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HNG DN S DNG ABAQUS/CAE (COMPUTER AID
ENGINEERING) C BN Bi ton:
F = 50N
2cm
L = 1m
15cm
Vt liu thp: E = 200.109 Pa, G = 80.109 Pa, S dng ABAQUS tnh:
a) Phn b ng sut, bin dng, chuyn v
0.3
b) Tm tn s dao ng t nhin fn, mode dao ng c) Nghin cu nh hng ca
vic chia li
CCH TIN HNH
Bc 1: To m hnh, trong bc ny cc bn s c tip xc vi cc cng c
modeling
ca Abaqus, c th l 2D hoc 3D ty theo yu cu Bc 2: Xc nh vt liu v
section hoc profile, profile dng cho model 2D, section dng cho
model 3D
Bc 3: To mt b lp hon chnh (assembly) Bc 4: Xc nh cc bc phn tch v
yu cu xut kt qu Bc 5: Xc nh iu kin bin v t ti Bc 6: Chia vng trong
mu hin thi ca part( ch cn khi c yu cu c bit, s c
trong nhng bi ton phc tp hn) Bc 7: Chia li cho assembly Bc 8 :
To, chy v quan st mt tc v
Bc 9: Quan st kt qu
Bc 10: Xut kt qu ra dng vn bn
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BC 1
Bc u tin ca mt bi ton bao gi cng l phi to mt m hnh, to mt m hnh
nh
trong hnh v, ch y l vt th 3 chiu nn ta s v theo cch extrude mt
ct vi su bng chiu di dm.
Khi ng chng trnh Abaqus, chn tab create model database s xut hin
module to m hnh n (part) vi cc cng c ca mt chong trnh Cad v thit k
da theo tham s (parameter). double-click vo mc part trong model
1,
hp thoi create part xut hin, t tn l canbeam (cantilever beam) v
chn cc thng s mc nh theo hnh sau:
Gii thch: D l cho m hnh 3D, kiu deformable c th bin dng c,
phn
base feature th chn solid extrude to 1 khi rn bng cch y 1 mt ct
no . Approximate size th chn nh th ny: chia li (grid) trong mi trng
v s chia lm sao cho thun li trong qu trnh v, do chn chia li
phi da theo m hnh cn to, v m hnh cng phc tp th chia li phi nh d
dng bt im trong khi modeling, ti chn 2 v chiu di model l 1m v khng
chi tit phc tp, ch l th nguyn dng trong Abaqus l theo SI.
Bm continue ra khi hp thoi create part.
Khng gian to m hnh hin ra vi mt li tha d quan st. Trc ht
v mt mt ct ch nht kch thc 15 2 cm. Chn nt v hnh ch nht, sau v mt
hnh xung quanh gc ta ca li quan st 2 hnh bn di, sau
khi v hnh ch nht nhn ESC thot khi lnh v hnh ch nht.(ch : v i hnh
ch nht ko cn quan tm kch thc).
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Hnh ch nht va v cha c kch thc, by gi ta s dng tnh nng tham s ca
Abaqus hiu chnh kch thc.
Hnh trn ch mt cm tnh nng ca model 2D, theo th t t tri qua phi,
trn xung di l (t ng rng buc, rng buc, t ng thm kch thc, thm kch
thc, sa kch thc v qun l tham s). Chn nt thm kch thc thm 2 kch
thc cho hnh ch nht.
