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#1 Re: Code_Aster usage » Strange behaviour of K_TR_D_N » 2019-07-17 15:00:32

I understand that, but if I want to fix one end to the ground, I can do it both with K_TR_D_N and K_TR_D_L, Why I must choose the second one?

#2 Re: Code_Aster usage » Strange behaviour of K_TR_D_N » 2019-07-17 07:09:27

I will follow your advice.
Just one question, why it is better to prefer K_TR_D_L? the other one could be unstable?

#3 Re: Code_Aster usage » Strange behaviour of K_TR_D_N » 2019-07-16 14:45:49

I didn't know that. I assume that the discrete element remain "in the air" untill I fix it to the ground.
Then the nodal dof are redundant, and if one node must be free because attached to a component that transmit force, the stiffness must be set to zero.

Thank you

#4 Code_Aster usage » Strange behaviour of K_TR_D_N » 2019-07-16 09:10:47

pironman
Replies: 8

3 weeks ago I posted a topic about the usage of this element. I doing some simulation, but I'm not convinced of the correctness of that usage, thus I made a test simulation (files attached).
I want to relax the rotational degree of freedom of the end of a beam, by using that element connected to the face of the beam with LIAISON_SOLIDE.

1st analysis: The element have 10.0E9 stiffness on all 6 degree of freedom, and I locked all 6 d.o.f. with DDL_IMPO.

01.png

As expected, the beam is full-locked.


2nd analysis: Removed the DRY d.o.f. in DDL_IMPO.

02.png

No differences compared to before, but should be rotate!


3rd Analysis: Added again DRY = 0 in DDL_IMPO, but stiffness along that d.o.f., in AFFE_CARA_ELEM, now is set to 0.0

03.png

Again, no differences compared to the first analysis, but in my opinion should rotate.


4th Analysis:  Removed the DRY d.o.f. in DDL_IMPO and stiffness set to 0.0

04.png

Finally, now it works as expected.
But in my opinion the 2nd, 3rd and 4th analysis must give the same results. Why this behaviour? If I want to set a finite stiffness, for example if I have a suspension from the component to the ground, could be a problem.

#5 Re: Code_Aster usage » usage of discret K_TR_D_N » 2019-07-12 14:42:31

thank you for your reply.
Another question: If I want a certain stiffness? I must use a K_TR_D_L?
what's the utility of K_TR_D_N?

Thanks

#6 Re: Code_Aster usage » [SOLVED] Stress components on a beam » 2019-07-04 14:58:37

I add a question. After that, how can I visualize these stresses? I use Salome-Meca, and visualize the results with ParaView, in that beams I see the displacement, but not the stresses.

#7 Code_Aster usage » Simulate the transmission loss of a muffler » 2019-07-02 10:35:20

pironman
Replies: 1

I want to use the acoustic capability of code aster to obtain the transmission loss of an automotive muffler.
For the mechanical analysis, there are a lot of tutorial and example, but I found nothing for acustic.
Then, I don't know how to start. Anyone can help me?

Thank you

#8 Code_Aster usage » usage of discret K_TR_D_N » 2019-06-27 10:32:12

pironman
Replies: 2

I have to link a 3D component and I want to lock all the degree of freedom, except of rotation in OZ axis.
To do that, I create a 0D element, assign discrete element K_TR_D_N with very big stiffness on kx, ky, kz, kox, koy and zero stiffness around OZ axis.
Then, I use LIAISON_SOLID between this discret element and a surface of interest of the 3D element, and I fix the discrete element with DDL_IMPO = ENCASTRE.
With this method didn't work, but work if I set DDL_IMPO = 0 on DX, DY, DZ, DRX, DRY and nothing in DRZ.
My question is, why? If I set a zero stiffness around OZ axis, the rotation must be allowed also if I fix this degree of freedom with DDL_IMPO, why not?

Thanks

#9 Salome-Meca installation » Access violation problem » 2019-06-25 07:44:03

pironman
Replies: 0

Good morning.
Yesterday, I use without problem Salome-meca for windows, installed in a Windows 10 machine.
I save the results, then today I open the same result of yesterday, try to look at it in ParaView, and gave me that problem:

AccViol.jpg

I repeat the simulation, but I have the same problem.
Yesterday, I visualize without problem that results, why today not?

Thanks

#11 Salome-Meca usage » Dynamic harmonic simulation with hysteretic damping » 2019-05-03 09:12:06

pironman
Replies: 1

I have done a dynamic harmonic simulation of a system without damping. Now, I want to do the same simulation, by adding the damping.
To do this, in the material properties I have add an Hysteretic damping of 0.08 (steel), I modify the ASSEMBLAGE by adding the 3rd matrice RIGI_MECA_HYST, that I call "Ks". Then, in DYNA_VIBRA, I set "MATR_RIGI = Ks".
When I start the simulation, I read this:


Matrices dynamiques pour la résolution
--------------------------------------------------------------------------------------
    >> matrice de masse        : M
    >> matrice de rigidité     : Ks
    >> système conservatif, sans amortissement.


I have a doubt, it is correct my procedure?

