# Thread: How to define this Boundary Condition?

1. Junior Member
Join Date
2007-01
Posts
25

## How to define this Boundary Condition?

Hello,

If I want to want to make a set of nodes keep same displacement (unknown) during loading, How to realize it in ABAQUS/CAE

Thanks.

2. Senior Member
Join Date
2006-02
Location
Houston, TX
Posts
136
You can do so by defining a constraint on those nodes.

Ashu

3. Junior Member
Join Date
2007-01
Posts
25
Hi Ashu,

Thank you for reply. I am still confusing
Do you mean constraint equation? I have 301 nodes on one edge and need them to have the same displacement in one direction.

if I set 2 sets: 1nodes and 300 nodes
The error is: when the first term uses a single point set, then all following sets must also be single point sets.

If I set 2 sets: 2 nodes and 299 nodes
The error I got:
All the nodesets used in defining an equation must consist of the same number of nodes, except that single-node nodesets can be used where a node number would be valid

So does it mean I have to set 2 sets: 150 nodes and 150 nodes and define another constrain to include the 301st node? And if so, will the 150 nodes in one set keep the same displacement automatically?

Is there a easier way?

4. I agree with Ashu: you should be able to create a single *Equation command that forces the 300 nodes to have the same displacement in a given direction as the 1 reference node in that direction.

- Jorgen

5. Junior Member
Join Date
2007-01
Posts
25
Hello Dr.

I am using ABAQUS/CAE,

I tried, when I make 2 sets: one with one node, the other have 300 nodes
by using: constraints/equation

The error window comes out in CAE: "when the first term uses a single point set, then all following sets must also be single point sets."

Does it mean I have to set 300 constraints, and make the displacement of the nodes equal to each other one by one?

Thanks.

6. Junior Member
Join Date
2007-01
Posts
25
Yeah! :D

It works now! After simply change the order of the two sets.

Thanks a lot!

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