Sau khi click vo nt thm kch thc, click chn cnh tri nh hnh v, sau
r chut ra ngoi v chn ch t kch thc, click ln na t kch thc, di
khng gian v l 1 thanh hin trng, yu cu nhp kch thc, ta nhp kch
thc theo th nguyn (m) l 0.02m v cnh cn li l 0.15m. sau khi t 2 kch
thc
dng nt scroll ca chut phng to thu nh khng gian nhn, sao cho c
hnh nh
sau:
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Ch : ta nhn vo 4 gc ca hnh ch nht th thy 4 k hiu vung gc chng
t
hnh ch nht ny c rng buc y (full constraint) v ta dng lnhh v hnh
ch nht nn Abaqus t ng t rng buc, nu ta dng lnh v line th khi to hnh
ch nht(cha tht chnh xc) th phi p rng buc cho n(dng nt t rng buc v d
nh cnh song song cnh ng cng ngang, tip tuyn). Nu ta t thiu hoc d
rng buc cho mt phc tho(sketch) 2D th Abaqus s bo li v khng cho qua
bc to part. Sau khi y rng buc th click done di thanh tnh trng thot
khi ch phc tho. Hp thoi edit base extrusion xut hin, in thng s nh
hnh v:
Depth =1 ch chiu su extrude l 1 mt, khi dng lnh ny tao s to ra c
cantilever beam c dng nh yu cu. ch thch thm: include twist l
extrude 1 phc tho theo bc xon, v d 1 im quay 1 vng th khong cc gia
im trc v sau khi quay 1 vng l thng s ny, include draft l gc vut khi
extrude to vt th c profile thay i, ta khng cn nn cc thng s ny l 0.
Nhn ok s c c m hnh mu xm nh sau:
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trc ta 1 2 3 trong khng gian v l h trc ton cc (global) trong mi
part u c mt h trc xyz cc b (local).
BC 2 : XC NH VT LIU V TNH CHT MT CT gn vt liu ta double-click vo
phn material trong cy model, trong
hp thoi edit material ta t tn cho vt liu, trng hp ny l thp, ri
chn cc mc nh hnh sau(vt liu n hi):
Sau ta in thng s module n hi v h s poisson vo. Chn loi vt liu ng
hng l isotropic. Cc thng s cn li gi mc nh. Click ok, quan st vo phn
material, nu c s 1 pha sau th vt liu c gn.
Xc nh tnh cht mt ct: define section Double-click vo mc sections,
xut hin hp thoi create sections xut hin. Nhc li l trong thit k m
hnh 3D th xc nh tnh cht section, cn trong 2D th to profile. t tn l
canbeamsection, chn vt liu rn ng nht (solidhomogeneous) nh hnh di
y, bm continue qua phn edit section.
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Chn vt liu va xc lp l thp, chp nhn gi tr 1 cho plane
stress/strain thickness. Click ok hon tt. Sau khi xc nh tnh cht mt
ct th ta phi ch nh n vo trong part nh th no Abaqus hiu m phn tch(
assign sections properties)
M cy model nh hnh sau s thy c tnh nng ch nh mt
ct(partscanbeam)
Double-click vo Section Assignments chuyn sang khung v,
Abaqus yu cu chn vng ch nh mt ct, v bi ny ta cha to
partitions(phn vng) cho part nn ch cn click vo part l chn ton b
part, khi part c t ni bng khung dy th nhn nt chut gia hoc nhn done
di khung v kt thc vic chn, hp thoi
Edit Section Assignment xut hin,chn canbeamsection va to, click
OK hon tt vic ch nh section, part s hin th phn c ch nh section bng
mu xanh l.
BC 3: TO B LP( CREATE AN ASSEMBLY) Mt b lp ch ng cc phn t hnh hc
bao gm cc m hnh phn t hu hn, mi m hnh ca ABAQUS/CAE cha mt b lp n,
nhng khi to part th n cha c, v vy ta phi to mt mu mi (instance) ca
part trong module assembly s dng cho m hnh.
Trc ht l to Instance ca mt part: M rng mc Assembly trong model
tree, double-click vo instances nh trong hnh v to instances.
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Trong hp thoi create instance chn part canbeam, c 2 ty chn l
Dependent v Independent, Dependent l chia li ngay trn part,
cn Independent l chia li trn instances ca part, mt part c th c
nhiu instance, chn auto offset from orther other instance to thm
instance song song vi instance c, v sao c instance c lp v ph thuc?
v trong bi ton n gin t chi tit th ta ch cn chia li part lun, trong
nhng bi ton nhiu chi tit, phn c lp s cho php ta chia li khc nhau vi
mi instance, nu chia li lun c part th tt c cc instance u ging nhau.
