THONG BAO KHOA HOC NGHIEN ClTU PHl/ONG PHAP KIEM TRA DO BEN CHUNG SU^ DUNG TRONG BAI TOAN TOI U*U HOA KET CAU TAU VO THEP THEAPROACH VERIFIED AN ULTIMATE LONGITUDINAL STRENGTH FOR APPL
Trang 1THONG BAO KHOA HOC
NGHIEN ClTU PHl/ONG PHAP KIEM TRA DO BEN CHUNG
SU^ DUNG TRONG BAI TOAN TOI U*U HOA KET CAU TAU VO THEP
THEAPROACH VERIFIED AN ULTIMATE LONGITUDINAL STRENGTH FOR APPLIED TO STRUCTURAL OPTIMIZATION OF STEEL SHIP
Phqm Bd Linh'
Ngiy nhln bai: 28/3/2014; NgJy phan bien thong qua: 05/5/2014; Ngay duyel dang- 13/8/2014
T O M T A T
Bdi bdo cong bo thuat todn cua chuang trinh linh todn do ben chung ldu vo thep du&i tdc dtfng ctia mo men uon doc theo phuang phdp Smith su dung trong bdi loan lot uu hoa kit cau tdu vo thep Dp tin cgy cua chuang trinh dugc chung minh bang cdch SO sdnh vai cdc kit qud ihuc nghidm tren mo hinh gan dung da dugc cong bo cua cdc nghien cuu khac
D WT dong tai Nhd may Dong tdu Nha Trang
Tirkhoa: dg ben chung, mo men uon dgc, phuangphdp Smith
A B S T R A C T
This paper publish the program lo generated the ultimate longitudinal strength of steel ship under vertical bending moment according to Smith method for applied to structural optimization The reliability of this program demontraled by comparison the result with many experiment models which published on the world The program applied to calculate the ultimate longitudinal strength, in structural optimum problem, of bulk carrier 2000 DWT was built at Nha Trang Shipyard Keywords: ultimate longitudinal strength, vertical bending moment Smith method
i DAT V A N D £ khdng dugc thoa man theo dieu kifin quy pham, &ii
Trong bai toan toi uu hda k i t cau tdu vd thep, nd khong dugc chap nhdn vd ngugc Igi [9] vific danh gid muc dd thda man di4u kifin toi uu theo , „ , _ ^ L » ^ • L
-^- ^ ^ • 3 ^ 1 Khai mem do ben Chung tau vo thep
rat nhidu phuong dn, chdng hgn nhu bp thdng so
kfit cau sau t6i uu cd thoa man dieu kifin dg ben
on dinh, hinh hgc , trong dd phuang dn thda man
dieu Kifin dp b4n chung dudi tdc dgng ciia mfi men
Ket cdu vd tdu thuy (sau day gpi chung Id vd tdu) Id mfit hfi thfing ket cau tam gia cudng phipc tap bao gom nhieu thanh phan nhu k i t cdu boong,
1 J '^ , ' , " ,.* - "a " n •- day, man, vdch ngan, sudn vd gia cudng theo
uon dgc tau la quan trgng nhdt va dugc Quy phgm 7- s- » ^ _ , *
quy ainh [3] Da co nhilu phirang phap tinh dp b i n P''''""9 ="= ' ^ " ' • '"°'^ ^'^ '"^" ^'^" ""^'^ """= Chung ciJa & v6 thep dudi tac dung cua m6 men "" >^"3 •'°= 1^" """"^ • * " " ' " " " " ^ " S ' ^^ ^" ^ u6n doc, tuy nhien phi/ang phap Smith (4], [7] d w c * ! " <^ "V^S b*i ngoai iipc nho horn gi^ trj thilt k l SLP dung nhilu hon ca t)*i tinh u'u viet cija n6 va da ''"V nhien, ngoai Ivc tac dung len tiiu IS ngiu nhiSn,
duoc Quy pham lACS [8] iJng dung Bai b^o nay khSng co dinh boi y i u t l thien nhien cua dilu ki#n
