Open holes on a curved surface.

Hi everyone, I am facing some issues trying to open some circular openings on a curved surface (cylinder-like). I have tried to follow some online tutorials (see attached link) but it did not work https://www.youtube.com/watch?v=y5n_hIZ96kc. In more detail I need to convert the resulting surface in a mesh so that I can later import in in GSA so that I can run a structural analysis. For some reason I cannot make it work though. When I bake the model into GSA the hole are not there. I have been using Grasshopper for just 5 days now so my mistake could be really simple. Anyway, any advice would be much appreciated since this is a part of my dissertation that is due in a couple of weeks. Thanks in advance.

Attachments:

Surface difference.gh, 10 KB

Replies to This Discussion

Permalink Reply by Joseph Oster on August 2, 2016 at 11:55am

Just 'Flatten' the 'B' input to 'SDiff'?

Attachments:

Surfacedifference_2016Aug2a.gh, 11 KB

Permalink Reply by Georgios Drosos on August 2, 2016 at 12:04pm

Thanks a lot Joseph. Could you also let me know how could I get rid off the other half of the sphere that is inside the cylinder?

Permalink Reply by Joseph Oster on August 2, 2016 at 12:08pm

Right, was just about to post a follow-up showing clean holes, without the hemispheres.

Attachments:

Surfacedifference_2016Aug2b.gh, 12 KB

Permalink Reply by Georgios Drosos on August 2, 2016 at 12:29pm

Thanks a lot for the immediate and accurate response.

Permalink Reply by Joseph Oster on August 2, 2016 at 12:39pm

Instead of intersecting spheres, you might want to intersect cylinders, which is effectively the same as projecting circles using the frame normals. Note the difference in areas between the two methods.