What is the difference between VGLUE and VADD ?

[Maevius]

Hello,

What is the difference between VGLUE and VADD command? I've read Help file and I know that VADD creates new solid volume and VGLUE merges volumes, but maintains their individuality. In both cases newly created volume is treated as one solid volume, so what is the difference between them in practice? When should I use VADD and VGLUE?

Regards,
Maevius

 

[meshparts]

"in both cases newly created volume is treated as one solid volume" - Not true!

VGLUE works only for volumes with intersecting areas. The volumes remain separate.

VADD works for volumes with intersecting volumes too. The result is one volume.

Regards
Alex

 

[cbrn]

Hi,
the first part of your statement is correct, but the second is not: VGLUE won't "condense" the two volumes in one only. The two volumes remain separate, but their surfaces will be "divided" in the common area(s). When you mesh two glued volumes, the mesh in the common area(s) will be compatible (i.e. nodes are in the same locations), though not united unless you perform a "merge nodes".
The best you can do in order to fully understand the booleans, and this case in particular, is to model two very simple volumes (two blocks for example) and play with the booleans.
You will notice that you can not VGLUE if there is a common part of volume: you can only VGLUE if the common part is a surface.

Regards

 

[Maevius]

Ok, that is clear for me. But if I have two glued blocks with common area and I mesh it, put constraints on and some force then during calculations these two blocks are treated as one solid object. And it is so also if I have two blocks added (I checked it). So for calculations it doesn't matter if blocks are added or glued. Of course using VGLUE I can assign two diffrent materials.

Am I right now ?

Maevius

 

[meshparts]

The difference from your point of view is that, with VGLUE you can assign different materials to the 2 volumes, whereas with VADD you can not.

PS: Assigning materials must occur after gluing.

 

[Maevius]

Ok, now I understand it.

Thank you for help.

Maevius