Create Trimmed Brep Surface in C#

Hi,

Could anyone help with creating a trimmed surface via C#?

My problem with using the GH components available is that too many control points are created and I would like to have some manual control to limit this if possible.

Below is an image of the result of the trim using GH components. (Ellipses are projected onto a curved surface and the original curved surface is trimmed)

I would prefer to have something like this:

The reason this is important for me is because I am subsequently exporting the surface as iges and meshing it externally for use in FEA and the current resulting mesh has far too many faces.

Any help is much appreciated!

Thanks,

Sam

Replies to This Discussion

Permalink Reply by Sam Gregson on August 17, 2015 at 7:06am

sorry images were not attached properly. Here they are attached:

Attachments:

current.PNG, 6 KB
required.PNG, 6 KB

Permalink Reply by peter fotiadis on August 17, 2015 at 11:35am

I'll post a small tutorial on that matter tomorrow (unless some other good Samaritan provides a similar thingy).

To clarify: you have a list of surfaces (open, closed, whatever) and a list of closed curves, right? and you want to cut holes on these surfaces (say by "subtracting" extrusions [breps] blah, blah), right?

Permalink Reply by peter fotiadis on August 17, 2015 at 1:08pm

BTW: Roughly speaking is this mesh "res" acceptable? (using Daniel's MeshMachine to control the mesh out of the trimmed surface [= brep]). If yes get the MM ASAP.

More tomorrow.

Permalink Reply by Sam Gregson on August 18, 2015 at 5:19am

Hi Peter,

Thanks for the reply.

Yes, your description of the process is correct.

I have come across MeshMachine before, but for these purposes I would ideally like to use the 3rd party meshing software using the Nurbs surface I have created in GH.

The reason for this is that the 3rd party software is more flexible and is more suitable for creating good FEA ready meshes. It is fast and has a good quad mesher. The only problem with it is that it uses the vertices defined in the nurbs surface (as far as I can tell) and so the solution is heavily dependant on the control points.

So I would preferably like to sort out the control points in my nurbs surface rather than mesh in GH.

Permalink Reply by peter fotiadis on August 19, 2015 at 12:05am

OK, I'll post the tutorial C# as soon as ...er... the particular workstation used for the def is ready (had "some" issues and I'm assembling a new one > your def is in some disk among a myriad of cables, zip-ties, CPU coolers a Quadro K4200 with a broken clip and ... hmm ... a motherboard [without manual] that doesn't fit to the new case).

PS: In the sequence captured I've used another approach : extrude the profiles into breps and then split the brep ["surface"] against each of them: way faster and appears that Daniel's stuff works "better" on the resulting brep [trimmed surface].

Permalink Reply by Sam Gregson on August 19, 2015 at 4:10pm

Hi again peter,

Thanks for your response so far, I really appreciate it. I think I have found a solution anyway. Exporting my Brep as a .stp file rather than a .iges file seemed to do the trick purely due to the way the 3rd party software handled the Nurbs surface.

For anyone who is interested I am using Gmsh to do my meshing and have found it very good so far and would recommend it for FEA meshes.

Permalink Reply by peter fotiadis on August 20, 2015 at 4:19am

Hi Sam

Still that dead meat odor around: that motherboard refuses to fit (because H/P did unspeakable things in the way that CPU coolers are hold in place). An ultra custom bracket is required (I'll make it soon from Plexiglas).

In the mean time can you post a "typical" case of yours? (to test the C# promised when that @$#@$# workstation lives (?) again(???))

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