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#1 Code_Aster usage » Question on output the results using "IMPR_RESU" » 2019-03-12 13:55:01

chenghui62000
Replies: 2

Dear all,

There is a question about how to output the results file.
Currently, I used the DYNA_NON_LINE solver to solve the dynamic equation of my study object-- a cage net. The flow chart of my calculated method is shown below. I output the results using "med" format and want to use the "ParaVis" to processing the results to see the dynamic response depended on the time. However, I can not get the time historical results. I guess it is due to the  changing name when calling the DYNA_NON_LINE solver:

resn[k] = DYNA_NON_LINE(CARA_ELEM=elemprop,

Is there any way to get the animation of the dynamic response of the structure using the med format? if not should I change it to other kinds of format, or i need to write a script to do that?
Flow%20chart%20of%20codeaster.png?raw=true

best regards,
Hui Cheng

#3 Code_Aster usage » [SOLVED] How to import my own python module into .comm file » 2019-03-11 10:32:14

chenghui62000
Replies: 2

Dear everyone,

There is a question for the comm file. I have written a lot of python function and class to calculate the hydrodynamic forces of marine structures. Is there any way to use the "import" method to implement my own python module into the .comm file just like following.
(supposed my module located in "/home/hui/codeasterWorkspace/extralmodule/hydro.py")

 import numpy as np

Best regards,
Hui Cheng

#4 Re: Code_Aster usage » [SOLVED] How to apply multiple boundary conditions using a FOR loop? » 2019-02-26 19:53:36

Hi Jean Pierre Aubry,

Is the node name defined by you self manually or generated automatically?
I have a mesh (.med), created by Salome. I find it is not practical to give each node a name(1344 nodes). So I just give them a group name, can I use you method to assign the forces with python loop?

Best regards,
Hui Cheng

#5 Re: Code_Aster usage » [SOLVED] How to apply multiple boundary conditions using a FOR loop? » 2019-02-26 18:43:24

Hi Jean Pierre Aubry,
Thank you for your information.

lc= [None ] * ( iter+ 1 ) ;
lcm= [None ] * ( iter+ 1 ) ;
for i in range ( 1 ,iter+ 1 ) :
    grpno=’cycl%02g’ %i ;
    lc[i]=AFFE_CHAR_MECA( MODELE=model ,
             FORCE_NODALE=_F(GROUP_NO= (grpno , ) , FZ= −100 , ) ,) ;

can you give a little explaination on " grpno=’cycl%02g’ %i ;" ?
My guess: will it give an iterated group names: cycl%02g1,  cycl%02g2,  cycl%02g3?

Best regards,
Hui Cheng

#6 Re: Code_Aster usage » [SOLVED] How to apply multiple boundary conditions using a FOR loop? » 2019-02-26 16:17:27

Hi, I think I also need this automatic boundary-assignment method for my research. ~

#7 Re: Code_Aster usage » How to run ASTK independently? » 2019-02-26 15:41:09

Thank you all for your help. I have to say, that ASTK is quite useful to create the calculation environment. For now, I am usually using ASTK to generate the .export file, and then use "as_run" in the terminal to do the simulation.

#8 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-23 23:33:02

Thank you Konyaro and Jean Pierre Aubry,
It is your kindly help makes me feel confident in this software.

#9 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-21 12:15:55

Hi Jean Pierre Aubry,

Thank you for your reply. Please forgive my knowledge gap, did you mean I need to define an initial speed or acceleration in the .comm file? or I need to define time-dependent load using AFFE_CHAR_MECA_F? Or I need to change the element? I have seen a case in the forum (a cable-coque connection case), there seems no initial definition for speed or acceleration in the .comm file.

BTW, the reason why I want to use the DYAN_NON_LINE: I want to see how the net is deformed in the real-time domain.


Thank you very much,
Hui Cheng

#10 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-21 10:07:09

Hi, Jean Pierre Aubry,

From my point of view, the distinction between the dynamic and the static analysis on the basis of whether the applied load has enough acceleration in comparison to the structure's natural frequency. If a load is applied sufficiently slowly, the inertia forces (Newton's first law of motion) can be ignored and the analysis can be simplified as static analysis.

Dynamic analysis can be used to find dynamic displacements, time history, and modal analysis. A dynamic analysis is also related to the inertia forces developed by a structure when it is excited by means of dynamic loads applied suddenly (e.g., wind blasts, explosion, water current forces).