Vy trong bi ny ta chn nh hnh v:
Click OK Abaqus s to instanse cho part, mu ca instance l mu xanh
dng, rng khi to ra mt instance no th n u c h ta
a phng xyz, trong trng hp ny s trng phng vi h ton cc.
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BC 4: CC BC PHN TCH V YU CU XUT KT QU
Trong phn ny bn s phi xc nh bc phn tch. V s tng tc, ti lc v iu
kin bin c th nh hng ln nhau, do ta phi xc nh
bc phn tch trc cc iu kin ny. Trong bi ny ta xc nh bc single
static v general, thm na l yu cu xut kt qu ca vic phn tch, kt qu
xut ra di dng output database (*.odb) file.
Xc nh bc: trong model tree double-click vo steps, hp thoi create
step xut hin, t tn bc l canbeamload, chp nhn procedure type l
General. Trong mc scroll th chn Static, General. Click OK.
Edit step: hp thoi edit step xut hin, tab Basic l m u tin, in
thng tin m t Description l : t ti 50 N ti mi , chp nhn gi tr mc nh
cn li trong tab basic, chuyn qua tab incrementation, ta thy trong
tab ny c phn chn s gia ti a l 100 (gi mc nh), cn trong phn kch thc
s gia c 3 mc, bt u, nh nht, v ln nht, t ng Abaqus s chn s cc thng s
ny da vo time period trong tab basic, initial v maximum lun bng
time period, cn minimum l 1E-5, ta c th thay i thng s initial l
0.1. Ok to bc.
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To thm bc tn s, cch lm nh sau: double-click li mc step, sa tn l
tn s, trong procedure type chn linear perturbation, chn frequency
trong bn di v click continue:
Trong hp thoi edit step, ghi tn m t trong description la tan so,
ta thy Nlgeom off ngha l b qua bin dng ln, trong eigensolver c 3 lc
chn,
lanczos, subspace v AMS, thng dng 2 phng php u, trong trng hp m
hnh tnh ton c nhiu bc t do, ngha l s c nhiu mode dao ng ring ng vi
cc tn s, subspace cho kt qu nhanh v tt trong trng hp t mode ring(nh
hn 20) v ngc li. Trong bi ny mode dao ng khng nhiu do chn subspace,
khi chn subspace th tab th 2 cho phng php lanczos m i, chn tr ring
l 6 v vector trn mt chu k lp l 16(cha hiu r), OK kt thc bc tn
s.
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v sau cng chng ta s dng module visualization quan st kt qu nn cn
phi xc nh nhng d liu cn xut ra file c s d liu phc v cho mc ch ,
thng thng th Abaqus s dng trng d liu trc p dng, nhng ta nn t to v
xo trng d liu xut c i (history output request).
Cch xc nh trng d liu xut ra file *.odb Trong model tree click
phi vo Field Output Requests v chn manager trong context menu (ch :
c 2 trng output request ng vi 2 bc canbeamload v tan so va to trn)
Hp thoi Field Output Requests Manager xut hin c dng nh sau:
Chn vo created trong phn bc canbeamload, click edit. Trong hp
thoi Edit Field Output Request s cho chn cc kt qu cn tnh, ta quan
st mt phn trong hp thoi:
Ta thy c 5 la chn c nh du, v ta ch mun tm ng sut v chuyn
v, do b chn 3 thng s cn li (toggle off strains, forces/reactions
v contact)
2 mc cn li chp nhn mc nh nh hnh sau:
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Click Ok quay li hp thoi Edit Field Output Request : Tip tc chn
created trong bc tan so, click edit:
Chp nhn gi tr mc nh, v tn s ch thay i trong dao ng chuyn v, do
Abaqus ch c 1 la chn khi ta click edit. Click ok sau click Dismiss
thot khi hp thoi. Ch : Dissmis v Cancel, cancel l b mt tc v, cn
Dissmis l thot khi hp thoi khi chp nhn tc v! Di Field Output
Request l history output request, ta nn xa phn ny trc khi i tip khi
thy n c gi tr 1 phi sau ( ni ti sao), tin hnh:
Click phi, chn manager, hp thoi edit xut hin, chn nt Delete ,
chn
yes, ri click Dismiss thot
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BC 5: T IU KIN BIN V T TI Trong bi ny th ta thy bn tri canbeam l
ngm cht, bn phi th chu mt ti tp trung, vy iu kin bin s c t ti bin
tri v ti lc t bn phi.
