Symmetric boundary conditions 4

[karabiber]

Hello
I have a unit cell(cube 15*15*15mm).
I have symmetrical b.conditions for this cell as can be seen from figure.

I would like to write this boundary conditions into my report.
But I am not sure how to write it. For that surface, I have XSYMM boundary conditions. I am wondering how if I can write it like this:
-u(U1=UR2=UR3)=0

It is the surface perpendicular to X axis, however, there are two surfaces perpendicular to X axis. How can I say that I put boundary conditions on the rear surface? I hope the question is clear.

 

[GBor]

Boundary conditions applied perpendicular to the x-axis at X = 0. Or, if you move it back just a bit, describe the octant that it is in relative to the origin. Or simply show the figure as you have done for us.

Perhaps I'm misunderstanding the question.

 

[rb1957]

i don't understand the pic at all ...
are you saying that the red line is a symmetric boundary ?

 

[rstupplebeen]

In my reports I usually just say quarter symmetry and assume the reader can interpret this. Since they are reading an FE report this should not be too abstract.

Rob Stupplebeen

 

[corus]

I say the same that the geometry and loads allow symmetry to be applied and include on the model picture arrows that indicate the symmetry planes, but I now mirror the results, or sweep them (for 2d) to show how they would appear in the real world. Folks understand them better that way.

corus

 

[karabiber]

rb1957:
Red-lined region.
Over there, for instance, there is a X symmetry. I am wondering how I can write it in words?

 

[rb1957]

yeah but that's my problem ... you're got a cube and you want to a symmetric BC on two 1/2 faces ... physically what does this mean ? a symmetric BC only helps reduce model size (ie the model is 1/2 of the real structure) ... what would the full model look like ??

as for describing you what you're doing, how about "the model is constrained with a symmetric boundary condition applied as shown in Figure 1" ? probabkly the next sentence should be "This is valid because ..."