trinh bdy viec md phdng hi thdng kit cdu phuc vu tinh todn van chuyin.
ddnh chim khdi chdn di (KCD) cdng trinh biin bdng thep tie sd lan (SL) bdng chuang trinh theo phuong phdp phdn tic hiru hgn.
GICKI THIEU CHUNG
Qua trinh danh chim KCD cdng trinh bien bang thep trong dieu kien bien lang dugc md phdng theo bdn giai doan:
• Giai doan 1: KCD trugt tren dudng trugt cua SL ve phia ban xoay.
• Giai doan 2: KCD trugt va xoay quanh trgng tam cua ban xoay den chdt an toan.
• Giai doan 3: KCD lat nghieng tren ban xoay.
• Giai doan 4: KCD tach khdi SL.
Phuomg trinh dao ddng cua he thdng dugc thiet lap theo cac giai doan va dugc giai tren mien thdi gian [1, 2]. Trong qua trinh danh chim, he thdng SL-KCD cd tac ddng tuomg tac. Tinh tuomg tac cua he thdng duge md ta theo dieu kien chap chuyen vj, chap van tdc va gia tdc cua SL-KCD tai mat (va cac diem) tiep xuc. Cac dai lugmg: chuyin vj, van tdc, gia tdc, lyc tuomg tac va lyc thuy ddng cua he thdng dugc xac djnh theo thdi gian trong sudt qua trinh danh chim.
Gia thiet SL-KCD la mdt he thdng ddi xirng va ehi md phdng sd cac giai doan 1, 2 va 4. Hai giai doan dau can xem xet sy can bang cua he thdng tren mat dumg vdi lyc thuy ddng tac dyng len he thdng SL-KCD trong khdng giai ba chilu.
MO PHONG HE T H O N G
L He toa do diing de md phdng
Su dyng nam he toa do chinh (Hinh 1).
Tuyin tap bao cao Hdi nghj KHCN "30 nam Dau khi Vift Nam: Cff hdi mdi, thach thde mdi" 2 2 3
INPUT
SYSTEM Z A
Launch Runner
WATER SURFACE
GLOBAL SYSTEM
Jacket Members Contacting Launch Runner
Rocker Arm
ZL-
GLOBAL SYSTEM INPUT SYSTEM
y * INPUT
SYSTEM
STARBOARD
Launch Runner
FORWARD
BARGE
T
0 1
Joint 2
Joint 1
Joint 4
Joints
1
I
AFT X
w
LAUNCH DIRECTION
P
P ORT i^^i Members Contactii^
Launch Ruimei
T: Trailing edge distance in x-direclion
L: Length of rocker v n D: Height of rocker arm
Joint 1: Port side Uailing point Joint 2: Starboard side trailing point Joint 3: Port side leading point. Joint 4: Starboard side leading point
Hinh 1: He toa do dau vao, he toa do tong the va vj tri ban dau ciia KCD
fl. He tog dp ddu vdo
He toa do dau vao dugc su dyng de md ta nhdng sd lieu v l dac tnmg ban dau cua SL, KCD va nhimg sd lieu ban dSu lien quan d i n qua trinh danh chim. Nhin chung, he toa
224 Md hinh phan td huu han de giai bai toan danh chim khoi chan de cong trinh...
do d4u vao dugc coi nhu he tga do tdng the cua ket cau dung de md hinh boa ket eau KCD. True X trong he toa do dau vao song song vdi mat nude va chay dge theo tryc trung tam (dge theo dudng sdng ehinh) cua SL ve phia ban xoay - la hudng danh chim.
b. He toa dp dja phuang ciia sd lan
He toa do dia phuang cua SL lay goc la trgng tam cua SL (Hinh 2) dung de md ta chuyin ddng tuang ddi gida KCD va SL trong hai pha dau tien cua qua trinh danh chim.
c. He toa dp dia phuang cda KCD
He toa do dia phuang eua KCD \ky gde la trgng tam cua KCD (Hinh 2).
d. He toa dp dja phuang cua bdn xoay
He toa do dia phuang cua ban xoay l4y gdc la chdt an toan - chu yeu de md ta giai doan 2 cua qua trinh danh chim va md ta lyc tuong tac giua SL va KCD (Hinh 3).
e. He tog dp tdng the
He toa do tdng thi ISy gdc tai mat nude thang vi tri cua trgng tam SL trudc khi thyc hien qua trinh danh chim. He toa do tdng the lay cac hudng X,Y,Z cung vdi hudng cua cac tryc cua he toa do dAu vao. Chuyin ddng cua SL, KCD va cac lyc thuy dgng dugc md ta trong he toa do tdng the (Hinh 1).