xay dung chuong trinh tinh do b i n chung tSu vo s6ng biln va sv phan bo khong diu cung nhu trang
thep theo phucmg phap Smith va si> dung n6 d l thai tal trpng khong lien tuc cua hang hda tren tau kilm tra dilu ki#n rSng bupc cua bp thdng s6 k i t Trong v^i truong hpp hilm hoi cac I^FC tac dung nay cau, n l u dO ben chung cua tau theo bp thong so k i t cd t h l dat tai gia trj thilt ke va lam cho tau c6 t h l cau nay (tinh theo phuong phap cua bai bao nay) pha huy cue bO hoac toan bp
' ThS phgm BS Linh- Khoa Xay dung Tfufirng Dgi hpc Nha Trang
Trang 2Hinh 1 T&u bi phA hiiy do mat dn dmh
Khi eac Ig'c tdc dgng ndy vugt qud gia trj thiet
k6, cdc ph^n tCK k i t cdu vo tdu se bj mat on djnh d
phan chju ndn vd ehdy deo d phdn chju keo Vd neu
nhu cdc liJc ndy tilp tgc tang Idn nUa se xdy ra hifin
tugng m^t fin dinh vd pha hOy nhieu hun nOa cde
d i n khi dat dugc trang thai tdi han cua todn bd k i t
cdu vd tau Liic nay ggi dd la gia trj do ben ehung
hofic gid trj dfi ben tdi han cCia vd tau
C/ dieu kifin biln ddng, hay dilu kien sdng gid
tdn, tijy vdo dieu kifin sdng biln tdc dgng len vd
tau md trang thai tdi h^n ed hai d^ng khde nhau,
hifin tugng tdu trfin dinh sdng (hogging condition)
t h l hifin phdn eh]u kdo d phia trfin boong vd phin
ch[u nen d phia ddy tdu, trong khi dd hien tugng
tau dudi ddy sdng (sagging condition) thi cd phan
men u6n dpc tdu, q = k I\d gdc nghieng dgc cua
hai mgt cdt ngang k l nhau tgi vi tri mot sudn, k Id dfi
cong cua mgt eat ngang tai v[ tri sudn dang xet vd
/ la khodng cdch giua hai mdt eat ngang dang xdt,
thudng la khodng each sudn
2 Phuvng phap xac djnh dg ben chung cua tau thep
Hien nay, ed t h l thong ke duge 4 phuong phdp
tinh dfi ben chung eiia tdu vd thep nhu sau:
- Phuung phap Caldwell: la phuang phdp dau
tien dugc nhd khoa hoc Caldwell [6] gidi thifiu nam
tam gia eudng giong nhu Id eac tam khdng gia
cudng vdi dfi day tuung duong TCf do tinh todn
md men uon deo todn phan (fully plastic moment)
cua mdt cat ngang dd, cd xdt den dnh hudng cda
hifin tugng mat 6n djnh Doi vdi cdc phdn bj mat
on djnh il'ng suat d phan ddo {phdn bi kdo) duge
factor), gia trj ndy vdn chua dugc chirng mmh
thda ddng vdo thdi dilm ay Dieu dd cho thay, gid
tn Idn nhat ed dugc eua tdt cd cdc phan tu ket cdu
la gid trj dfi ben tdi han Tuy nhien, trong kit c l u
khi niim ty d^y B6ng (sagging condition) |8|
thgc thi dilu dd khong chinh xdc bdi vi bien dang tuyin tinh dugc phdn b6 v l phia dudi eua mgt cdt ngang, vd thdi gian md dp bin tdi hgn dat dugc (hoae edn ggi Id thdi gian t r i , time lag) Id khde nhau giCra cdc phdn tir k i t cdu rifing Id
- Phueng phdp Smith: Sau Caldwell, nhiJng thdng tin chinh xde hon cua hfi so gidm irng suit da duge xdc djnh theo dnh hudng eiia hifin tugng mat
