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[Aetas]

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 7e-4 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 cross-section 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

 

[Aniket]

Is there any specific reason for using Shell elements instead of Beam elements? Let us know!

-Aniket

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