Cac he toa do deu lay tryc X hudng tu mdi den lai sa lan (theo hudng danh chim), true Z hudng len, tryc Y xac dinh theo quy tac ban tay phai. De cd the chi rd diem dan hudng, diem dat tdi, banh trinh cua tdi va vi tri KCD tren dudng trugt, gia thiet rang dudng trugt song song vdi dudng sdng cua SL.
Global SystatZ
JackEtSysKm
Global Syslcnj
WkTHl SUIfACE
BaiseSTStffli
Hinh 2: Vj tri can bang ban dau cua he thong gom sa lan va khoi chan de
Hinh 3: He toa do dja phu"OTig ciia ban xoay
Tuygn tap bao cao Hdi nghj KHCN "30 nam DJiu khi Viet Nam: Co hgi mdi, thach thde moi' 225
4 z
JadulMockl
Buje Model
RockrAm
Global System X
Hinh 4: Khdi chan de va sa lan trong he toa do dau vao
2. PhiroTig trinh ddng lyc hoc ciia he thong
Hinh 5: He toa do bieu di^n cac luc va mdmen
Cac lyc tac ddng len he thdng SL-KCD can dugc xac dinh bao gdm lyc quan tinh, trgng lyc, lyc ma sat, ap lyc thuy tmh va lyc thuy dgng va phuang trinh chuyen ddng tdng quat dugc thiet lap cd dang:
MX + CX + KX ^F (1) Trong dd: M: Ma tran khdi lugng cua he thdng trong he toa do tdng the
C: Ma tran can cua he thdng trong he toa do tdng the K: Ma tran do cijmg cua he thdng trong he toa do tdng the F: Vecta lyc tac dyng len he thdng
X,X,X: Cac vecta gia tdc, van tdc, chuyen vi tai nut ludi PTHH cua he thdng. Phuang trinh chuyen ddng (1) la phi tuyen va viec giai dugc thyc hien quen thudc tren mien thdi gian.
3. Md hinh hoa he thdng
Cac sd lieu ban dau dugc dua vao nhd mgt modun chuang trinh, bao gdm: trgng tam cua SL, bude thdi gian dung de tinh toan, vi tri ban dau cua KCD tren dudng trugt cua SL, cac dac trung cua ban xoay.
SL dugc md phdng bang cac phan tu phang, mdi phan tu phang dugc md ta thdng qua tdi da 8 diem. Thu ty danh sd nut theo chieu kim ddng hd hoae vdng trdn, su dyng quy tac ban tay phai de xac dinh hudng cua phan tu. Mdi phan tu cd mgt vecta phap tuyen (ehi budng) cac vee to phap tuyen chay khep kin, theo dudng hinh dang cua than SL.
Khdi chan de dugc md ta trong he toa do dau vao theo phuang dung (Hinh 4). Mat tilp xuc cua KCD va SL se dugc chuang trinh ty dgng md ta bing each xoay KCD tu phuang dung sang phuong ngang song song vdi dudng trugt. Vi tri ban d§u cua KCD
2 2 6 Mo hinh phan td hdu han de giai bai toan danh chim khoi chan de cdng trinh...
dugc xac dinh nhd vi tri ban dau cua tdi keo va cao do tuong doi cua ban xoay vdi chdt ham frong he toa do dau vao. Gia thiet rang be thdng SL-KCD doi xung va khdng can thiet quan tam den cac vi tri tren phuong Y.
