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by Groguigui
Fri Apr 21, 2017 1:18 pm
Forum: FEM
Topic: Element Membrane M3D6
Replies: 13
Views: 363

Re: Element Membrane M3D6

It is exactly what I did, but this message appear : *ERROR reading *SHELL SECTION: *SHELL SECTION can only be used for shell elements. Elemenrt 11 is not a shell element. But I don't understand totally if I must use *Shell Section or *Solid Section. http://www.dhondt.de/ccx_2.12.pdf p445 : *SHELL SE...
by Groguigui
Fri Apr 21, 2017 8:34 am
Forum: FEM
Topic: Element Membrane M3D6
Replies: 13
Views: 363

Re: ERROR : too many cutbacks

Thanks, that is very interesting! You're right, membrane element must be better in my case. Actually, if I write M3D6 in "*element type", instead of S6, FreeCAD say : *ERROR reading *SHELL SECTION: *SHELL SECTION can only be used for shell elements. Element 11 is not a shell element. Obvio...
by Groguigui
Thu Apr 20, 2017 12:15 pm
Forum: FEM
Topic: ccxInputWriter vs. Faces
Replies: 14
Views: 303

Re: ccxInputWriter vs. Faces

We can also notice that when you remesh (but with same boundary condition) in a similar case (biaxial tensile test) freeCAD bug in ccxInputWriter : face 1 and face 3 have same nodes to apply fix constrain. In the same way, I don't understand why with DLOAD lot of node are constrain with negative for...
by Groguigui
Wed Apr 19, 2017 1:41 pm
Forum: FEM
Topic: Element Membrane M3D6
Replies: 13
Views: 363

Re: ERROR : too many cutbacks

So I would expect non zero normal stresses on your shell elements. And you're right! Plane stress (or plane strain) needs special element types which can be used only on 2D model in xy plane in Calculix. I understand, that is why I have non zero normal stresses, because applied pressure is normal o...
by Groguigui
Wed Apr 19, 2017 11:34 am
Forum: FEM
Topic: Element Membrane M3D6
Replies: 13
Views: 363

Re: ERROR : too many cutbacks

Yes Bernd, I saw, but I think isn't possible to set cutback in FreeCAD. Anyway, actually I have another problem. :lol: Do you know why FreeCAD solve a stress in third dimension when we use a shell element? Usually, it must be zero with plane stress hypothesis. Actually I would like to solve a hypere...
by Groguigui
Fri Apr 07, 2017 9:28 am
Forum: FEM
Topic: Element Membrane M3D6
Replies: 13
Views: 363

Re: ERROR : too many cutbacks

Thanks,

Finally, I found how solve my problem : I used *Controls fonction to set increments and cutbacks. :P
http://web.mit.edu/calculix_v2.7/Calcul ... de179.html
by Groguigui
Thu Apr 06, 2017 11:19 am
Forum: FEM
Topic: Element Membrane M3D6
Replies: 13
Views: 363

Element Membrane M3D6

Hi, I would like to simulate a spherical shell with internal pressure, like a ball, with hyperelastic material (Neo Hooke and Yeoh), to compare with analytical solution. But the model never converges, always for same reason : "*ERROR : too many cutbacks best solution and residuals are in the fr...
by Groguigui
Tue Apr 04, 2017 9:35 am
Forum: FEM
Topic: Cauchy ou Piola-Kirchoff stress?
Replies: 2
Views: 156

Re: Cauchy ou Piola-Kirchoff stress?

Thanks Sodelo, Guido is really the best guy to answer your questions. He is obviously very good in his field. I have already ordered his book. ;) Could you please describe your reference solution and how you want to simulate it with Calculix? What do you mean by "reference solution"? To si...
by Groguigui
Mon Apr 03, 2017 1:22 pm
Forum: FEM
Topic: Cauchy ou Piola-Kirchoff stress?
Replies: 2
Views: 156

Cauchy ou Piola-Kirchoff stress?

Version 0.17 10460 2017/03/08 Ubuntu 16.04.2 LTS 64-bit master 91c59c7910436c44ede608e29d9a90a287121a11 Hi everybody, I would like to develop some hyperelastic incompressible models with calculix in my laboratory, but before this, it is necessary to test calculix. For this, I do some simple cases l...
by Groguigui
Mon Apr 03, 2017 12:39 pm
Forum: Forum français
Topic: Contraintes de Cauchy ou Piola-Kirchoff?
Replies: 1
Views: 95

Contraintes de Cauchy ou Piola-Kirchoff?

Version 0.17 10460 2017/03/08 Ubuntu 16.04.2 LTS 64-bit master 91c59c7910436c44ede608e29d9a90a287121a11 Bonjour à tous, Dans le but de bosser en hyperélasticité (en modifiant l'INP à la main), on teste actuellement Calculix (via FreeCAD) en le comparant à des cas simples. On remarque qu'en 3D, trac...

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