t iu kin bin: Double-click vo BCs trong model tree, hp thoi
Create Boundary Condition xut hin:
t tn l Ngam bien trai, chn bc l initial cho iu kin ban u, nhng
trong a s bi ton iu kin bin chn l canbeamload cng nh nhau v tc dng
ca cc bc khng nh hng iu kin bin. Cc thng s cn li chn theo hnh trn.
Click continue sang ch chn vng gn iu kin bin. R chut vo vng m hnh v
chn mt tri, gn gc ta ton cc. Khi thy mt bn tri c mu th n c chn, v
sau nhn Done .
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Khi click done th hp thoi Edit iu kin bin hin ra, chn rng buc 6
bc t do l encastre, Ok gn iu kin bin.
Khi c iu kin bin th Abaqus k hiu ging hnh sau:
d dng xem m hnh th chn nt cng c pan v rotate trn
toolbar.
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t ti:
Double-click vo Loads trong model tree, hp thai create load xut
hin
t tn v chn bc nh hnh v, xut hin khung chn chng loi, chn
mechanical v quan st cc ty chn bn tri.
Vi bi ton 2D th chn ti tp trung mt cch d dng, vi m hnh 3D th ta
hnh dung l lc t phi tri u theo phng ton cc 1 hay phng x ca m hnh,
thc cht lc ny ging nh 1 lc ct ngay ti mi dm, gi tr m v hng xung so
vi phng y. Cc bn c th th tng dng xem cho hiu thm cc cch t ti, Lm nh
sau: Trong phn chn loi ti, chn surface traction, click continue. Di
vng v yu cu chn mt, lc ny ta cn phi quay m hnh d dng chn mt phng bn
phi, xong ri chn, khi thy mt phng t th click Done qua bc k tip
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Hp thoi edit load hin ra
Chn mc nh phn b u v ct mt bng lc
ct(distribution=uniform,traction=shear) ,trong phn Direction l ch
phng ca lc, chn nh sau:
Chn ch bt nt to phng, khi chn global v click edit th
Abaqus chuyn qua mn hnh ca model cho php chn phng vector lc. chn
2 nt nh ch dn sau, theo th t trn xung di.
Theo hnh trn th phng vector l (0,-1,0), ngc chiu phng y.
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Sau khi nhp phng vector, quay li hp thoi edit load, nhp gi
tr
lc vo phn Magnitude=50. ging hnh di, Ok hon tt t ti.
Khi thy lc t nh hnh sau l t yu cu
BC 6: CHIA VNG Hin bi ny khng cn chia vng.
BC 7: CHIA LI Trc khi tin hnh ta ni s v vn chia li, chia li mt
model c nhiu cch chia v ty vo vt liu m ta c cc dng phn t trong
Abaqus, nhng c bn v chia li th nh th ny: Xem hnh di y
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Cc phn t dng chia li vi 1D,2D v 3D, ta ch yu s dng 2D v 3D, chng
c phn loi theo tuyn tnh hay bc 2, v trong mi loi vi 2D th c phn t 3
nt v 4 nt, trong 3D th c t din, lc v ng din. cch chia li phc tp
theo tng model, v th Abaqus cung cp 3 phng php chia li l theo kt
cu(structured), cch t do(free) v cch qut(swept). Linh hot trong cch
to v t nhiu c
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kinh nghim th mi c th s dng phng n chia li hiu qu
nht. Bi ny ta chia li n gin theo kt cu v model khng phc tp.
