# Buckling cylindrical shell axial with shell elements

**URL:** <https://calculix.discourse.group/t/buckling-cylindrical-shell-axial-with-shell-elements/2813>\
**Category:** Uncategorized\
**Created:** [July 21, 2025, 7:26pm UTC](https://calculix.discourse.group/t/buckling-cylindrical-shell-axial-with-shell-elements/2813 "2025-07-21T19:26:59Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![dichtstoff](https://avatars.discourse-cdn.com/v4/letter/d/dec6dc/32.png) [@dichtstoff](https://calculix.discourse.group/u/dichtstoff)\
**Post date:** [July 21, 2025, 7:26pm UTC](https://calculix.discourse.group/t/buckling-cylindrical-shell-axial-with-shell-elements/2813/1 "2025-07-21T19:26:59Z")

</div>

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

```auto
# 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

```auto
**** 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

```

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 ![grafik](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/c/c8edecc718a19c3d49b4a059f9085ca7d8f15a7c.png)

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 ![grafik](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/f/f758b4b0ed7d20a7ff9804a3d89d6e996f3fa87c.png)

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