Mat tiep xuc cua KCD vdi SL dugc md ta nhd bdn diem chuan bao gdm: diem 1 va 2: cac diem dat luc keo d cudi sa lan, diem 3 va 4: cac diem dan hudng). Diem dat lyc tdi la diem cudi cua phan tu tiep xuc cua KCD vdi SL tren dudng trugt (Hinh 1).
4. Vi tri can bang ban dau ciia he thdng
De md phdng qua trinh danh chim, he thdng SL-KCD dugc gia thiet can bang tinh dudi tac ddng cua trgng luc va luc thuy ddng. Vi tri can bang ban dau dugc xac djnh bang chuong trinh dua vao ma tran khdi lugng, vi tri trgng tam, cac dac trung hinh hgc, vj tri tuong ddi giua SL va KCD. Chuang trinh khdng the ty ddng quan ly cac lyc va mdmen khdng ddi xung (neu cd), vi vay nhiing tai trgng phy trg va tai trgng lech tam can dugc true tiep dua vao.
5. Khdi lu-ong ciia he thdng
Ben canh hinh dang ket cau KCD, viec tinh toan danh chim cdn phy thudc nhilu vao khdi lugng cua he thdng SL-KCD. Ma tran khdi lugng cua ket cau KCD dugc xac djnh ty ddng trong chuong trinh, ma tran khdi lugng cua sa lan can dugc true tiep dua vao.
6. Mo hinh hoa tac dong ciia tdi
Tdi dung de keo KCD dge theo dudng trugt cua SL din ban xoay. Gia thilt ring, toe do tdi la hang sd va qua trinh keo dien ra du cham de cd the coi tac ddng tdi la tinh. Tdi keo cho tdi khi van tdc trugt cua KCD dat tdi tdc do tdi, tu dd KCD tu trugt tren dudng trugt.
7. Lyc thuy dong va cac he sd
Tai trgng sdng tac dung len KCD trong qua trinh danh chim dugc xac dinh theo cdng thuc Morisson. Tai trgng sdng tac dyng len sa lan dugc xac djnh thdng qua cac he sd thuy ddng va he sd can. He sd beo the tich va he sd can dugc dua vao tinh toan thdng qua cac dai lugng khdng thu nguyen.
Cdc hi sd beo thi tich dugc tinh nhu sau:
• Ddi vdi cac chuyen vi dung va lie A|,/M i = l , 2 , 3
• Ddi vdi cac chuyen vi xoay AJ,/IJJ, i = 4, 5, 6 Cdc hi sd cdn dugc tinh nhu sau:
• Ddi vdi cac chuyen vi thing Bij/M * (L/g)"^ i = l , 2 , 3
• Ddi vdi cac chuyin vi xoay B„/M*(L/g)"^ * (1/L)^ i = 4, 5, 6 Trong dd: I,|, L: Mdmen quan tinh va chilu dai cua sa lan
g: Gia tdc trgng trudng
A, B: Cac kich thudc cua mat cat sa lan theo cac phuong M: Khdi lugng cua he
Tuygn tap bao cao Hdi nghj KHCN "30 nam Dau khi Viet Nam: Cff hdi mdi, thach thde mdi" 227
8. Tai trong
Chuong trinh tinh toan danh chim cd the ty dgng xac dinh cac trudng hgp tai trgng tai cac thdi diem danh chim bao gom: lyc day ndi; lyc thuy ddng; lyc tuong tac giua SL va KCD; lyc quan tinh.
- Lyc day ndi va lyc thuy dgng chi xuat hien d cac phan tu ngap nude.
- Lyc quan tinh phy thudc vao gia tdc va van tde eua he thdng.
- Luc tuong tac giua KCD va SL xuat hien tai phan tiep xuc cua cac phan tu kit cdu vdi dudng trugt va mang trugt. Chuang trinh chap nhan gia thiet: ban xoay lien kit cung vdi KCD, lyc tuong tac phan bd deu dge theo cac phan tu tiep xuc.
KET QUA TINH TOAN
Kit qud tdm tdt: Cac thdng sd danh chim, vi tri ban dau, trgng lugng va lyc day ndi, tdm tat qua trinh chuyen ddng, mdn nude.