Trong model tree m rng partsri canbeam v double-click vo mesh,
khi ta chuyn sang module meshing.
To ht ging chia li Abaqus cung cp cng c ht ging(seed) lm c s
chia li, ta lm nh sau: Vo menu Seed chn part Hp thoi global seed
hin ra, chn gi tr approximate global size nh sau: V d: chiu di
thanh l 1 m, nu chn approximate global size l 0.1 th ton b chiu di
thanh chia lm 10 ph, mi phn l 10cm. nu chn l 0.02 th s c 50 phn mi
phn l 2cm, bng chiu rng mt ct, nh vy s tt hn. Vy ta chn nh hnh v,
ok hon tt seed part.
Trn menu mesh chn element type, hp thoi xut hin:chn nh hnh
sau:
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V ti khng i nn chn Standard, ng sut cho m hnh 3D, phn t hnh hc l
tuyn tnh (ging vin gch), di cui hp thoi cho ta k hiu ca loi phn t l
C3D8R. Chp nhn cc mc nh, OK. v ta ch c mt part khng phn vng nn ta
ch cn click chn ton b part. Chn meshpart trong menu, Yes l hon tt
chia li.
BC 8: TO, CHY V KIM TRA 1 TC V Trc khi tip tc ta nn i tn model-1
trong model tree thnh Elastic, dng chut phirename.
To mt Job Double-click mc Jobs trong model tree, t tn l canbeam
v chp nhn model va t tn l Elastic, click continue.
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Hp thoi edit job hin ra, chn mt cu m t, v d nh trong hnh, chp
nhn mc nh v OK.
Chy tc v Trong mc jobs model tree, click phi vo tc v canbeam va
to, chn submit.
Abaqus s hin bng thng bo v trng output trc ko cn, ta nhn yes v
ta ch ng to iu ny.
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i mt lc th Abaqus thng bo l Abort!,
V y l m hnh 3D c tnh cht mass, do ta phi khai bo tnh cht khi cho
vt liu Quay li mc materials trong model tree, click phi vo thep v
chn edit
Chn tab general, chn density
in thng s khi lng ring cho vt liu thp l 7800kg,OK hon tt
Sau ta Submit li Jobs canbeam, thng bo Overwrite ghi
li ci hng trc , chn ok v chn yes trong thng bo history output.
Ln ny sau job canbeam s c ch complete.
Kim tra li Click phi vo jobs canbeam v chn monitor, xut hin hp
thoi sau:
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i khi c cnh bo tronh warning nhng c th ko quan trng. Click
Dismiss chp nhn.
BC 9: QUAN ST KT QU C 2 cch coi kt qu: 1: l chn visualization
trong mudule nh hnh v.
Sau vo fileopen d liu dng canbeam.odb 2: click phi vo job
canbeam chn result, th cch ny nhanh hn, Abaqus t ng m
canbeam.odb
Sau cng s c mn hnh ny
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quan st theo ng mt phng th chn viewtool box, Sau chn view theo
mt phng 2 3
ta cn quan st cc mode dao ng trc, chn nh sau:
Xut hin hp thoi:
C 6 mode dao ng vi tn s xc nh, ta s xem tng dng bng cch chn tng
ci, khi chn tng mode th s ra ngoi quan st, chn cc cng c nh sau(dng
tool tip bit tnh nng) v.
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Ta c th v lc bin dng v cha bit dng bng cch dng chc nng xem cng
lc:
Chn thm v contour c 6 hnh vi 6 mode sau:
Mode 1
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Mode 2
Mode 3
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Mode 4
Mode 5
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Mode 6
SAU Y L CCH XEM CHUYN V DI TI 50N
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Chn ti lc trong hp thoi step/ frame , ng vi mi step th c
mt chuyn v, nhng trong Abaqus s t ng hiu chnh scale factor nn ta
ko nhn thy r khc bit, thy r khc bit th lm nh sau: Vo menu option
common:
Hp thoi xut hin:
Chn nh hnh v, thngh s value cc bn t thay i cho ph hp, tr li mc
nh th chn defaults.
