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#1 Re: Salome-Meca installation » Questions about singularity version of salome_meca 2021 » 2021-10-04 21:58:05

The container version of SM2021 (Singularity) is much more robust and is also easy to install.

#2 Re: Code_Aster usage » Mesh formulation for hyperelastic case » 2021-09-24 09:05:55


Question récurrente des copains de Lille qui font de la bio-mécanique

Les matériaux hyper-élastiques ont souvent un comportement incompressible.

En toute rigueur, on devrait donc utiliser une formulation adaptée pour éviter les problèmes de verrouillage numérique: sous-intégration (3D_SI), formulations mixtes (UP, UPO, UPG) voire HHO

Mais ELAS_HYPER dans aster n'est pas branché sur les formulations mixtes type UP, UPO, UPG, non pas à cause de l’incompressibilité mais parce qu'il s'agit de grandes déformations de type "GROT_GDEP" qui ne sont pas le modèle de référence (GDEF_LOG ou SIMO_MIEHE).

Mais comme le terme volumique est pénalisé dans sa formulation, en général, ça fonctionne quand même assez bien en 3D primal. Si ça commence à verrouiller, le 3D_SI est une bonne option

Ce défaut va probablement disparaître dans quelques temps d'ailleurs.

#3 Re: Code_Aster usage » [SOLVED] Error on complex curved sheet metal with shell elements » 2021-08-25 15:33:34


The local reference frame of a plate element is defined by normaland (two) tangents.

The normal is defined by MODI_MAILLAGE/ORIE_COQUE.
The first tangent is, by default, the global X axis.

So, if the plate/shell element is orthogonal to X axis, tangent and normal are colinear. Not possible !

"It is necessary to modify the reference axis (axis X by defect) by using  ANGL_REP or VECTOR"


NB: SIEQ_ELNO is not necessary in CALC_CHAMP, it's automatic since at least 15 years.

#4 Re: Code_Aster usage » What is the real meaning of KINC and KSTEP in code aster? » 2021-08-06 10:35:52


KINC/KSTEP are ABAQUS words, not code_aster !

Nevertheless, in code_aster, KSTEP is the time step (by parameter INST in code_aster). It's real time for dynamic and only parameter for quasi-static analysis.
It's defined by DEFI_LIST_REEL + DEFi_LIST_INST and INCREMENT in STAT_NON_LINE for instance
KINC is the Newton iterations. KINC=0 is the prediction for instance.
In code_aster, you can control number of Newton's iteration, see NEWTON and CONVERGENCE keywords in code_aster as ITER_GLOB_MAXI is the maximum number of Newton's iteration for each time step

#5 Re: Code_Aster usage » Could someone share the theory document R5.01.05 ? » 2021-08-06 10:30:45


I haven't taken the time to write the theoretical documentation yet. Sorry !
Nevertheless, among the proposed methods, there is the APHR method of D. Ryckelynck, developed in code_aster with him! You can look in the thesis of Tuan Dinh Trong (https://  www.theses.fr/2018PSLEM023.pdf)
The DEIM method is applied in three stages:
1 / Consruction of the mesh groups starting from the dual base (stresses) using DEFI_DOMAINE_REDUIT and magic points
2 / Construction of a new MODEL on this mesh group, and therefore need to change the AFFE_CHAR_MECA for example
3 / Use of the method in STAT_NON_LINE or THER_NON_LINE
The procedure is used in the tests zzzz395

#6 Re: Code_Aster usage » [SOLVED]Error in Compile a UMAT » 2021-06-30 21:14:30


Hmmm, I don't know. Maybe rename you file VPSCmodule_module.F90

#8 Re: Code_Aster usage » [SOLVED] No Result File Created when Simulating Two Volumes in Contact » 2021-05-17 21:08:09


You computation has failed, see "Abnorml abort " during MECA_STATIQUE

#9 Re: Code_Aster usage » Bogue avec POU_D_T et chargements PRE_EPSI » 2021-05-17 12:12:09


Pourquoi l'effort serait nul ?
On applique un effort élastique proportionnel  à une déformation donnée.
D’après les données de votre calcul, je trouve N = E*A*Exx =  69104502.6682824 (votre unité)
Je pense plutôt que ce n'est pas exactement le chargement ce que vous cherchiez
Si vous voulez appliquer une déformation thermique, ce n'est pas la bonne méthode par contre. Regardez le test sdll154a plutôt

#10 Re: Code_Aster usage » [SOLVED] CALC_CHAMP cannot read from 2nd list of EVOL_NOLI » 2021-05-10 21:12:55

You need loads to compute REAC_NODA.
But in your version, we ask for loads BEFORE knowing if you're computing REAC_NODA ! It's useless

#12 Re: Code_Aster usage » [SOLVED] CALC_CHAMP cannot read from 2nd list of EVOL_NOLI » 2021-05-06 21:07:56


This is a bug that seems to me to have been corrected recently.
An idea: to avoid destroying the loads before CALC_CHAMP.