Kit qud chi tiit: Phan lyc gdi tya, van tdc va gia tdc cua he thdng SL-KCD tren sau phuong, phan lyc len ban xoay, cac loai lyc va mdmen tac ddng phat sinh trong qua trinh danh chim. Ket qua dua ra cd the lua chgn theo cac bude thdi gian trong qua trinh danh chim. Cac ket qua chi tiet dugc dua ra dudi cac dang sau:
- Ma tran khdi lugng cua KCD: Ma tran khdi lugng va ban kinh xoay cua KCD da dugc dua ra trong he toa do dau vao vdi KCD d vi tri ban dau, trudc khi KCD chuyen ddng va ha xudng dudng trugt (Hinh 4).
- Cac thdng sd cua he thdng: Thua nhan he thdng SL-KCD can bang tinh dudi tac dyng cua trgng luc va lyc thuy dgng khi md phdng qua trinh danh chim. Vj tri can bang ban dau (khi KCD nam tren dudng trugt) dugc md ta bang sy can bang cua trgng lugng cua KCD dat tai trgng tam vdi lyc day ndi dat tai phu tam (Hinh 2). Quy dao xoay cua SL ddi xung qua gdc toa do dia phuang cua SL. Vi tri cua chdt ham an toan dugc dua ra tren he toa do dau vao vdi dudng trugt cua SL song song vdi tryc X cua he toa do dau vao, trudc khi he thdng SL-KCD dat dugc vi tri can bing ban diu (Hinh 4).
L Trong lirotig, lyc day ndi va vj tri ban dau
Trong he toa do dau vao, trgng lugng va lyc day ndi cua KCD dugc xac dinh va dat tai trgng tam KCD trudc khi xoay va dat KCD xudng dudng trugt (Hinh 4). Trong he tga do tdng the, toa do cac trgng tam va khoang each giiia cac trgng tam dugc xac dinh (Hinh 2,4).
2. Vj tri ciia cac vat the trong he thong
Vi tri cua SL(sau bae ty do) dugc chi ra tren he toa do tdng thi trong mat phang XY trung vdi dudng mat nude. Vi tri cua KCD (sau bae tu do) dugc chi ra tren he toa do tdng the va he toa do dia phuang cua SL.
a. Giai dogn 1
Chi cd chuyin ddng tuong ddi giua KCD va SL tren SL theo phuang X cho din khi KCD nim tren dudng trugt.
b. Giai doan 2
228 Md hinh phan td huu han dg giai bai toan danh chim khdi chan dg cdng trinh.
KCD trugt va xoay tren SL trong mat phang XZ va nghieng tren SL trong he toa do dia phuang cua SL.
c. Giai dogn 3
KCD tach khdi SL, sy chuyen dgng dugc hoan tat.
3. Van toe va gia tdc cua he thdng
Van tdc va gia tdc cua SL dugc chi ra tren he toa do tdng the dat tren mat phang X-Y trung vdi mat dudng nude. Van tdc va gia tdc cua KCD cung dugc chi ra trong he toa do tdng the va trong he toa do dia phuang cua SL.
4. Lyc tac dijng
Cac lyc tac dyng giua KCD va SL dugc chi ra trong he toa do dja phuong cua ban xoay gan tren ban xoay vdi phuang cua true Z ludn ludn tryc giao vdi mat tren cua ban xoay va tryc X ban dau cua hudng danh chim (Hinh 3), tryc Y cua ban xoay dugc xac dinh theo quy tac ban tay phai.
5. Lyc va mdmen tac dung trong qua trinh danh chim
Lyc va mdmen tac dyng len sa lan dugc chi ra trong he toa do dia phuong cua SL va trong he toa do tdng the vdi cac chieu X-Y-Z trung vdi chieu cua he toa do dja phuang - hinh 5. Cac lyc va md men tac dyng len KCD dugc chi ra trong be toa do dia phuong cua KCD va trong he toa do tdng the vdi cac chieu X-Y-Z trung vdi chieu cua he toa do dia phuong (Hinh 5).
