Linear boundary with CBOUn at an angle

[Axuni]

Hi all,

I am trying to impose a boundary condition to nodes that are aligned in a line, that has a certain angle to x-axis. For simplicity I started with an angle of 45 degree.

I prepared an input file to clarify what I am trying to do and also appended the output I received with FEAP 8.4. Please neglect the solution part - my question is about the meshing/boundaries.

Analyzing the outcome it shows, that the 1. and 3. CBOU (lines 19-22 and 29-32 in input file - 1973-2002 and 2018-2047 in output file) work fine, while there are no nodes found for the 2. CBOU (lines 24-27 in input file - 2006-2014 in output file).

Could you please tell me why this is so and how to set up the boundary correctly?

Best,
Christian

[Axuni]

Sorry, I had problems uploading the files.
The files are attached now.

Thanks!

[Prof. R.L. Taylor]

The current coding cannot find nodes for lines in the interior of the mesh.  You will need to code a user module to do this.  To make sure all the mesh is there the best choice would be a "umani*.f" one.

[blackbird]

A modification of the second CBOUN to

Code: [Select]

CBOUndary           
linear 1 1           
 1 0.50 0.00         
 2 0.50 1.00

will find nodes in the interior of the mesh on a vertical line at x=0.5. Should it not be possible to do this for a line at an angle?

[Prof. R.L. Taylor]

Yes, you are correct the CSURf commands are able to plot on Cartesian lines in either the interior or the boundary of the mesh.
They are able to also do this for polar representations of coordinates.  They are NOT able to project to lines on an angle - which would be very useful.  To do this requires coding changes.