#13 Re: Code_Aster usage » Reference for DKT elements » 2021-05-06 21:02:48


The original work :
J.L. Batoz, K.J. Bathe, L.W. Ho, A study of three-node triangular plate bending elements.
International Journal for Numerical Methods in Engineering, 15: 1771-1812, 1980.

For quad4:
J.L. Batoz, M. Ben Tahar, Evaluation of a new thin plate quadrilateral element. International
Journal for Numerical Methods in Engineering, 18: 1655-1678, 1982

It is very strange that these references are not in the documentation !

#14 Re: Code_Aster development » Solid shell elements in Code Aster » 2021-04-26 21:15:12


The old version of SHB required special behaviors with the assumption of the plane constraints

This is not the case for the new version of the solid shell elements available in version 15.3
These elements are also usable in large deformations (DEFORMATION = 'GDEF_LOG')

To use them from HEXA8 only:
1 / Modify the mailalge by CREA_MAILLAGE / COQUE_SOLIDE

A version with PENTA6 will soon be available

#15 Re: Salome-Meca usage » errors in analysis » 2021-03-21 00:06:00


Using DKT elements, plate elements. Using surfacic mesh (QUAD and TRI, linear), not volumic !

#16 Re: Code_Aster usage » Error while using FLUI_STRU » 2021-03-02 22:50:09

You have a workaround: use a vect_asse instead a load in DYNA_VIBRA

Phase 1: construct a vect_sse from load
pres = AFFE_CHAR_MECA(PRES_REP = _F(PRES= 5, GROUP_MA='Structural'))
   numeDDL = NUME_DDL(MODELE=model)
  => NB: as you use a rigidity matrix/mass matrix, you have this object when assemblying matrices

veAsse = ASSE_VECTEUR(vect_elem=veElem, NUME_DDL=numeDDL)

  => NB: if you're sing ASSEMBLAGE? you can add your load

                          VECT_ASSE= (_F(VECTEUR=veAsse, OPTION='CHAR_MECA' , CHARGE= pres))

Phase 2: use vect_asse instead of load in DYNA_VIBRA
DYNA_VIBRA (EXCIT=_F(VECT_ASSE=veAsse)) instead of CHARGE=pres

I'm not sure of the exact syntax but idea is here !

#17 Re: Code_Aster usage » Error while using FLUI_STRU » 2021-03-02 22:41:36


Ho, I see:

"If you use a command of “computation” (THER_LINEAIRE, STAT_NON_LINE, ...), there is not way to work around this problem. It is necessary to change modeling or to emit a request for evolution."

It's possible since 15.1.7

#18 Re: Code_Aster usage » Error while using FLUI_STRU » 2021-03-02 07:34:39


In your version, you cannot apply pressure on FSI elements

Apply on the structural elements

#19 Re: Code_Aster usage » Poutres courbes (POU_C_T) plus supportées ? » 2021-02-25 22:24:22


Ces éléments sont été supprimés pour simplifier le code et avoir accès aux mêmes options que les POU_D_T sans développement supplémentaire, on peut aiss passer directement aux tuyaux sans remaillage et avoir de meilleurs visualisations.
Il suffit de mailler avec quelques éléments de poutre droite pour avoir la même précision
On peut toujours introduire les coefficients de flexibilité et les corrections de contrainte si nécessaire

#20 Re: Code_Aster usage » <A> <FONCT0_9>! Erreur lors de l'interpolation de la fonction 'dx1'. » 2021-02-19 09:20:36

demerss wrote:


I think the AFFE_CHAR_MECA_F works only with functions that arguments are ('INST', 'X', 'Y', 'Z') [U4.44.01]

Correct !

#21 Re: Code_Aster usage » [SOLVED] PILO_PRED_ELAS + E modulus field = <EXCEPTION> <CALCUL_31> » 2021-02-19 07:35:08


No solution  !
You cannot use external state variable (AFFE_VARC) with ENDO_FISS_EXP (or ENDO_SCALAIRE) and PILOTAGE='PRED_ELAS'


#22 Re: Code_Aster usage » Utilisation maillage format .datg » 2021-02-17 14:58:54


Si vous importez le cas-test sous Asterstudy, il va trouver le bon maillage
Si vous le faites "à la main", il faut regarde le fichier ssnl126b.export:

F comm ssnl126b.comm D 1
F datg ssnl126b.datg D 16
F mmed ssnl126a.mmed D 20

On voit que ce test utilise le même maillage que le ssnl126a.

#25 Re: Code_Aster usage » [SOLVED] Restart of Contact Analysis with friction (POURSUITE) » 2021-02-10 18:24:28


You are right, it is often difficult to restart computation with contact and friction. In V14 / V15, it is normally more robust. there are two reasons:
- the phase of pairing not being really saved, if the problem is a little difficult (non-convexity of the contact surfaces), one can have slight variations between a monobloc calculation and a calculation in several stages
- for friction, nothing can be done against a more fundamental problem: friction loses important mathematical properties, in particular the uniqueness of the solution when the Coulomb coefficient "is not small", which gives results different. None is wrong, there are several!