6. Chuyen dong giai doan 1
Trong giai doan 1, chuyen ddng cua SL dugc xac dinh trong he toa do tdng thi.
Chuyen ddng eua KCD dugc md phdng la chuyen ddng tuong ddi vdi SL theo hudng X trong he toa do dia phuang cua SL. Hudng X cua he toa do dia phuang cua SL cd thi khdng trung vdi hudng X cua he toa do tdng the nlu sa lan cd chuyin ddng xoay. Chuyin ddng quan trgng nhat cua SL la xoay nghieng dge tai cho, nhdi len va lie ngang, cac trudng hgp nay dugc md ta trong ket qua tdm tit. Cac thdng tin vl cac chuyin ddng khae tim trong ket qua chi tiet.
Global Systm X Bar^eSyitdn
Hinh 6: Giai doan 1
Tuyin tap bao cao Hdi nghi KHCN "30 nam DSu khi Viet Nam: Cff hgi mdi, thach thde mdi" 229 7. Chuyen dong giai doan 2
Trong giai doan 2, chuyen ddng cua ca he thdng SL-KCD dugc xac dinh trong he toa do tdng the. Van tdc tuong ddi cua ban xoay (banh xe) duge xac djnh trong he toa do dia phuong cua ban xoay. Vi tri tuong ddi (phuang X) trong he toa do dia phuang cua sa lan khdng thay ddi so vdi trudng hgp 1. Ban xoay va lyc tuong tac trong ban xoay theo phuong Z dugc xac dinh. Luc tac dung len ban xoay theo phuang Y cd thi tim trong kit qua chi tiet. Chy y rang phuong cua true X trong he toa do dia phuang cua ban xoay cd the khae vdi phuang X trong be toa do tdng the hoae he toa do dja phuang cua sa lan khi ban xoay boat dgng (xoay). Chuyen dgng quan trgng nhit cua he thdng la xoay nghieng tai chd (lao xudng), nhdi len va lie ngang, cac trudng hgp nay dugc md ta trong kit qua tdm tat. Cac thdng tin ve cac chuyen ddng khae tim trong kit qua chi tilt.
Global SystenZ
Rocker Aim System Z Barge System Z
Jacket Rd Motion
Rocker Aim
BargeSystanX Angle ^^^^^^
System X
Hinh 7: Giai doan 2 8. Chuyen ddng giai doan 4
Trong giai doan 4 chuyen ddng cua he thdng SL-KCD dugc xac dinh trong he toa do tdng the. Tu khi KCD rdi khdi SL, chuyin ddng ddc lap cua KCD dugc md ta trong tap ket qua. Doan dudng chuyen ddng cua KCD dugc xac dinh nhd vao cac dilm cd lien quan da md phdng.
V
i
Globa System Z
\
\
\
Jacket
Global System X
Barge
Hinh 8: Giai doan 4
230 M6 hinh phan td hdu han de giai bai toan danh chim khoi chan de cdng trinh...
9. Mdn nude va chieu chim ctia KCD
Mdn nude dugc xac dinh nhd cac diem tren dudng mat nude. Chieu chim dugc tinh toan nhd cac diem lien quan da md phdng.
Global Coordinate System
Deepest Point
Hinh 9: Mdn nirdc va chieu chim KET LUAN
He thdng SL-KCD da dugc md phdng nhu tren day ed the dugc tinh toan bang cac chuong trinh chuyen dyng: StruCAD*3D; StrabCAD va NepTune.
Vien Xay dyng Cdng trinh Bien da va dang su dyng cac chuang trinh chuyen dyng neu tren day de tinh toan ket cau khdi chan de trong trang thai khai thac va thi cdng. Cac ket qua tinh toan tu cac chuang trinh chuyen dyng dam bao do tin cay, dugc dang kiem qudc te chap nhan.
TAI LIEU THAM KHAO
1. Bathe K.J., 1992. Finite element procedures in engineering analysis.
2. Bathe K.J., 1996. Finite element procedures. USA.
3. Peter Bettes, 1993. Infinite element. London.
4. Softwares: StruCAD*3D; StrabCAD; NepTune developed by Zentech, USA.
