distribution between fem and ftool

[mir]

Hi.
fem analysis and ftool analysis give me very different results as you can see from the attached file ... which can depend on?

ie for the fem is I have a ridiculous shift of 0.25 mm while for ftool coming to a shift of 9 mm!


Thank you.
♪

nb: both beams are 1.07 m long and both have a central load of 16000 n. ... both software use an elastic module of 206000 n/mm2 and a poisson of 0.3.

 

[cacciatorino]

nb: both beams are 1.07 m long and both have a central load of 16000 n. ... both software use an elastic module of 206000 n/mm2 and a poisson of 0.3.

Probably different conditions of constraint, and then in fem calculations the way mesh is very important.

 

[Fulvio Romano]

140mm x 1070mm... I would say that de Saint Venant's theory should adequately describe the problem. So the accounts made by ftool are right.

fem simulation is also influenced by that processing at the ends. Anyway, from the picture, I think I see a strange deformation. there is no horizontal tangency to the constraints, or at least it is very short, then there is a piece of beam straight and then the central part very curved. means that the rigidity of the beam is not constant. . .

there must be some problem with the mathematical rigidity of mesh. Can you post the mesh, and also the efforts to von mises, so let's see if they have strange ways?

also can you post a deformed view in the deformation plan and not in assonometry?

 

[Onda]

is it not that in ftool you have 1600kn=1600000n while in the fem you have 16000n i.e. 1/100 of the load?
Moreover it seems that in the fem you have bound only the soul and not the piattabanda (maybe mistaken) creating a way between a hinge and an ink

 

[mir]

Yes. the beam is shaped to fit perpendicularly into another ipe 140 ... and I have bound only the soul and not the piattabande.

tomorrow I place the resolutions of von mises... However, they are 9 mm of difference! and this also implies that they are, for ftool, in plastic zone (about 190 n/mm2)

ftool are 1600 kn
in fem 16000 n

 

[Onda]

I don't understand you.
On one side you put 100 times the load. as you are in the linear field you have 25 mm in fem and 9mm in ftool.
The difference is due to the type of bond in the fem, which does not bind the plague is not a perfect ink.
It seems very clear to me.

The plastic zone doesn't exist in the analyses you've done. both software are linear.

 

[Fulvio Romano]

On one side you put 100 times the load. as you are in the linear field you have 25 mm in fem and 9mm in ftool.

I don't understand this part. on ftool leggo 1600kn (160 tons), while on the fem the bottom scale is 4000, what does it mean? If the force was 1600 n would be green and not red, while 16000 is out of scale... what strength did you apply? Is it a force or a pressure?

The difference is due to the type of bond in the fem, which does not bind the plague is not a perfect ink.

as I said.

The plastic zone doesn't exist in the analyses you've done. both software are linear.

I don't think that in the fem the analysis is linear, but the material itself and hyperelastic. therefore not linearity of constitutive bond, plasticizations etc. are not contemplated by either of the two software.

 

[mir]

1. great transformation 16000 n = 1600 kn .... blame of Wednesday evening!
2. with plastic deformation I looked at the sigma of the efforts... not that it was understood from the fem.

what to say.... thanks above all to fulvio

♪

ps: I uploaded the file with new processing if you have curiosity to view everything.

 

[mir]

I ask myself another question (I think more oriented to those who use the fems) ... why do I not see any moment in the fem? all the moments I can choose to see (inside, applied, reaction) give me null value everywhere.

depends on the constraints?

 

[pollo]

put so it is difficult to tell you something. But are you sure you have used elements that accept moments?

 

[mir]

elements that accept moments.... I didn't know about that... they're just 3d bodies (traves specifically) ...

 

[pollo]

bhe, if you use auction elements with hinges at the ends it is difficult to transmit moments.
Hi.