# Thread: Periodic boundary conditions in ABAQUS

1. Junior Member
Join Date
2005-06
Posts
19

## Periodic boundary conditions in ABAQUS

Hello All;

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

Thanks.

2. Junior Member
Join Date
2005-06
Posts
19

## Periodic boundary conditions in ABAQUS

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.

3. 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

4. Junior Member
Join Date
2005-06
Posts
19

## Body Force

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

5. 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

6. Junior Member
Join Date
2010-01
Location
Ireland
Posts
7

## Periodic BC's

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

7. 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

8. Junior Member
Join Date
2010-07
Posts
1

## Nodes galore!

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.

9. Junior Member
Join Date
2011-07
Posts
2
''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''

10. Junior Member
Join Date
2011-07
Posts
2

## problem while applying periodic boundary condition

''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''

thanks

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