A new release version of the PrePoMax contains the following FEM features:
- added support for sweep meshing
- bug fixes
The sweep meshing was tested on a couple of examples. All of them could be sweep meshed with appropriate algorithm settings.
The user is supposed to select the source surfaces (one or multiple), then the algorithm determines the side surfaces and the target surface (one).
Limitations of the algorithm:
- all side surfaces must be 4-sided surfaces
- if a side surface is split into multiple 4-sided surfaces that form layers away from the source surfaces, all other side surfaces must be split at the same positions, creating the same number of layers on all side surfaces
- a periodic side surface with a single seam (a cylinder with a single edge in the axial direction) must be split at least one more time to form two 4-sided surfaces
- the target surface must be only one
Currently, the algorithm is based on topology constraints only, and no geometrical constraints are included. That may result in strange/invalid results in special cases. Some geometrical constraints will be added in the future if necessary.
In most cases, the sweep mesh algorithm can replace both the extrude and the revolve procedures.
3 Likes
Can you please upload examples for these special cases? I did some tests and also often got extremely distorted and collapsed elements, but was able to prevent this by changing some options. So I would really like to test this with the parts you mentioned.
Did you experience any problems where the meshing failed but should succeed? Or succeeds in other software?
I did not test all the possibilities; I only imagined them 
For example, consider a solid extruded profile with a rectangular cross-section and one additional division at the half extrusion length. Then, increase the size of the middle cross-section only. At some point, the start angle of 180° of the surfaces at the middle cross-section becomes so small the mesh becomes unusable. I know an experienced user will not attempt something like this, but the goal is to apply sweep messing on compound parts automatically, and then a robust algorithm will be needed that could predict such unusable cases.
Yes, with the default settings even for simple bended tube parts and coarse mesh in sweep direction like this:
It looks good from the outside but generates colabsed elemens:
I have always had good results with these settings so far (most important here’s to deactivate “Global smooth steps”):
So I was wondering if this setting might be more useful as the default setting… But that would require testing more different parts.
Ok, the global smooth steps are mainly required if the source and target surfaces are not simple filled surfaces of their edges but have a concave or convex shape.
In such cases, I could limit the smoothing to only a couple of element layers at the source and target surfaces while the global smoothing is applied to all elements in the mesh. In the case of bent meshes, the smoothing tends to move the nodes towards the bent center, as is probably the case in your example.
Changing the default setting could also be a solution.
** Edit **
The mesh optimization is part of the Gmsh 2D meshing procedures. In your case, it only affects the mesh at the source surface, so I think it should not greatly improve the mesh quality.
It definitely helps in combination (for these kind of parts) to ensure that the 2D mesh of the target surface does not deviate too much from the source surface and prevents the “unnatural” shifting of the midside nodes when “Midside nodes on geometry” is selected:
1 Like
Attached a more varied example to try out
compressed-air-gun.zip (591.3 KB) step file
*Feature request
I don’t know if this has been mentioned before, but at some point it would be handy to have a feature, where used meshing setups could be filtered, grouped or highlighted automatically by parts.
3 Likes
There was a request to highlight the base parts used to create the compound but not for mesh setup items.
So, a tool for showing dependency is needed?
Would it help if there is a possibility of creating folders and organizing the items manually? It would be a more general solution but would require some manual work.
2 Likes
Yes, in my opinion that would be an absolutely sufficient and flexible solution. But being able to display dependencies would of course be perfect!
1 Like
I am not sure how to implement dependencies. Sometimes, there are dependencies in both “ways” up and down. An item might be a parent to some items and a child to others. So which ones to show? How to show them so that when the selected item is left with the mouse the selection remains? Do we have some examples in other codes to copy ?
Well… as a user who can’t really estimate the effort involved, I could imagine that you could right-click on a part and activate the “Show dependencies On/Off” switch in order to mark the part itself in bold with all mesh settings applied to it. These would remain in bold until it is either selected again or applied to another part. I don’t know, would this already lead to parent-child conflict?
I like the idea of ​​simply creating folders more and more… 
