

December 2, 2019 at 10:46 pmAetasSubscriber
Hi,
I am trying to make a macro for an evaluation of deformation on cantiliver beam, which has an I profile and is loaded with torque moment. I am tasked to use shell elements. However when I use them, total deformation of this beam is something about 1.3 meters, while the beam is only one meter long. So it is totally off. It seems to me that geometry and mesh is correct and I can't find error in definition of constraints (in cantiliver end there is no displacement and rotation) and loads should be correct as well.
When I used beam elements I've come to total deformation of 7e4 mm.
Can anyone help me please?
Thank you in advance.
!Macro file
!Example: Optimalization of beam parameters
!Date: 02/12/2019
!version 1
finish
/clear,nostart
!Definition of model parameters [dimensions unit: mm]
H = 20
t = 2
L = 1000
Mk = 1e6 ![N*mm]
!Definition of material
/prep7
mptemp,1,0
mpdata,ex,1,,2.1e5
mpdata,prxy,1,,0.3
!Definition of elements
!*
et,1,shell181
!*
!Definition of thickness
sect,1,shell
secdata, t,1,0.0,5
secoffset,MID
!Definition of geometry
BLOCK,H/4,0,0,L,H/2,H/2 !Left half of beam
BLOCK,0,H/4,0,L,H/2,H/2 !Right half of beam
!Adding middle part together
LSEL,NONE
LSEL,S,,,3,
LSEL,A,,,13,
NUMMRG,ALL
LSEL,NONE
LSEL,S,,,10
LSEL,A,,,21
NUMMRG,ALL
LSEL,NONE
LSEL,S,,,6
LSEL,A,,,20
NUMMRG,ALL
LSEL,NONE
LSEL,A,,,11
LSEL,A,,,24
NUMMRG,ALL
LSEL,ALL
ASEL,NONE
ASEL,A,,,6
ASEL,A,,,11
NUMMRG,ALL
ASEL,ALL
!Set element size of crosssection to value of 1 mm
LSEL,NONE
LSEL,A,,,2
LSEL,A,,,4
LSEL,A,,,5
LSEL,A,,,7
LSEL,A,,,10
LSEL,A,,,11
LSEL,A,,,14
LSEL,A,,,16
LSEL,A,,,17
LSEL,A,,,19
CM,_Y,LINE
CMSEL,,_Y
!*
LESIZE,_Y,0.5, , , , , , ,1
!*
LSEL,ALL
!Set element size of beam to value of 5mm
LSEL,NONE
LSEL,A,,,1
LSEL,A,,,3
LSEL,A,,,6
LSEL,A,,,8
LSEL,A,,,15
LSEL,A,,,18
CM,_Y1,LINE
CMSEL,,_Y1
!*
LESIZE,_Y1,5, , , , , , ,1
!*
LSEL,ALL
!Creating mapped mesh
ASEL,NONE
ASEL,A,,,1
ASEL,A,,,2
ASEL,A,,,6
ASEL,A,,,7
ASEL,A,,,8
CM,_Y,AREA
CHKMSH,'AREA'
CMSEL,S,_Y
!*
AMESH,_Y
!Definition of constrains and loads
LSEL,NONE
LSEL,A,,,4
LSEL,A,,,5
LSEL,A,,,10
LSEL,A,,,16
LSEL,A,,,17
DL,ALL, ,ALL,
LSEL,ALL
KSEL,NONE
KSEL,A,,,1
KSEL,A,,,3
KSEL,A,,,11
FK,ALL,FX,Mk/(H*3)
KSEL,NONE
KSEL,A,,,7
KSEL,A,,,8
KSEL,A,,,15
FK,ALL,FX,Mk/(H*3)
ALLSEL,ALL
!solution of linear structural problem
/solu
solve

December 5, 2019 at 1:44 pmAniketAnsys Employee
Is there any specific reason for using Shell elements instead of Beam elements? Let us know!
Aniket
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