Doing a 2d analysis, moving mesh in xy plane causes displacement prblm

[linkij]

Hello all,

I've been working on a beam with holes on each side, the whole part is somewhat shaped like a bracket "[". I've posted on here about it before but this is a different question. I have been applying an equal pulling force on each end of the part. The part is also completely symmetrical bilaterally. My problem is this: I want to see a bend in the optic symmetrically right down the middle when viewing the deformed image. But instead I get a part that is slanted to one side. I try moving the entire mesh around in the xy plane, and it actually alters the displacement magnitudes at the nodes. What should I do?

 

[ESPcomposites]

How are you "grounding" the model in space? This could be your problem.

Brian

http://www.espcomposites.com

 

[linkij]

I do not know what you mean. How would I do that?

 

[ESPcomposites]

So you are just applying an equal and opposite force to the model? If so, you will get some amount of rigid body displacement/rotation due to mathematical roundoff in the solution. In fact, it would be an ill conditioned matrix, but many solvers try to "help" you with that, you did not specify the solver.

If you are not sure what in the first post, then it is likely you did not ground it. You can either use symmetric boundary conditions, try grounding just a single point (or a few points) that you don't expect to displace, or add some "soft springs" to stabilize the part in space.

Brian

http://www.espcomposites.com