Periodic boundary conditions in ABAQUS

**roaneb** · 2006-07-30, 19:29

Hello All;

Does anybody know how to apply periodic boundary conditions in ABAQUS?

Thanks.

**roaneb** · 2006-07-31, 10:59

I was able to find the equation constraint feature in which one can write equations between given sets of nodes for particular dofs. Using this, one should be able to create periodic bc's.

Answered my own question, but I still hope this is helpful.

**Jorgen** · 2006-07-31, 15:34

I agree, the *Equation command can be used to create periodic boundary conditions.
I have used it many times in the past, here's an example showing the compression of a foam cell:

- Jorgen

**roaneb** · 2006-07-31, 22:26

Do you have any suggestions for applying "body forces" in the case of incompressible materials with all periodic BC's? Of course, this is using ABAQUS as well.

Thanks.

Esra

**Jorgen** · 2006-08-01, 18:26

Are the body forces the same everywhere? If so, then you can use the *DLOAD command with for example the BX specifier.

If you apply periodic BCs for the displacements, then, depending on what you are trying to do, you might not need any "special" body force terms.

- Jorgen

**FYPNoddy** · 2010-01-28, 13:36

Hi,

Everyone here seems to understand how to implement periodic boundary conditions to a unit cell but i am still confused. Could someone please explain this to me in more detail.

Thanks,
FYPNoddy

**Jorgen** · 2010-02-04, 20:31

Periodic BC simply means that the deformation on the left size has to be the same as the deformation on the right side, etc.
That is, if the unit cells are put side by side there should be no gaps.

-Jorgen

**thisispeace** · 2011-01-21, 14:23

Originally Posted by Jorgen

I agree, the *Equation command can be used to create periodic boundary conditions.
I have used it many times in the past, here's an example showing the compression of a foam cell:

- Jorgen

So per pair of nodes in 3D, you equate each degree of freedom? Does that usually give you a few hundred constraints?

I'm working with a honeycomb unit cell.

**charmis** · 2011-07-28, 09:30

do u know about this error?
''in keyword *EQUATION, file "dssrtn-mod.inp", line 21607: The keyword is misplaced. It can be suboption for the following keyword(s)/level(s): assembly, instance, part''

**charmis** · 2011-07-28, 09:33

anyone knows about this error message,.,.?
''in keyword *EQUATION, file "dssrtn-mod.inp", line 21607: The keyword is misplaced. It can be suboption for the following keyword(s)/level(s): assembly, instance, part''

please let me know

thanks