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## #1 2016-12-11 07:20:37

konyaro
Member
From: Genève
Registered: 2016-04-02
Posts: 255

### [SOLVED] Convergence with POU_D_T_GD

Hello,
I’m facing difficulties with the POU_D_T_GD element with large rotations.

1) A simulation with only one beam: one node is rotated on 360°. I can achieve convergence but the convergence depends on the radius of the beam. R=1 perfect, R=10 difficult, R=50 perfect… anyway it converges. (but not possible to rotate more than 360°).

2) A simulation with 2D C_PLAN elements linked to a single node with beams. The single node is rotated on 360°.
R=0.01-1: nice convergence
R=1.0: converges, strange deformation of elements on the last steps
R= 5, 10 or 15: no convergence
R= 20: converges, strange deformation of elements

3) A simulation with 3D elements linked to a single node with beams. I cannot achieve convergence. The best radius is around 1.0 which allows to rotate about 198°.

I cannot understand:
- Why is the convergence related to the radius of the beams even though there are no forces ?
- Why is it so hard to achieve convergence ?

Any idea would be welcomed!

Konyaro

Attached:
- comm, med and mess files
- gif animations of the 3 cases

Last edited by konyaro (2018-10-07 19:02:40)

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## #2 2017-02-25 15:36:07

konyaro
Member
From: Genève
Registered: 2016-04-02
Posts: 255

### Re: [SOLVED] Convergence with POU_D_T_GD

Another example with a rotating part. With 3D or C_PLAN elements convergence is fast and robust. As soon as a POU_D_T_GD is inserted somewhere strange distortions appear and convergence is hard to achieve. cf animation below.

Last edited by konyaro (2018-10-07 18:56:37)

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## #3 2018-10-07 19:02:04

konyaro
Member
From: Genève
Registered: 2016-04-02
Posts: 255

### Re: [SOLVED] Convergence with POU_D_T_GD

I close the topic as the problem is explained in the following topic:

https://code-aster.org/forum2/viewtopic.php?id=23652

I'm looking forward to the new 2019 elements :-)

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