CYCLIC SYMMETRY Error when Slave/Master contain some nodes from fixed surface

1

Good Morning,

I have some trouble with symmetry.
I have 1/4th of a symmetry plate which is attacked by gravity. I created a support at the green surface, a Master Surface and a Slave Surface with nodes.

image
image719×643 119 KB

I want to use symmetry, thus I used the *CYCLIC SYMMETRY Card. Unfortunately, it doesn’t work. I get the following error message.

ERROR in cascade: the DOF corresponding to node 1 in direction 1 is detected on the dependent side of a MPC and a SPC.

If I understand it correctly, it is not allowed to have the same points in my Master/Slave and in my support surface because they have different ways to calculate the boundaries. However, if I remove the support the spooles solver read the input and starts.

Here is some part of my file:

*Surface, Name=Master, Type=Node
Internal-1_Master
*Surface, Name=Slave, Type=Node
Internal-2_Slave

*TIE,CYCLIC SYMMETRY,POSITION TOLERANCE=1.,NAME=T1
Slave, Master
*CYCLIC SYMMETRY MODEL, N=4,NGRAPH=4
0.,0.,0.,0.,0.,-1.

*Step
*Static

*Boundary, op=New
*Boundary
Internal_Selection-1_Disp_rot-1, 1, 1, 0
Internal_Selection-1_Disp_rot-1, 2, 2, 0
Internal_Selection-1_Disp_rot-1, 3, 3, 0

*Dload
Solid_part-1, GRAV, 9810, 0, 0, -1

Is there a way to solve my problem with symmetry? I read something about the *EQUATION card but I haven’t really understood the use of it and how to use it.

Calculix: 2.16
OS: Windows
GUI: PrePoMax v0.9

I wish you all a nice day!

2

There could be trouble, If you use
nodes with *Boundary and the same nodes
with another card like in a set for *TIE master & slave
(except *Cload,…)

3

You can use *BOUNDARY (“a SPC”) on nodes of the master surface but not the slave (“the dependent side of a MPC”). It’s not needed on slave nodes since the slaves automatically follow their corresponding masters’ constraints.

2 Likes
4

Thank you for your answer. And actually it makes sence. I removed all the constrains from the slave and it works now. Thanks a lot!

image
image655×547 162 KB

1 Like
5

Hi

Could you give more information as to how you removed the constraint from the slave?

6

You use the nodes to set the boundary conditions and not the surface. You can do it by selecting all of them by surface.
After that you can deselect single nodes which are on the slave surface. And this is what I have done. It wasn’t very handy but ok for my needs.

1 Like
7

Ah right :slight_smile:

That makes sense now. I appreciate the assisstance. Thanks a lot!