Best regards,
Hui Cheng

#12 Re: Code_Aster usage » How to run ASTK independently? » 2019-02-20 23:19:33

Hi, Jean Pierre Aubry and GPSalachs
Thank you for your reply, I am trying to install the code_aster independently according to one YouTube tutorials. The reference link is as below:

" http://www dot youtube dot com/watch?v=HQTiy3ixNro&t=1118s"

The question is that: After I source the profile.sh using this command in the terminal:

source /opt/aster/etc/codeaster/profile.sh

I can run ASTK when I type the name in that terminal, but it could not work in a new terminal.
Is there a good solution to run the ASTK in a new terminal without using the above source... code again?
Best regards,
Hui Cheng

#13 Code_Aster usage » [SOLVED]Question on extracting the acceleration during simulation » 2019-02-20 23:02:56

chenghui62000
Replies: 4

Dear all,

Recently, I come with a question when I tried to extract some results using POST_RELEVE_T during the simulation. The extraction code is shown as below:

    tbl[i] = POST_RELEVE_T(ACTION=(_F(OPERATION='EXTRACTION',   
                              INTITULE='Nodal Displacements',
                              RESULTAT=rsn[i],                      # The result from which values will be extracted(STAT_NON_LINE)
                              NOM_CHAM=('DEPL',),              # Field to extract. DEPL = Displacements
                              NOM_CMP=('DX','DY','DZ'),       # Components of DISP to extract
                              GROUP_NO='allnodes',               # Extract only for nodes of group DISP
                              INST=10,                                     # STAT_NON_LINE calculates for 10 INST. I want only last INST
                               ),
                              ),
                              );

The question is that: it can only extract the displacement from the STAT_NON_LINE results. When I change the

 NOM_CHAM=("DEPL") 

to

NOM_CHAM=("ACCE") 

or   

NOM_CHAM=("VITE")

.
It did not work. I gust it is because of the STAT_NON_LINE do not provide the port to access the node's velocity and acceleration.
When I change the solver to DYNA_NON_LINE, the above code can be used to extract the velocity and acceleration.

Best regards,
Hui Cheng

#14 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-20 21:10:26

Hello,  Thank you all for your kindly help.

There is one more question for this case: Can I use the DYNA_NON_LINE solver to do the same simulation?
Assume the same boundary condition, it should get the same result?
I have tried to modify the .comm file, but the outcome seems wrong (at least not same with the STAT_NON_LINE simulation).
Could you please help me to check the .comm file?

Thank you in advance.
Hui Cheng

#15 Re: Code_Aster usage » Testcase fail to run SDNL102a » 2019-02-19 09:12:04

jeanpierreaubry wrote:

i cannot see any picture
please post the .export file

As you said, I upload the .export file.
Thank you for your advice.

#16 Re: Code_Aster usage » Testcase fail to run SDNL102a » 2019-02-18 22:35:07

Dear all,
Thank you for your kindly reply.
Here is how I set this case in ASTK and the results in paravis.
If there is any problem I made in the setting, please share your advice. I am still a newbie in this software.
Best regards,
Hui Cheng
Screenshot%20from%202019-02-18%2022-30-19.png?raw=true
Selection_001.png?raw=true

#17 Code_Aster usage » How to run ASTK independently? » 2019-02-18 14:55:37

chenghui62000
Replies: 6

Dear all,

Recently, I have found that ASTK is a very good module to do the simulation. However, the newest version (V2018.0.1) does not provide ASTK on the toolbar. I have to first start the "Asterstudy", and then Run "Astk" from Tools-Plugins-code_aster. 

How do you think of this? and any advice to open ASTK more efficiently?

Best regards,
Hui Cheng

#18 Re: Code_Aster usage » Testcase fail to run SDNL102a » 2019-02-17 22:01:37

nirmaljoshi wrote:

You are correct. Seems the files are missing.

What a pity. That some of the test cases are not complete.

mecour wrote:

Not every test case is prepared with mesh in med file format. SDNL102a uses the ASTER mesh format. You can find the mesh in file sdnl102a.mail. Also in comm file is this file used in MAVENT=LIRE_MAILLAGE(FORMAT="ASTER",UNITE= 32).

Thank you for your reply. I have checked the data Files, and it did not find any mesh file for UNITE=32. (see the below figure)
p1
p1

#19 Code_Aster usage » Testcase fail to run SDNL102a » 2019-02-16 20:40:42

chenghui62000
Replies: 9

Dear all,

I am trying to run a test case in order to understand how the "wind" force is applied to the cable structure. but it could not run successfully.
I think this may because one of the .med files is missed. So the FCXV function cannot be accomplished.

Do anyone could successfully run this test case on your computer?

#20 Re: Code_Aster usage » How to define a displacement-depended forces in code_aster? » 2019-02-15 20:13:16

What I am trying now:
(1) extract the coordinate of each node ( X, Y, and Z) at each timestep.
(2) calculate the orientation of each (cable) element in the global coordinate system by
          cx= (X1-X2)/L,    cy= (Y1-Y2)/L,    cz= (Z1-Z2)/L.
    L is the (cable) element length. X1, Y1, Z1 is the coordinate of the start of one (cable) element, X2, Y2, Z2 is the coordinate of the end of one (cable) element.
(3) calculate the updated force according to the orientation. The force is written as
        Fx=A*cx, Fy=B*cy, Fz=C*cz. A, B, C are three constant number.
(4) assign the updated force onto the node at each timestep.

