# Periodic boundary condition for RVE (Abaqus)

Hi,

i have a problem with the periodic boundary conditions. I want to implement the boundary condition for example

which i found it in the internet. The first equotion is u_facebuttom - u_facetop=0

So i know that we can do this with creating Constraint and selecting Equotion.

At first i define Sets FaceButtom and FaceTop which includes all nodes on bottom and top. Here is a picture for the Set Face Top

Now i want to implement it with creating a   Constraint and selecting  Equotion. My Equotion for the first boundary condition is  u_facebuttom - u_facetop=0

It looks like this:

But now if i click the OK button to finish it for the first boundary condition, i get the Error: All terms  except the first one must use sets consisting of a single point; therefore Set " face Top" cannot be used in row 2.

Can somebody explain what i have to do ?

How can i make periodic boundary conditions for my Representative Volume Element ?

Thank you for help!

edit: pics should be there now

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### If you use equation

If you use equation constraints, and want to apply periodic boundary conditions, you should create a equations constraint for each dof. So in 3D you have to create 3 (if not constraining the rotation degrees of freedom in for example shells) constaints per node set. So, first you have to find out which nodes are paired, then create a set for each node, and apply the equation constraints. Repeat for all nodes on the surface. Be extra careful with nodes in corners (and on lines in 3D).

### share one simple 3d cube working example (abaqus)

sir

i had found this while searching for pbc help and i tried running it but the result which appears is totally different from what they have given .

would u check whether the rve.inp is correct or am i doing it wrongly

thank you

### periodic BC in abaqus

Dear Friend

hello and good time!

i want to apply PBC for a cube to achieve uniform displacement and potential for edge nodes in opposite faces. i want to restrict displacement in three directions including U1,U2,U3 and also electric potential. i attached the problem below. p refers to u1, u2, u3 and electrical potential. what should i enter as DOF? is it possible to apply all this equation without subscript?

### SetByBoolean HELP

I am trying to implement PBC to 3D cube

i want to subtract the edge nodes from face nodes

my set for facenodes for one of the faces is named as FN0 and its bounding edge node set is named as EN0 EN1 EN2 EN3)

i used command to add all edgenode sets

mdb.models[name].parts[name].SetByBoolean(name='myset',sets=('EN0','EN1','EN2','EN3'))

running this command crashes my abaqus cae

could any one help me with how to deefine arguments in setbyboolean