nyprohutni.cz/deleni-ocelovych-svitku]]>

pity you could build a plate on the rolls of a rolling mill before it is cut and coiled

Yep this is the kind of stuff, but a lot more thinner haha.

]]>Hi,

Im not trying to build anything

pity you could build a plate on the rolls of a rolling mill before it is cut and coiled

(in the pic the scale factor is multiplied "x 50")

]]>Im not trying to build anything, just understanding a case of a belt under its own weight. I'll take a look at the elastic catenary equation to see if it match the order of magnitude.

Thanks

Edit: The nodal force give the same result, so I think you were right Jonas.

]]>STAT_NON_LINE is the way to go then, or do you have another, easier idea, M. Aubry?

oh yes i have an idea!

as an engineer i would never build something with these figures after a quick analytical approach

that is all

the result is so far out that a STAT_NON_LINE will not proove the structure to be feasible

]]>hello all

i wonder what you guys find strange in here

a MECA_STATIQUE analysis gives exactly the same results as a quick analytic with beam theorythe contrary would be strange

jean pierre aubry

You are right of course. I rarely have to use the analytical approach, so when it is a good idea to use it, I don't think about it at all ... So Beam-theory and MECA_STATIQUE give results, that don't match reality... STAT_NON_LINE is the way to go then, or do you have another, easier idea, M. Aubry?

]]>i wonder what you guys find strange in here

a MECA_STATIQUE analysis gives exactly the same results as a quick analytic with beam theory

the contrary would be strange

jean pierre aubry

]]>But I stand with my explanation until someone corrects me. I think theres something wrong with the rigidity.

Jonas

]]>Hi everyone,

Thanks again for your help and your time. I've done few more test, especially mass estimation at initila state (that i've done before) but also after deformation: The mass actually increases during computation from 3.79200E-01 ton (379.2 kg) to 3.13166E+01 ton (31 316 kg)!

The more I look at it, the more I think there is a loop between element deformation that increases the volume and the element mass, and weight estimation that increases element length. What do you think, is this something that have been seen somewhere?

Thank you all

That is 100% not the case. You are doing a linear static analysis. You have a matrix of rigidity and vector of external forces. The basic equation of linear elasticity is rigidity * displacement = external forces. The solver solves this equation for the displacements. The matrix of rigidity is calculted for the initial geometry as is the gravity load (based on volume * density, spread on the nodes of the mesh). In non-linear analysis, the matrix of rigidity is recalculated for the deformed geometry after a given number of iterations.

Edit: Think about the belt like a tightrope. In its initial state, a tiny force in the middle between its two ends is enough to make it sag, because the rope has no angle to counter the force in the center. The more the rope sags and the greater the angle gets, the greater the force has to be, to push the center further down. In your analysis the calculation is done with the rigidity of this initial state, where a tiny force is enough to bend your belt to infinity.

Try the following: Make the belt slightly v-shaped, just to test for plausibility. I bet you won't see these large DZ-values anymore

]]>So this is not a problem of code_aster specifically, but rather lies in the nature of the mathematics behind FEM in general. I have to admit that my knowledge of the theory of the finite element method does not go beyond the basics.

I think this could be a case fo a nonlinear-analysis with large displacement. I think the initially calculated matrix of rigidity for the flat belt is just wrong and does not represent the state of the belt hanging through at all (maybe someone with more knowledge about the theory of FEM can explain this a little better).

Jonas

]]>Thanks again for your help and your time. I've done few more test, especially mass estimation at initila state (that i've done before) but also after deformation: The mass actually increases during computation from 3.79200E-01 ton (379.2 kg) to 3.13166E+01 ton (31 316 kg)!

The more I look at it, the more I think there is a loop between element deformation that increases the volume and the element mass, and weight estimation that increases element length. What do you think, is this something that have been seen somewhere?

Thank you all

]]>>> JDC.py : DEBUT RAPPORT

CR d'execution de JDC en MIXTE

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

! <S> Exception utilisateur levee mais pas interceptee. !

! Les bases sont fermees. !

! Type de l'exception : error !

! !

! Solveur MUMPS : !

! La solution du système linéaire est trop imprécise : !

! Erreur calculée : 2.63157e-06 !

! Erreur acceptable : 1e-06 (RESI_RELA) !

! !

! Conseils : !

! On peut augmenter la valeur du mot clé SOLVEUR/RESI_RELA. !

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

fin CR d'execution de JDC en MIXTE

well, it's quite deformed for linear elastic

]]>Hi Miib, here are the values in IS:

young_mod = 205e9 #Pa

grav = 9.810 #m/s²

density = 7900 # kg/m³

# Thickness of the belt in mm

thick = 1.5e-3 #m

Thank you

it is steel

in the next days (i haven't wife/girlfriend ) i will study (gratis) your case.

Stay tuned .

]]>