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chuyn v sau thi gian 1s
BC 10: XUT KT QU RA DNG FILE TEXT Chn report field output
Hp thoi xut hin
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Nt step/ frame cho php chn li cc steps xut, trng hp ny ta chn
step 6
l 1s. Trong phn position cho php ta chn cc kiu xut ra.
Ta chn unique nodal c th xut ng sut v chuyn v Bung 2 nt tam gic
chn cc yu cu cn xut, chn Mises, S11, S22, S33, S12, S13, S23 cho
phn ng sut. Chn U1, U2, U3 cho phn chuyn v. Chuyn qua tab setup t
tn cho file report (*.rpt)
Nhn apply th Abaqus s to ra file canbeam.rpt trong th mc lm vic
(th mc temp, thng cng cp vi Abaqus). Xem v d kt qu:
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Field Output Report, written Wed Oct 11 10:24:49 2006
Source 1 ---------
ODB: D:/temp/canbeam.odb Step: canbeamload Frame: Increment 6:
Step Time = 1.000
Loc 1 : Nodal values from source 1
Output sorted by column "Node Label".
Field Output reported at nodes for part: CANBEAM-1
Computation algorithm: EXTRAPOLATE_COMPUTE_AVERAGE Averaged at
nodes Averaging regions: ODB_REGIONS
Node U.U1 U.U2 U.U3 S.Mises S.S11 S.S22 S.S33 S.S12 S.S13 S.S23
Label @Loc 1 @Loc 1 @Loc 1 @Loc 1 @Loc 1 @Loc 1 @Loc 1 @Loc 1 @Loc
1 @Loc 1
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1 0. 0. 0. 86.6025 -122.719E-12 -197.451E-12 -6.05368E-12
-11.0298E-09 12.2168E-12 50. 2 0. 0. 0. 86.6025 -122.719E-12
-197.451E-12 -6.05368E-12 -11.0298E-09 12.2168E-12 50. 3 2.3231E-21
-136.521E-09 136.508E-09 86.6025 -888.928E-15 6.30919E-12
4.27306E-12 210.74E-12 4.07227E-12 50. 4 -2.3917E-21 -136.521E-09
-136.508E-09 86.6025 -888.928E-15 6.30919E-12 4.27306E-12
210.74E-12 4.07227E-12 50. 5 -5.46609E-21 -543.302E-09 270.259E-09
86.6025 -11.143E-12 -22.8099E-12 5.696E-12 -374.649E-12 2.03614E-12
50. 6 5.14066E-21 -543.302E-09 -270.259E-09 86.6025 -11.143E-12
-22.8099E-12 5.696E-12 -374.649E-12 2.03614E-12 50. 7 5.17488E-21
-1.21482E-06 401.252E-09 86.6025 -7.22045E-12 -17.6383E-12
19.0121E-12 480.529E-12 4.07227E-12 50. 8 -5.8281E-21 -1.21482E-06
-401.252E-09 86.6025 -7.22045E-12 -17.6383E-12 19.0121E-12
480.529E-12 4.07227E-12 50.
9 -10.6673E-21 -2.14557E-06 529.487E-09 86.6025 -66.7977E-12
-150.796E-12 -12.3385E-12 -716.72E-12 4.07227E-12 50.
10 9.37742E-21 -2.14557E-06 -529.487E-09 86.6025 -66.7977E-12
-150.796E-12 -12.3385E-12 -716.72E-12 4.07227E-12 50.
11 9.81552E-21 -3.33004E-06 654.964E-09 86.6025 5.68896E-12
-23.159E-12 58.2865E-12 1.10766E-09 -4.07227E-12 50.
12 -11.6273E-21 -3.33004E-06 -654.964E-09 86.6025 5.68896E-12
-23.159E-12 58.2865E-12 1.10766E-09 -4.07227E-12 50.
. .
C tt c 918 nt trong ba ton ny.
The end