I n djnh Tuy nhifin, v i n d l gdy ra bdi hifin tu'ong thdi gian tre ndl tren v l n khdng dugc giai quylt cho d i n khi Smith [1] d l xult mdt phuang phap dan gidn md ngdy nay thudng goi Id phuang phap
pha huy tang d i n tren mgt cat ngang cua vd tdu gay
ra bdi mfi men uon dgc Trong phuang phdp Smith, mat cdt ngang dugc phdn chia thdnh cac phdn tip
he irng suit trung binh vd bien dang trung binh (average stress - average strain) cua tirng phdn ti> rifing lfi dugc xdc d|nh bdi Igc dgc trgc vd cd xet
d i n dnh hudng cua hifin tugng deo vd mat on djnh
Sau dd, vide phdn tich phd hiiy tang dan Suiyc bilu
difin bdng tong cac lgc eua cdc mat cdt ngang cdn
ung dga theo m6i quan hfi irng suit trung binh va biln dgng trung binh cua nd
- Phuang phdp phan tir hitu hgn phi tuyen (nonlinear finite element method): day Id phuang phap mgnh nhit d l bilu difin su phdn tieh phd huy tang dan ciia vd tau Ndl mfit cdch ting qudt, vo tdu
Id mfit kit cau qua Idn d l co t h l bilu difin sg phdn tich phd hiiy tdng dan bang cdc phuo'ng phap phin
ddng khi sir dyng phuang phdp phin tu huu han phi tuyin bang cdch sir dgng cde phin mem thuang
MSC-Nastran d l tinh toan md phdng
- Phuang phdp ISUM (Idealized Staictural Unit Method): ddy Id phuang phdp bieu dien sg phdn
Trang 3tich pha hiiy tang d i n tgi vj tri sudn cua vd tdu Lue
nay, cdc phin tip mdi (khde vdi phan tir ciia phuang
phap Smith) dugc su dgng d l bilu dien su phdn
tich phd hiiy tang d i n cua vd tdu dudi tdc dyng eua
phipc tgp han da dugc gidi thieu vd v l n edn tilp tgc
phat triln nu'a
3 Vai trd cua phuong phdp k i l m tra dg ben chung
trong bd) toan toi u u hda k i t c l u tdu vd thep
Trong bdi todn toi uu, cdc thdng so cua mgt
cdt ngang tdu ludn ludn thay d i i (chilu ddy tdn vd,
chieu ddy song chinh, s6ng phy ) vd mdi lan cdc
thong s6 ndy thay doi Igi t i l n hanh kilm tra dilu kifin
dp ben chung cua tdu Nhu vfiy trong qud trinh tinh
toi uu se lifin tgc tinh todn gid trj dfi bin chung sau
moi lan thay doi cdc thdng so mgt d t ngang Xdy
dung thudt todn kilm tra dfi ben chung cd t h l k i t
nil cde phucrng phap trfin vdi chuang trinh tinh t l i
uu k i t c l u la dieu can thilt trong bdi todn toi uu hda
ket cau Trong khudn kho bdi bdo nay, tdc gia cong
bo chuang trinh kiem tra dfi ben chung tdu vd thdp
(hay dp b i n tdi han) theo phuang phdp Smith
II 061 TU'ONG VA PHU'O'NG P H A P NGHlfiN CI>U
1 Ddi t u g n g nghien c u u
B l i tugng nghifin ci>u Id chuang trinh kilm tra dfi bin chung tau v6 thdp theo phuang phdp Smith, ung dgng cho tdu chd hang rdi 2000 DWT do Nhd mdy Odng tdu Nha Trang sdn xult ndm 2001 [2] theo quy phgm phdn cap vd ddng tdu bien vd thfip TCVN 6259:1997 vd dugc Ddng kilm Vifit Nam kilm duyfit
2 Phuo'ng phdp nghien ciru Rit nhilu cfing trinh nghifin euu da cdng bo v l vific ddnh gid dfi bin chung ciia tdu bang phuang phap Smith, vd hifin nay T 6 chue Dang kilm lACS (Intemational Association of Classification Societies) [8] dd dua vdo quy phgm each xde djnh
