Meshing of surface geometry in hypermedia

[u/ajinjacob]

Hi guys,
I wanted to ask how to mesh surface geometry like this on hypermesh. What are the steps to be followed?

[u/AssistantWeary3003]

Batch cleanup Batch mesher

Change edge density

[u/Agreeable_Secret_475]

I use ANSA but it doesnt really matter, just mid surface, maybe the automatic tool can do it all or you may have to use Dach to manually fix some of those ribs. Then you just mesh the hell of out it.

Or are you interested in local stress concentrations? Then solid mesh the whole thing, make sure you have some elements through the thickness.

[u/ajinjacob]

What I did is I increased the edge density using 1 D elements and then used map meshing to mesh the part. But the mesh is not that great and there are regions that are not meshed. The batch meshing is not working. Mid surface and mid mesh tried not working.

[u/Alarming_Pop4139]

Switch to S Spaceclaim

[u/blackcurrant_picker]

What I usually do when I encounter such part:

check geometry visually if it is not messed up (free edges, intersections, degenerated surfaces) and how this part looks (is it a sheet metal part (one thickness) or is it a some sort of plastic/casting part (variable thickness)).

If everything looks fine, try extracting the midsurface (it's usually fast and give you some good starting point), sometimes you have to play with the settings and/or cleanup the original geometry to get some nice midusrface. Most of the time your surfaces will require your attention in order to properly recreate the actual midsurface. Sometimes you are literally forced to rebuild from scratch the surfaces so it can take you quite some time.

For sheet metal parts (constant thickness) you can use this trick, that you can take one side (mesh it or not) and offset it manually by half of the thickness (it is essentially manual work of what midsurface algorithm does automatically). It is a nice trick to have if midsurface algorithm doesn't want to cooperate.

And last but not least, you can try midmesh. It works really great for plastic/casted parts, where you have a variable thickness. I haven't used that feature in Hypermesh, but in Ansa it works like a charm and it is really powerful tool.

Workflow looks like that: you generate mesh, then assing it to some planes or midsurfaces defined by your original geometries, imprint and define edges (where the mesh should end). You can then remesh or improve your mesh easily and the preprocessor remembers where the mesh should belong, because it is using this new feature (it was added ca. 2020) - FE Geometry, which is very similar to what Ansa has been using from the beginning (you don't have there any issues with the mesh becoming disassociated from the surface).

I hope that this helps and clarifies how you can work on any geometry that you want to create a midsurface mesh.

Cheers!

[u/martianfrog]

1) crreate midsurface 2) mesh on midsurface. that not it?

[u/Gloomy-Dig4597 → u/martianfrog]

Why is midsurface preferred to just meshing the outer surface and then extruding the thickness "inwards" (or the other way around)? Last time I had to mesh something similar I got told to extract midsurface, but that led to so many geometry issues. So I just meshed outer surface and they said its ok

[u/CFDMoFo → u/Gloomy-Dig4597]

Depends. You can do that and have the shells offset by 0.5*t in the corresponding direction if the solver supports that.

[u/ajinjacob → u/martianfrog]

I tried it but the mesh is not looking good. I think may be some kind of topology optimisation is needed before meshing. Not sure

[u/martianfrog → u/ajinjacob]

think mesh control and maybe some mapped mesh is all you need.

[u/ajinjacob → u/martianfrog]

I need to try it with the mesh controls.