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#1 Re: Code_Aster usage » ERROR: Structural analysis » 2022-06-25 17:25:23


I started reading your book and it cleared up the mistakes I made, however, I still haven't found an answer to your teaching below.

jeanpierreaubry wrote:

there should be only one element between support for BARRE element not over o dozen as on your mesh
this is a basic of finite element, not only code_aster

Maybe I found it, but I didn't really understand what you meant by that phrase. It seems like something so elementary that I feel like an idiot for not understanding it. Can you explain better?

And, when you say this sentence: "In the above lines we have commented the line with FORCE_POUTRE as code_aster cannot yet calculate with more than one distributed load on beam elements! (PAGE 33)", do you refer to the force of gravity also being linear? That's the way I understood it.


#2 Re: Code_Aster usage » ERROR: Structural analysis » 2022-06-20 20:06:32

jeanpierreaubry wrote:

besides what i said earlier your mesh seems to contain a large number of double nodes

i suggest you to deal with first order problems before tackling second order ones

and maybe read the first chapters of my book there are answers to most of your questions

another point what you specify (as written in the .comm file) is really 5000 N/mm2 and using mechanical properties so grossly out of reality is very dangerous in finite element calculation

I understood,

I'll study and comment again on the post. I believe that it actually has several nodes, because I don't know how to deal with the elements of the set and the connections they would have due to the analysis I would like to do, which is precisely to mix elements that suffer axial forces with elements that suffer bending moments.

Do I need to create a connection between these points? For Code_Aster to share these efforts?

#3 Re: Code_Aster usage » ERROR: Structural analysis » 2022-06-19 19:25:24

jeanpierreaubry wrote:


there are quite a few  mistakes (beginners mistake?) in your files

for the error in the message file it is written in it
read the message and apply what it says
however this is related to second mistake

I understand, but as I said, I tried and was not successful. For this reason I asked about the orientation of the mesh...

jeanpierreaubry wrote:

there should be only one element between support for BARRE element not over o dozen as on your mesh
this is a basic of finite element, not only code_aster

Yes, indeed, these are beginners' mistakes. However, I really don't know about this issue. I didn't quite understand what you wanted to tell me, but I can't assign the BARRE condition to multiple 1D elements? (Why?)
Well, then how do I say that my elements suffer only axial forces?

jeanpierreaubry wrote:

besides that
as an engineer what do you think of the behavior of a structure that is 12*1.5 m with a load of 5000 N/mm2 (5000 N/m²) (which is quite huge!)
whose plating is 1 mm thick and the structural members circular section of 2 mm radius?

The values and geometries assigned to the elements are not met, they do not correspond to the real structure. These arbitrary values were only to ''speed up'' the assembly of the model, later I will put the real values in order to compare them with the study that I carried out in a commercial software.

If you don't mind helping me. Thanks.

#4 Code_Aster usage » ERROR: Structural analysis » 2022-06-19 14:29:53

Replies: 5


I am analyzing a structure, and it presented an error as described in the attached message file.

At first it is necessary to explain that the plate elements were added only to be able to add a force (PRES_REP) in area (N/m²). Unfortunately I couldn't find a way around this. I have no interest in analyzing the plates (shell).

Second, the idea is to combine elements that suffer only axial forces with elements that suffer shear forces and bending moments (1D elements).

What is the influence of element orientation in the analysis? I believe the error is related to this, but unfortunately I couldn't get around it.

Another question is, is it necessary to create a connection between the element groups? (...LIAISON_SOLIDE?!)

And finally, is it possible, at the end of the simulation, to export the information in order to obtain a description (.csv) of each bar element? (i. e. Deformation,..)


#5 Re: Code_Aster usage » Application of FORCE and Boundary Condition » 2022-04-26 16:16:03

Hi Jean and Hélio, thanks for the answers...

jeanpierreaubry wrote:


if you introduce 2D elements (plates) you simplify the introduction of vertical load but you introduce some maybe unwanted stiffness
which will be very important in the horizontal plane
regarding wind load  or seismic analysis will produce very different results
which may not be in agreement with the requirement of the construction code

if you use BARRE elements you can only introduce nodal load FORCE_NODALE
you can use beam elements POU_D_E with a very low bending property and then use a linear load FORCE_POUTRE

Maggoo wrote:

Dear colleagues,

First topic: the application of a force equivalent to the distributed surface loads will require a triangular distribution, in my view, even with the introduction of distributed moments. This won't be easy since you will have to identify the coordinates of each member. I may be over-reacting to the problem, but I don't believe in a trade-off with only benefits.