dp bin chung cua tdu theo phuang phdp nay Do vdy, d ddy trinh bdy eg the phuang phdp Smith de xde djnh dfi ben chung cOa tau
- Phdn chia mgt edt ngang ciJa tdu thanh nhdng phan tir bao gom n?p gia cudng c6 lifin k i t vdi tfin tam (hinh 2)
V ' V ' V,'
>6.iAii<
H I 1
-'
y' \ ' '
AJ->Ai,y
y ardnglbeo
- I I
-'
a (3 vj tri m ^ v^ boong
Hinh 2 Vi dy ve vifc pha
- Tdng d i n dfi cong cua vd tdu vdi gid su rang
mat cdt ngang cdn phang vd hifin tugng ufin xay ra
doi vdi trye trung hda hifin t^l cCia mgt cat ngang dd
- Xac djnh dfi ben dgc tnjc cua cdc phin tip ket
c l u rifing bifit (irng suit ciia phin tir dugc suy ra
tir biln dgng) dga tren moi quan hd ung suat trung
binh vd biln dgng trung binh
- Xdc djnh dp ben u6n cua mgt eit ngang bing
tich phan t i t ca dfi ben dpe true cua cdc phin td k i t
u l n la tdng cdc gia trj dugc tich luy ndy
Gid tri dfl b i n chung (hogc md men uon chung
hogc Id md men uon tdi hgn) M^J duge djnh nghJg
uon dgc M va do cong k (hodc gdc xoay q) cua mdt
d t ngang vd tdu Gid trj md men u l n M, tdc dfing
cho tCrng budc tdng d i n ciia todn bfi qud trinh Dfi
b d vj tri v^ch dgc
n chia cic phan ta
d t ngang vd tdu theo trgc trung hda, nd Id nguyen nhan gdy ra bien dgng dpc tnic £ trong mdi phin tir kit c l u Trong dleu kifin tau dudi ddy sdng, phin tip
dd nhu'ng phin tu phia tren tnjc trung hda se bj ndn
Gid tri uii\g suit a trong mdi phan tu k i t c l u dugc
trung binh vd biln dgng trung binh o-e eua mfii phan
ciia m5i phin tu k i t d u Khi biln dgng ciia phin tCr Id kdo thi quan hfi giira irng suit trung binh vd biln dgng trung binh dugc xem Id dan hfii vd hoan todn dfio Tuy nhifin,
M i l quan hfi nay b i t d i u tir khdi d i u dudng thing,
d i n gid trj Idn nhit (irng suit tdi hgn, ultimate strength) thi nhd han irng suit chdy Sau khi dgt dugc dllm tdi hgn, chang han trong viing sau gia trj tdi hgn, th) irng suit se giam (hinh 3)
Trang 4VbibiUaMcfilalUy
Vtoflif>taH'c*itf«
Hinh 3 Quan h^ irng suit trung binh vii b)£n dang
trung binh cua ph^n tfr ttadng thiTbng [4|
E)6i vdi cdc phin tir d gdc (hard comer element),
mii quan hfi giCra irng suit trung binh vd biln dgng
trung binh duge xem Id ddn hoi vd hodn todn deo
trfin d hai dgng keo vd nfin (nhu hinh 4)
Khi do nfii lue cua m i i phin tu kit d u dugc
xdc djnh bang irng suit trfin dien tich cOa nd (bao
tfin t i m dinh kem) vd ting cdc ndl lgc ndy chinh Id
tong Igc dpc tn,ic tren mdt d t ngang Ting nfii luc
hodc thay d i i bdi su di ehuyen ciia trgc tmng hda
Dieu do cho thay ring sg d n thiet phai xde dinh
vi tri hifin tgi cua trye trung hda, bang cdch tinh lgi
bien dgng, nfii lue vd tong nfii Igc tgi vi tri mdi, ldp
Igi cho d i n khi tong npi luc bdng khfing Mdt khi
