how to impose boundary condition along a line in 3D problems?

[Ziyu]

Hi all,

I am trying to impose a Dirichlet boundary condition for a tire model. What I want to see is that all nodes along the central line of the inner surface of the tire are fixed. So basically, I need to impose conditions on these nodes along a 2D circle in a 3D model. Attached is the input file. But it seems like CBOU with sub-command LINE cannot work in 3D, so when I plot the boundary condition using PLOT, BOUN, no node on the circle is shown to be fixed. Is this a bug or is my input wrong somewhere?

Thanks,

Ziyu

[Ziyu]

Well, I kind of solved this issue by using CBOU plus SURF with restraining the surface to a very narrow band which covers the circle. But still, I am curious about the capability of CBOU, LINE in 3D because the code seems to indicate that it should work...

Ziyu

[Prof. R.L. Taylor]

There is a polar option you can use -- needs to be added to the manual

EBOU
   POLAr x0 y0
     1  ri  1 1 1

where the '1' is a marker and ri the radius and 1 1 1 fixes all 3 dof's

All nodes at radius ri with center x0 y0 should be fixed.