As Hélio commented, adding the loads distributed on each bar will not be simple. The idea is not to use 2D elements but to keep the 1D analysis... however, apparently, I can't assign the forces related to the areas (N/mm²) to the 1D elements. Of course, I already imagine that, but I was hoping there was some resource that would help me get around it.
Perhaps, distributing this load at the nodal points of the structure can be done... but the results need to be validated.

As for the evaluation of the structure... in fact, the elements that suffer only axial forces I will model them as BARR. The others, within a group, will use POU_D_E.

Maggoo wrote:

I asked, not a long ago, if anyone knew a tool to make standard applications to post-process the results in CA, like the ones available in SAP2000 or Metallica3D, but got no positive answers. I guess you will have to collect the data and do it in an external script. To ease the pain, give mnemonic names to the groups to remember wich section you are dealing with, because the volume of data will be big.

I hope you find a better solution than mine.

Hélio, the idea is precisely to bypass the SAP2000. Let's see how far my study progresses. If you have done something related and don't mind sharing the case with me, I will be very grateful.

Thanks all.

#6 Re: Code_Aster usage » Application of FORCE and Boundary Condition » 2022-04-24 13:14:09

Hi Helio, thanks for the reply.

Like you, I'm also Brazilian.

Maggoo wrote:

Greetings Marcelo,

Would it be possible to make surfaces linking the bars and to apply the loads directly to them through FORCE_FACE or PRESS_REP?

Creating groups with the sides of the faces you would be able to apply BARRE elements to them, even fixing a displaced CG if you need so.

Assigning the BARRE model in AFFE_MODELE tou will be able to apply the BARRE characteristics in AFFE_CARA_ELEMENTS. Read the applicable documents for details.


For sure. The only difference is that I would go from having a 1D model to having a 2D model. It is a very simple structure, there would be no computational difference. The idea was actually to find out if there's a way to do it even in a 1D element model. I will keep searching.

And as you mentioned, I would be able to assign the properties of the beams to the surface contours.
(I would have a mixed model in that case).

But, I think the biggest problem I'm facing is the boundary conditions for each bar in my structure. In SAP 2000 you can say that such element is or is not influenced by bending moments (truss frame elements - a structural element that is designed to support only axial forces - and gantry frame elements). This detail is crucial to my study... Do you know how this is done?

EDIT1: U3.11.01: "Modeling BAR treat only the efforts and axial deformations."
Could this be the way?

#7 Code_Aster usage » Application of FORCE and Boundary Condition » 2022-04-22 20:37:51

Replies: 7


There are three questions I would like help with.

I have attached an image of the structure I need to study. Well, it's basically a platform for people to pass through.

FIRST: As can be seen, the structure is composed of bar elements, something really simple. Based on local regulations (NBR 8800:2008), I need to assign certain loading forces to this structure. These forces are given per unit area (i.e. kgf/mm²).
I believe I can't use FORCE_FACE. In that case, how would I do it? Would I have to calculate by hand what force is distributed on each bar element and apply it (so using FORCE_CONTOUR or FORCE_ARETE)?
I believe there is an easier way, otherwise such an exercise would be quite laborious, even for such a simple structure (calculate the area, divide the loads...).

SECOND: There are elements in this structure that are considered truss frame elements (which do not transmit bending moment) and gantry frame elements. I watched a very interesting video (Search for "Elementos Discretos en Code_Aster - Torre de Alta Tensión" on Youtube), however I still have this doubt, because the properties of how each element behaves were not assigned in the video. How can this be done?

THIRD: This one isn't very important, but for drawing bar elements and their respective nodes, what software makes this activity simpler compared to Salome's Geometry?


#8 Re: Code_Aster usage » Distributed load - POU_D_E element » 2021-03-01 19:36:52

Hi tpa,


The big question now is that the results are not consistent. It is a simple case where I did the analytical calculation and found a 39 mm displacement. For some reason I can't reproduce the case in Code_Aster and I don't know exactly where the errors are. I attached the case and the mesh. The dimensions are in millimeters (L 6500, D 219.08 and EP is 12.7) and the applied force in the length of 3000 mm in the center of the tube is 7 tol. If you can help, or anyone who reads this post.