Bdng 1 Ket qua thuc nghiem vd tinh
Hinh 4 Quan h$ ihig suat trung binh
vk hi^n d^ng trung binh cua phin tir iy g6c |4]
da bilt dugc vj tri mdi ciia trgc tnjng hda thi se xdc
djnh dugc chinh xdc phdn bo irng suit ciia cac phin tif k i t c l u TLP dd gid trj mfi men uon M, dol vdi
tnjc trung hda mdi dugc suy ra bdi dfi cong k, bang
cdch tong cdc md men ciia mfii phin tip ket d u
III KET QUA NGHIEN CI>U VA T H A O L U ^ N
1 Odnh gid do tin c|y ciia chuong trinh tinh (1$ ben chung
D l ddnh gid miPC dp tin cdy eua kit qua b'nh dp ben Chung tip chucmg trinh, chdng ta se so sdnh kit quS tinh ciia chuang trinh vdi kit qua thgc nghiem ed dugc
hpc khde duge ^ n g hgp d tdi lieu [4], [5\, [7], [10], [11]
todn do ben chung ciia 26 mau thi nghi|m
Dowing
1976
Recl<ling
1979
Nishihara
1983
Mansour1990
Dow 1991
Akhras 1998
Goido 2004
Gordo 2006
Gordo 2009
MN-2 (Sl
MH-A (S)
MN-10(S1
11
22
31
51
MST-3
MSB (S)
MSD (Sl
l«SC (Sl
Model II (HI
Fnoate (Sl
1/15-scale
M3-200
>I200
H300
4400
tofln phan M
2232
6209 318.2 282.0
257 9
496 9 808.3
1061 812.1
914.9
1066
2267
12790
1278 572.6
970
970
D$ b i n chung (M6 men tdri h^n M„) Kdt qua thgv nghifin
1517
4537 229.4 229.5 262.1
407.6 486.8 588.4
927
482
672 593.3
838 5
1113
863
1511 9780.7
1238 349.1
643 ,526
269
K 4 | qud Unh todn
1848
4361 287.3
237 8 217.6
404.2
524
777 5 659.2 694.4
593
1001 767.1
1456
1133 344.9
537
290
X 0.821
1.040 0.799
1 121 1.143
1.005 1.123
0.731 1.000 0.999 1.112
1.038 1.093
1.197 0.984 0.839
Trang 5"ll "1
- 1
Thdng qua viec ddnh gid hg so so sdnh X^
(X^ = K i t qud thg'c nghifim / Kit qud tinh todn cua
cua chuang trinh tinh Tip bdng 1 cd the de ddng xdc
djnh dugc (cho d 26 m i u thl nghifim) gid trj trung
binh ciia X^ = 1.026, dp Ifich cua X^ = 12.24% [5]
Nhu vdy, k i t qua cd dugc cOa chuang trinh tinh Id
chap nhfin Suae
2 Tinh dg b i n chung cua tdu hdng rot 2000 DWT
Hinh 5 the hifin mgt d t ngang giO'a cOa tdu
hang rdi 2000 DWT [2], trong dd x,: chieu ddy tdn vd
ngodi, x^: chilu ddy tdn vd trong, x^: chilu ddy song
chinh, X,: chieu ddy song phg x^: chieu cao sing
ehinh vd s6ng phg, x^: chieu ddy bdn bung xd dpc
mgn, x^: chieu cao ban bgng xd dpc mgn, x^: chilu
ddy ban cdnh xd dgc mgn x,: chilu cao bdn cdnh xd
E = 207000 MPa; He so Poisson n = 0.3; l>ng suit
chdysY = 2g7MPa
Mgt d t ngang di/gc phdn chia thanh 15 phin tip ddnh so tip 1 den 15 vdi vj tri va thdng so kich thudc cua cac phin t u nhu bdng 2
Bang 2 Bdng thdng s6 cdc phan t u cua mat cat ngang
XJ^
1 ^
Hinh S M^t cit ngang giiia cua \hu 20D0 DWT
Phin h> tho
1
2
3
4
5
6
7
8
9
1 0
11
12
1 3
1 4
15
Kich I h u ^ cda phin h>
T i m
1600*X1
1600*x1
1600*x1
1343.6*x1
1 3 3 8 " x ,
1 4 7 5 * x ,
1 6 0 0 ' x ,
1100*10
1900*10
1 6 0 0 * 8
1 6 0 0 * 8
1 6 0 0 * x ,
1 6 0 0 * X j
1 4 5 0 * x ,
1 1 0 0 * x ,
N ^ gia cu^ng
F B (Xg-X,-Xj)//X3
