hello,
i made an example for buckling of cylindrical shell under axial compression
with S8 shell elements. For boundary i need to add spring elements.
if someone has a better solution, please let me know.
maybe i can fix one example with solid elements.
wbr
create-cylinder-shell-S8-truss.fbd
# written by dichtstoff
# buckling cylinder shell
# raduius of cylinder
valu rdist 3000
# 105 / 90 / 75 / *60* / 45 / 30 / 15
# amount of element for circumference
# U=2*pi*r = 2*pi*3000 = 18850 / 3 / 60 = 105
valu lidivaoefc 105
# height of cylinder
valu hdist 6860
# amount of element for height
# n = 6860 / 60 = 114
valu lidivaoefh 114
PNT ! rdist
PNT ! 0
seta D001 p D001
swep D001 D001 rot z 120 1
seta L001 l L001
copy L001 L002 rot z 120
copy L002 L003 rot z 120
merg p all
seta basis l L001 L002 L003
swep basis shaft tra 0 0 hdist 1
seta circumference L001 L002 L003 L004 L005 L006
seta height L008 L009 L00A
div circumference mult lidivaoefc
div height mult lidivaoefh
flip all
div all mult 2
elty all QU8
mesh all
seta truss p D003 D008 D009
swep truss truss tra 0 0 -500 1
seta truss l L00B L00C L00D
elty truss BE2
mesh truss
merg p all
merg n all
seta nodes n all
enq nodes boundary-bottom cz _ _ 0 1
enq nodes boundary-top cz _ _ 6860 1
enq nodes fix-z cz _ _ -500 1
prnt se
plot pa all
plus la all
plot e all
view elem
plus n boundary-bottom b
plus n boundary-top m
plus n fix-z r
send all abq
send boundary-bottom abq nam
send boundary-top abq nam
send fix-z abq nam
cylinder-buckling-shell-S8-truss.inp
**** written by dichtstoff
**** buckling of cylindrical shell under axial compression
**** sigma critical according Theory of elastic stability
**** by S. Timoshenko 1936
**** sigma critical = E*t/[r(3(1-v^2))]
**** E = Young's modulus = 210000
**** v = Poisson's ratio = 0.30
**** t = thickness of the shell = 5.00
**** r = radius of cylinder = 3000
**** h = height of cylinder = 6860
**** sigma cricital = 212.0
**** stress = 2*pi*r*t = 94248 = 94248
*HEADING
Model: buckling cylindrical shell axial compression
*INCLUDE, INPUT=all.msh
*INCLUDE, INPUT=boundary-bottom.nam
*INCLUDE, INPUT=boundary-top.nam
*INCLUDE, INPUT=fix-z.nam
*TRANSFORM, TYPE=C, NSET=Nall
0,0,0,0,0,1
*MATERIAL, NAME=steel
*ELASTIC
210000, 0.30
*DENSITY
7.85e-9
*SHELL SECTION, ELSET=Eall, MATERIAL=steel
5
**** change all.msh
**** *ELEMENT, TYPE=B31, ELSET=Eall
**** with
**** *ELEMENT, TYPE=T3D2, ELSET=Etruss
**** change all. msh
*SOLID SECTION,ELSET=Etruss,MATERIAL=steel
1
*STEP
***STATIC, SOLVER=SPOOLES
*BUCKLE, SOLVER=SPOOLES
8, 1.0e-6
*BOUNDARY
Nboundary-bottom,1,2,0
Nboundary-bottom,4,6,0
Nboundary-top ,1,2,0
Nboundary-top ,4,6,0
Nfix-z ,1,3,0
*CLOAD
**** 94248/630=150
Nboundary-top ,3,-150
Nboundary-bottom,3,+150
*NODE FILE,
U
*EL FILE, OUTPUT=2D
S
*NODE PRINT, NSET=Nboundary-top, TOTALS=ONLY
RF
*NODE PRINT, NSET=Nfix-z, TOTALS=ONLY
RF
*NODE PRINT, NSET=Nall, TOTALS=ONLY
RF
*END STEP