The DOF that I used analytically (and in this case it was a 2D analysis) was to use one end as Fixed and the other with Roll. One of the issues is that in the real case the weight is supported on a support by the extremities, being able to move on the L axis.

Another very important issue is the fact that I want to do the linear analysis first, although I believe that this type of analysis, due to displacement, is a non-linear analysis, right?

#9 Re: Code_Aster usage » Distributed load - POU_D_E element » 2021-02-27 21:03:33

tpa wrote:

Goto the documentation document u3.11.01 p.5 and realise that you may be right:


#11 Code_Aster usage » Distributed load - POU_D_E element » 2021-02-19 20:37:34

Replies: 5


I am analyzing a simple situation and it is giving an error according to the file below. I believe that the error is in FORCE_ARETE, because it is used for DKT elements. However, I don't know how to add a distributed load over an 1D element and I wanted help.


#12 Re: Code_Aster usage » Topological Optimization » 2020-09-25 17:18:29

I'm also interested in whether there has been progress...

#14 Code_Aster usage » [SOLVED] Augmentez le temps CPU » 2019-12-03 19:16:13

Replies: 5


I'm trying to perform an impact analysis, but... it shows the following error after a while:

   ! <S> Exception user raised but not interceptee.                           !
   ! The bases are fermees.                                                   !
   ! Type of the exception: ArretCPUError                                     !
   !                                                                          !
   !    Arr?t par manque de temps CPU au num?ro d'instant < 46 >              !
   !       - Temps moyen par pas de temps        : 16.410639                  !
   !       - Temps restant                       : 15.457097                  !
   !    La base globale est sauvegard?e. Elle contient les pas archiv?s avant !
   ! l'arr?t.                                                                 !
   !                                                                          !
   !    Conseil :                                                             !
   !       - Augmentez le temps CPU.                                          !

I have attached the .mess file.

I will be very grateful for anyone who can help me.

#15 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-30 14:09:14

konyaro wrote:

Be careful, the FORCE_FACE is a pressure so you must divide the desired force by the area of the surface.

True, I had forgotten that.

I made the modifications and the values are now close, not ''equal''... but I didn't do the mesh convergence test.

Thank you very much for your attention.

#16 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-29 13:54:16


See the result of the analysis in both software. Of course there is no better... far from it, but the results presented by Code_Aster, to my understanding, are inferior and maybe, I'm not sure, could be the responsibility of the boundary condition, what do you think?

EDIT1: I also attached the .mess file.

#17 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-28 13:55:52

konyaro wrote:

be careful with your boundary conditions, you must fix DRX and DRY, not DRZ.

Hi Konyaro,

I did what you recommended and it worked. Thank you very much.

#18 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-25 18:53:57


I tried to reproduce what I had done in the bar, and it had worked, in the shaft.
Unfortunately, a series of errors appeared... which I understood to be from the mesh, but which I honestly don't think was badly done.

Because the mesh file is large, I put it in Google Drive: https:// drive.google.com/open?id=1acwcKCu2r4Ydmug13LB8A4NtzHJ6hYwP (Fixed region = Bearing)

The .mess and .comm files are then attached.
Who can help, I would be very grateful.

#19 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-25 14:26:24

konyaro wrote:

I just changed the names of the groups

Yes, it coincided that we put the message in the thread at the same time, I added an EDIT in the previous message.

EDIT1: I was able to imitate your steps in my case. The results are somewhat distant from those presented in SimScale (where the idea of reproducing them came from), especially when the deformation is analyzed (SimScale max_D: 0.000096m; Aster_Study max_D: 0.001665). However, positive since I managed to run the case.

Do you believe that by following these steps I will be able to solve my shaft case?

EDIT1: Using LIAISON_RBE3 also get similar results to those presented by LIAISON_SOLID.

#20 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-25 13:21:19

konyaro wrote:

p.s. Why don't you insert your attachments directly in your posts? I guess more people would help you. Most of the time I can't open your files, especially your "encurtador" ones.

Hi Konyaro,

I can't attach to the forum because the vast majority of times I've tried 'very large file size' errors.

About the modifications you made, fortunately I was able to access the .comm file, but unfortunately the .med file could not be accessed, it presented error when I tried to import it.
So I can understand the changes that were made to the case, but I can't see the changes made to the mesh.
EDIT1: I was able to imitate your steps in my case. The results are somewhat distant from those presented in SimScale (where the idea of reproducing them came from), especially when the deformation is analyzed (SimScale max_D: 0.000096m; Aster_Study max_D: 0.001665). However, positive since I managed to run the case.