F B {Xg-X,.Xj)//x4
F B (Xg-x,-X5)/,*x4
F B (,x^-\-X.YZ'\
F B ( 9 0 0 - x , ) / 2 x 2
T V K A X
T x , * x ^ x , * x
FB 850*x,
1 4 0 0 * 1 0 / 1 0 0 * 1 0
7 4 0 0 * 8 / 1 0 0 * 1 0
T 4 0 0 * 8 / 1 0 0 * 1 0
F B (X5-x,-X2)/2*X3
F B {x,-x,-x,)/2*x^
F B (Xg-x,-x^)/2*x^
F B (X5-X,-X^V2*X^
Vj tri g6c phin tir Phirong y
0
1600
3 2 0 0
4 5 0 0
5 4 0 0
5 4 0 0
5 4 0 0
5 4 0 0
3 2 0 0
1 6 0 0
0
0
1 6 0 0
3 2 0 0
4 5 0 0
Phiromg z
0
0
0
0
7 5 0
2 2 0 0
3 7 0 0
5 4 0 0
5 4 2 6 5
5 4 2 9 8
6 4 3 1 7
7 5 0
7 5 0
7 5 0
7 5 0
Ghi chu
D o i x i j n g
G 6 o
D 6 i x i r n g
B o i xu'ng
Vdi m i i bp thdng so mdt d t ngang (x, - Xg),
chuang trinh tinh todn kilm tra gid trj momen u l n
tdi hgn M^ (hay dfi ben chung dudi tdc dgng ciia md
men u l n dpc trong hai ^ e u kifin tdu tren dinh sdng
vd day sdng) Hinh 6 la dfi thi cd dugc khi tir chuang
trinh vdi cdc thdng s l 12, 10, 12, 10, 750 8 250,
10, 100 mm, tuung ung vdi cdc biln tir x, d i n x^
vdi dp eong k cua tn,ie trung hda tgi vj tri mat edt
ngang dang xet Tip hinh 6, cd t h l xac djnh duac gia
tn md men uon Idn nhit ma vd tdu chju duge d hai trgng thdi tdu nim d dinh sdng (Hogging codition)
vd day sdng (Sagging codition) TCr gid trj nay so sdnh vdi gid tri rnd men uon theo quy phgm de bp thdng so mat eat ngang (x., - Xg) dang xdt cd thda man dilu kifin dfi bin chung hay khong
Trang 6M • E+11 H o g j i n g condition
M u = a 2 3 4 9 E * * 1 2 N m m
-20 -15 -10 -5 j
Sagging condition /
M u = 0.191OE+12 N m m / ^ ^
/ / /
/ k • E-07
5 lO 15 20
Hinh 6 B$ b^n chung ci
IV K t T LUAN
Nhu vdy, dga theo thufit todn cua phuang phdp
Smith, bdi bdo da xdy dung duge chuang trinh tinh
todn dfi bin chung (hoae dp ben tdi han ultimate
longitudinal strength) eiia tdu vo thfip d l phue vg
cho bdi todn toi uu hda k i t d u Dp tin edy ciia
chuang trinh da dugc minh chung qua ket qua so
sdnh vdi ede nghifin CLPU thgc nghifim da cfing b l
kn h i n g roi 2000 D W T
eho kit qud khd chinh xac vdi sai Ifich vdi thgc nghiem 12.24% Dong thdi dp dgng d l tinh toan dfi bin chung cho tdu hdng rdi 2000 DWT cua Nha mdy Ddng tdu Nha Trang Ro rdng vdi chuang trinh tinh ndy, cd t h l sir dyng d l tinh todn nhanh dp bin chung ciia tdu vd thdp vdi dif lifiu dau vdo dan gidn
Id kich thude hinh hgc cua mdt d t ngang vd thong s6 vat lifiu ca bdn
TAI LIEU THAM KHAO
Tieng Vif I
Pham Ba Linh, 2014 Nghien ciiu tfli iru hoa kit cSu tau vo thep sif dung k^t hop thuat toan chia doi va tim kidm tnjc Hep Tap
chi Khoa hpc - C6ng n ^ e Thuy san, S6 1 45-51
2 Nha may D6ng tau Nha Trang, 2001 H6 sa thiSt ki ky thuat tau hang 2000 DWT
3 Dang kiem Vi?t Nam, 1997 Quy ph^m phSn cSp va dong tau hiSn vo th6p TCVN 6952:1997 Ha N^i
Tieng Anh
4 Caldwell, J B., 1965 Ultimate Longitudinal Strength Transaction of RINA, 1965 107: p 411-430
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