How to define displacements in element coordinate system

[Alexfalkon]

Hello everybody,

I'm would appreciate if someone knows how to define displacements on nodes according to element coordinate systems.

I'm working with a shell-281 model and I have to put a symmetry to a curved line that is only defined with nodes. This is because I have updated the geometry of a previous small model and then I have reflected it so many times to do another analysis. So I have the finite element model (with nodes and elements) but without any line or area.

So the question is how to define displacements and rotations on nodes of a curved line according to the element coordinate system. I would have to put one displacement and two rotations to zero (this are the symmetry conditions as everybody knows).

I would be grateful if anybody knows how to do that (or know that it's impossible to do) because after reading the ANSYS 12.1 manual several times I haven't found how to do that.

I'm using ANSYS 12.1.

Thanks a lot in advance,

Àlex

 

[Alexfalkon]

why not answering this post? Any idea please?? anybody?¿

 

[flash3780]

Alex,
I may be wrong, but I don't think ANSYS will offer displacements in the element coordinate system. Seeing as you're dealing with isoparametric elements, I'm not sure how you would use it any way. As I recall, the element coordinate system isn't to the same scale as the global coordinate system. In local coordinates, an element would span from -1 to 1, but (for example) it could span from .125 to .438 or from -38 to 5 in the global coordinate system.

 

[Alexfalkon]

Thanks!

But... how could I define a symmetry boundary condition on a curved line? A line defined only with nodes (and elements also).

Help please.