Filling up small cracks between solids

[jpolihro]

Hello All,

I am trying to align 2 solid bodies so they intersect without forming small-area faces.
Then my goal is to combine them in a single volume and avoid "cracks" or short sticking-out edges.

What is your strategy on that?

I thought of:
1) build edges that coincide with the crack edges (here is a problem, because some of these edges are curved)
2) fill surfaces
3) close all fill-surfaces and create a solid volume inside the crack like a "tooth filling"
4) combine all voulmes

Any ideas?...

 

[Theophilus]

Can you post an image? Lots of ways to attempt this. Are the voids inside the combined solid or only along the edges? You might put a plane to the side of the surface that will be joined and then extrude material up to that body to fill in extra material--and then join.



Jeff Mowry

http://www.industrialdesignhaus.com

A people who value security over freedom will soon find they have neither.

 

[jpolihro]

I will try to post an image
The voids are along the edges. If one solid is extruded, I guess it has to intersect the other but without leaving its boundaries (this will create short edges and small faces atht stick out)

 

[dgowans]

jpolihro,

I'm not sure I fully understand your situation, but you might have good results with the Delete Face command (Insert, Face, Delete). You can use this with the "Delete and Patch" (default) option checked to remove little slivers of material or to fill in voids.

May not be applicable in your situation - can't tell without a screen shot.

 

[MadMango]

Are you sure you have a model geometry problem and not some sort of model display resolution issue?

 

[jpolihro]

Thanks for your suggestion; I will try to get to a machine with SolidWorks and get a screenshot

 

[jpolihro]

Yes, I have a geometry problem. I need the volume exported into GAMBIT (a computational fluid dynamics preprocessor) and it keeps rejecting my volumes due to short edges, slivers, wrong geometry on faces etc.
All the time I do Tools/Check in SW and get no error messages from SW. GAMBIT is more sensitive though.

 

[CorBlimeyLimey]

The problem could be with the import function of GAMBIT rather than the export function of SW. SW does not (in general) have a import/export "precision" variable like some other CAD systems.

 

[MechEng2005]

Possibly a loft between the two surfaces?

 

[jpolihro]

From SW I export ACIS(*.sat) and feed this into GAMBIT. Honestly, I would LOVE to have this solved by adjusting precision var in GAMBIT. I am afraid that when I start meshing, these geom problems will matter.

Mostly I see the short edges appear between 2 solid bodies I am trying to join

 

[jpolihro]

But you're right, I have lofts betw 2 surfaces there

 

[CorBlimeyLimey]

Do you see the "short edges" in SW or GAMBIT?

 

[jpolihro]

in both, just SW doesn't complain about it.
Once I do Tools/Check/Short egdges 0.001m then they show up.

 

[Theophilus]

Whoa--that's awfully small stuff. I'd have a hard time arguing with GAMBIT in that case.



Jeff Mowry

http://www.industrialdesignhaus.com

A people who value security over freedom will soon find they have neither.

 

[dgowans]

I was wondering if this issue was related to a mesh generation package. Those edges aren't that small, but I can see where a mesher would barf on them if the overall size of the model is significantly larger.

You might just have to resort to rebuilding your geometry in a fashion that eliminates the short edges/slivers, as painful as that might be. You will probably end up with subtle differences in the geometry, but you're going to end up with an approximation of your geometry once you mesh it anyway.

Do you have any cleanup tools (merge edges, etc.) within GAMBIT? That might be your best bet altogether if the option is there.

 

[jpolihro]

Yes, I've tried the cleanup tools but they either produce new errors or warp the model beyond reasonable limits

 

[jpolihro]

here is one example where misalignment produces slivers

 

[jpolihro]

and a zoom-out of the same

 

[GregLocock]

Can't you use one part as a tool to cut the other part?

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[CorBlimeyLimey]

"here is one example where misalignment produces slivers"
Why is there misalignment? What is causing it?

Perhaps I'm missing the problem and over-simplifying, but the intersecting portions could be trimmed off with a plane or surface passing through the common intersecting points.