Did you even analyze my shaft case?

#21 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-20 20:01:25

RichardS wrote:

For example this project could be helpful: https://www. simscale.com/projects/rszoeke/pinned_bar_example/

Thank you Richards for the answer.

I tried to reproduce the example case in Aster_Study but unfortunately I am trying similar errors to the ones I had previously. In this particular case he has been giving errors related to orphan nodes. I have tried every strategy I know and none have actually been effective. In SimScale there is a function that creates this node (CALC_MESH_UTILS), but this function does not exist in AsterStudy, so I tried to use the same strategy I was using for my problem, using Salome's own mesh solver.
Honestly, I don't know what to do anymore, I've been studying and haven't been able to find the solution to my problem.

I have attached my study (link: https: //drive.google.com/open?id=1xo-Pb8ZUOtNAQtHJcuBEpR25E253TaQL .mess; .comm and .med files) in case anyone wants to analyze and contribute.

#23 Re: Salome-Meca usage » Error generating mesh » 2019-11-05 19:21:26

dezsit wrote:

...but only quadratic for mechanics, and again do verification and mesh convergence study.

Interesting to mention this, as Salome allows the use of quadratic, bi-quadratic and linear mesh. However, I haven't studied it yet to know the difference in their use and what it really means.

dezsit wrote:

Code_aster fatigue case: as I mentioned the fea part of fatigue is "simple" mechanics (statics, dynamics), not aster specific. We do the fatigue evaluation separately, independently from the fea package, so I cant provide an aster specific fatigue evaluation (knowing that aster has in-built fatigue evaluation tool, but we have not used it yet).

Yes, you had commented and I kept your words. What happened was my failure to believe that perhaps for some reason you had already done a similar analysis using Aster_Study.

Thank you for your teachings.

#24 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-05 18:46:24

dezsit wrote:

3D solid does not have rotational DOF (it is not aster specific, 3D solid does not have rotational dof in any common mechanical fea package!) so you should remove the '-DRY-DRZ' from yout DDL_ESCL definition.

Yes, I know.
I'm just trying to reproduce what I did in commercial software, and the problem, I believe, is precisely trying to reproduce the condition of Remote Displacement (I'll leave this image out of curiosity: encurtador.com.br/lmC23 - pay attention to 6 DOF). Or is it the condition of symmetry?

dezsit wrote:

...and use a DIS_T or DIS_TR modelisation, depending on your needs, and attach a zero stiffness spring to this 0D element (AFFE_CARA_ELEM -> K_T_D_N or K_TR_D_N or whatever, again depending on the problem you modeling).

Yes, on the node I created I added the condition of DIS_TR (6 DOF), but apparently something is wrong. And I made that node not 'orphaned' but in the center of the face.



                                   NOM_GROUP_MA=('Node', )),

                          _F(GROUP_MA=('Node', ),
                             MODELISATION=('DIS_TR', ),


fieldmat = AFFE_MATERIAU(AFFE=_F(MATER=(mater, ),

                                    GROUP_MA=('Force', )),

                   PESANTEUR=_F(DIRECTION=(0.0, 0.0, -1.0),
                                GROUP_MA=('Eixo', )))

                                      GROUP_MA=('Symmetry', )),

                                        DDL_ESCL=('DX-DY-DZ-DRY-DRZ', ),
                                        DDL_MAIT=('DX', 'DY', 'DZ', 'DRY', 'DRZ'),
                                        GROUP_NO_ESCL=('Remote', ),
                                        GROUP_NO_MAIT=('Node', )),

reslin = MECA_STATIQUE(CHAM_MATER=fieldmat,

reslin = CALC_CHAMP(reuse=reslin,
                    CONTRAINTE=('SIGM_NOEU', 'SIGM_ELNO'),
                    CRITERES=('SIEQ_NOEU', 'SIEQ_ELNO'),
                    FORCE=('REAC_NODA', ),



#25 Re: Code_Aster usage » [SOLVED] Stress analysis on a symmetrical shaft » 2019-11-04 18:15:25

jeanpierreaubry wrote:

without the message file it is impossible to tell what is happening

.mess, .comm and .med: encurtador.com.br/gsvJU (Google Drive link)

EDI1: The Fixed condition is not necessary (I unintentionally added it to MECA_STATIQUE, as I had created it only to be able to use it for testing), but... removing it, the same error happens.