Thank you

#12 Salome-Meca usage » Time set after running simulation » 2019-04-30 15:37:38

pironman
Replies: 2

When I run a simulation, appear a window where I can set the value of RAM and the time.
I see that the time is limited to 23:59:59, and that's a problem! I need to simulate a very complex dynamic structure, and the entire simulation take more than 24 hour.
How can I impose a bigger time?

Thanks

#13 Introduce yourself / Présentez vous » Hello from italy » 2019-03-08 10:06:24

pironman
Replies: 0

My name is Mattia, Im 28 and I'm mechanical engineer.
I start to use code_aster at home, because I'm a strong supporter of open source software, and I'm introducing that software also at work place (but I'm the only user right now).

#14 Re: Salome-Meca usage » meshing compound: another way? » 2019-03-08 10:00:42

@jeanpierreaubry, @ppeetteerr
create an individual mesh of each component and then combine it in aster, is a beautiful solution. I'll try in this manner

last point
please introduce your self in the ad hoc section of the forum

you're right. Now I'll do it

#15 Re: Salome-Meca usage » meshing compound: another way? » 2019-02-27 13:54:20

thank you for the tutorial.
I try to do it, but didn't work, maybe because I import step geometry, and don't create geometry directly on geom module.
But it's good food for tought, i'll try again

#16 Salome-Meca usage » meshing compound: another way? » 2019-02-19 15:39:13

pironman
Replies: 6

I made some simulation of large file, made by shells, solids and nodes where I put discrete elements.
My procedure was:

1) Import STEP file
2) Explode it into shells and solids
3) Create vertices where I want the 0D elements
4) Make a partition with all the exploded elements and the vertices
5) Explode again the partition into vertices, solids and shells.
6) Create groups where I want to put LIAISON_SOLIDE, link, forces and so on
7) In the mesh module, I create a "empty" mesh of the partition
8) Then, I create one sub-mesh for each component
9) I compute the main mesh, add the group and so on

After that, I set the simulation in the aster module. All works, no problem.

Now, the problem: After the simulation, I want to modify one component of the geometry. It's ridiculous, because I must repeat the entire procedure, recreate groups and so on. It's more or less 2 hour of work every time.
I've done that 2-3-4 times, but... there is another faster way to do that?

Thank you

#17 Re: Code_Aster usage » Exclude elements from analysis » 2019-02-15 16:26:23

It works, thank you!
I remove the elements and the materials.

#18 Code_Aster usage » Exclude elements from analysis » 2019-02-02 09:51:55

pironman
Replies: 2

Good morning.
I made a simulation of a complicated compound (lots of component, both shell, 0d and 3d), and now I want to remove some of these components from the simulation, without repeat all the work in the geometry module, mesh again and so on.
There is a possibility to do that?
If not, will it work if I put in these parts a material with zero density and stiffness?

Thanks

#19 Re: Code_Aster usage » DKT vs DKTG » 2019-02-02 09:44:58

Ok I understand, Thank you

#20 Code_Aster usage » DKT vs DKTG » 2019-01-31 14:34:19

pironman
Replies: 2

I searched a lot, also in the documentation, but I don't understand the differences between these two elements.
Anyone can help me please?

Thank you

#21 Salome-Meca usage » Remove element from paraview » 2019-01-30 16:35:15

pironman
Replies: 0

Hello, I simulated a component made by more shell elements, to create a box.
Now I want to remove some element of that box, but only from the visualization, to save some picture of the inside of that box.
Is it possible?

Thanks

#22 Re: Code_Aster usage » Simulate a mesh composed by more solids » 2019-01-28 10:05:28

Now I'm trying with LIAISON_MAIL, and I obtain this error message:

   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   ! <S> Exception utilisateur levee mais pas interceptee.                       !
   ! Les bases sont fermees.                                                     !
   ! Type de l'exception : error                                                 !
   !                                                                             !
   !  les 12 mailles imprimées ci-dessus n'appartiennent pas au modèle           !
   !  et pourtant elles ont été affectées dans le mot-clé facteur : LIAISON_MAIL !
   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

#23 Re: Code_Aster usage » Simulate a mesh composed by more solids » 2019-01-25 10:06:24

Thank you, but I want to connect two solid not in contact between them, then I can't use partition.

#24 Re: Code_Aster usage » Simulate a mesh composed by more solids » 2019-01-22 10:49:21

Right now, I solved by adding some 3D-parts that connect the two sub-meshes, and works. In this case is ok, but in some case I need to connect two submeshes, and I still don't know how to do that.

Any help?

Thank you

#25 Re: Code_Aster usage » Simulate a mesh composed by more solids » 2019-01-17 15:08:56

Hi, here there is an archive with the .hdf file.

https://drive dot google dot com/file/d/1dpCnry2a76gR4aeaI8FzkGr8xNqDUzGM/view?usp=sharing

Thank you

P.S. Another one, in which I have modified the group of nodes, but the results are the same (doesn't work)

https://drive dot google dot com/file/d/1G2LxzGznt7_RbhGSYgz96Rtvy3W-k1ve/view?usp=sharing