Negative cast of a complex mesh

Grasshopper
1

Hello all,

I’m trying to achieve a model to use in a FEM program for a thermal simulation.
The model should consist of two closed geometries:

  • the pattern offset or thickened by 8 mm;
  • its negative cast adhering to both sides of the offset pattern.

Among the tries that I carried out until now, the most common error I noticed is that when I operate the component Mesh Difference between a scaled-down bounding box and the mesh offset with WB Mesh Thicken, 1) only one of the two surfaces of the mesh is used to generate a negative solid 2) this happens only when the scaled bounding box is below 0.30 (ca) as a scaling factor. My aim is instead, to have a solid negative filling adhering to both surfaces of the mesh + in a bigger bounding box (around 0.90/80 as a scaling factor). For the sake of the FEM analysis is important to have closed solids to be then converted into meshes.
Another aspect I would like to correct is the orientation of the offset/thicken mesh, is there a way to align its outer edges to the surface of the bounding box while still having a closed mesh?

Do you have any tips on how to work around this problem? Many thanks!
NegativeCast.gh (1.5 MB)

2

I didn’t have a look at the model (on my phone), but the new Shrinkwrap feature sounds like it might be a solution here:

3

Dear Anders,

thanks for showing me this new feature, it worked perfectly both for the negative cast I was trying to model and for aligning the outer edges of the mesh. Thank you so much for your fast reply too! I attach the 3dm and gh file with the solution.
NegativeCast_Solved.3dm (16.9 MB)
NegativeCast_Solved.gh (20.0 KB)

4

Your main problem is that your mesh is sort of dirty, it have very short edges:

2022-12-31 01_03_25-Window
2022-12-31 01_03_25-Window921×517 23.8 KB

With align, you can get a clean mesh, where offset works way better:

2022-12-31 01_01_48-Window
2022-12-31 01_01_48-Window1796×630 148 KB

NegativeCast.gh (1.4 MB)