The problem is that I could not extract the coordinate of each node at each time step during the calculation. and I am not sure whether I could assign the updated force onto the node during the simulation.
BTW, I am trying to use the DYNA_NON_LINE solver.

#21 Code_Aster usage » How to define a displacement-depended forces in code_aster? » 2019-02-15 16:18:42

chenghui62000
Replies: 1

Hi everyone,

I am a PhD candidate at the University of Stavanger, Norway. Currently, I get stuck with Code_Aster. I have seen the training material and some tutorial videos, but I still cannot figure out a way to define a formulation to update the forces on the structure according to its displacement.

Would you please help me to solve this problem?

Thank you very much in advance.
Hui Cheng

#22 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-13 22:32:42

Konyaro, Thank you so much!

Konyaro wrote:

The force F3 is applied to the GROUP_NO F2.

Sometimes, I could not find this kind of mistake by myself.

#23 Re: Code_Aster usage » meaning of elastic analysis in Non-linear analysis (U4.51.11) » 2019-02-11 16:59:12

nirmaljoshi wrote:

My question is what is the purpose of defining elastic behaviours (comportment) for non-linear analysis?

I have the seam question.
In my point of view, only we added the CIMPORTEMENT in the solver, the solver can adapt the nonlinear calculation. otherwise, it will take the element as a linear element.
But I do not know how it works in the program.

#24 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-11 10:47:10

Dear all,

Thank you for your help!
Sorry, I am a little to get back this topic because of my Ph.D courses.

1.

Jeanpierreaubry wrote:

i have done a few studies like that
it HAS TO BE DONE with CABLE element

Thank you very much for this information. It saves my time to try different elements. I think that the element's names can be different in software. I had done a similar simulation in ANSYS using beam or bar elements.

2.

Jeanpierreaubry wrote:

the material is very strange to me, very soft

I have changed the density of the material in the new .comm file to make it more realistic (see in the attachment). This material is wildly used in the fishing industry. It is a twine rope in Nylon material, and it is very flexible compared to the metal cable.

3.

Jeanpierreaubry wrote:

with BARRE we have an assembly with to continuous tangent on the nodes
and the elements remain straight
and probably is the structure is in a plane and loaded perpendicular to it
it does not converge at the very step

Thank you for explaining why BARRE cannot be used here. But I am still a little confused that: are the motion equations of the discrete elements is different between CABLE and BARRE? From my point of view, it is may because of the nonlinear behaviour we apply in the cable (see the below code) makes it can solve this problem.

                        COMPORTEMENT=_F(DEFORMATION='GROT_GDEP',
                                        GROUP_MA=('twines', ),
                                        RELATION='CABLE'),

 

4.

konyaro wrote:

The gravity is really needed at the very beginning of the simulation,

Thank you very much for your contributions to this topic. Both yours and jean pierre's comm file helps me a lot to understand the simulation process. I think I got the same results as you.
resultsimage

There are some questions I would like to put out here:
5. Is the thermal dilation coefficient is necessary during the material definition? I have deleted this parameter, and the simulation can still give the same results.
6. The initial load (pre-tension, I think) is important for the simulation because it can avoid the singular matrix. But, it won't bring overestimation in the final results?

elemprop = AFFE_CARA_ELEM(CABLE=_F(GROUP_MA=('twines', ),
                                   N_INIT=10.0,
                                   SECTION=3.14159265359e-06),
                          MODELE=model)

7. There only two forces on the nodes are actually applied to the simulation, I could find the reason why. because I think I have applied all the three node forces in my comm file.

Thank you very much again and best regards,
Hui Cheng

#25 Re: Code_Aster usage » [SOLVED]Problem:the matrix is singular or almost singular.... » 2019-02-03 09:10:49

Thank you for your answering. 

dbpatankar wrote:

I see that you have modeled the net with bar element.

Sorry, I did not see the reasons why the bar elements cannot be used here. I will try to use the calbe elements to reconduct this simulation again.


konyaro wrote:

The deformations seem correct with POU_D_T but not with BARRE elements

It seems very interesting in your results, I was also planning to use the POU_D_T elements. Maybe it can give the same results with the cable element.

The reference simulation can be found in the flowing article.  It used a spring element to do simulation the deformation of the flexible system. "Physical modeling for underwater flexible systems dynamic simulation" (sorry I could not put the link in the reply)

By administrator, the link:
https://www.sciencedirect.com/science/a … 1804001532

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