Starting from v2.0.2, I am just impressed how good structural meshing now works with the new Mesh Refinement for compounds. I would like to share some positive observations, using a bolt-model as example:
The CAD model is created with the shaper-modul inside salome. All volume partititions are already done here, so that the compound consists of 116 six-sided parts. For some reason this specific model must be imported as brep file to get a compound with solid-parts in prepomax, importing it as step file i only get shell surfaces.
The next observation is, for a structural hexa mesh the value for the Min element size can be higher than the later used value for a refinement. So this is only necessary for creating refinements for tetra meshes.
Using mehing_parameters with a huge value for Min and Max + Transfine_mesh (Recombine = Yes) creates a hexa mesh with one element per volume.
Next i use mesh_refinement for the shown 4 edges (alternativ the 4 faces could be selected). The detection of finding all opposite edges, where this refinement has to be projected to, works very good so that it is not necessary to select all opposite edges as well.
In the next step you can then create two element-sets for the upper and lower sections and convert them to parts to have the needed cutting-plane where pre-tension can be applied to (the remaining part is then empty and can be deleted), unfortunately this leads to losing the associativity to the geometry based mesh creation. On the other hand, when having a model with many bolts, it makes more sense for me to mesh one bolt and use the transform option to copy it several times to minimize the meshing effort, in this case the associativity also gets lost.
By creating the element-sets, in some cases the “Geometry based selection” works not always proper, means that sometimes some inner elements will not be recognized. Here i suggest to use the “FE mesh based selection > Element” instead:
The only option I would like to have is, to be able to specify the number of elements or nodes per edge as an alternative to the element size. Anyway, I’m thrilled.
In short: WB PART and surfaces created from a sketch. Then, from several surfaces, create a COMPONENT. First, select Solid, then Component, and then use the Split > Slice to Compound menu. The surfaces must be larger than the solid. I create a simple copy of the sliced ​​solids.
Sorry for errors. I meant “Compound.” For me, it’s the fastest method. There are probably other ways to do it. Be careful with clones and copies.
Apparently, the only way to avoid it is to use surfaces (e.g. Part Planes) instead of datum planes and fuse them (Part Union) or apply Boolean fragments to them, then cut with Slice apart or Slice to compound. I haven’t found a way around this with datum planes yet.
For such simplified bolt models this may indeed be sufficient. What software is that ? It could be done in a similar way in Gmsh starting from circular faces.
for modeling of single bolt w/o array operations this manual approach still can be okay, but maybe not for complex large assembly. Connector parts of bolt and welds are commonly used in real world applications, unfortunately is lack feature in FE software. Some programs provide such as Catia, PTC Creo and Ansys with external plugins.
If I have a choice in PrePoMax between more features for creating a 3D CAD model or expanding the FEM calculation part, I choose FEM. One person can’t do the entire program correctly and error-free. It’s better to introduce beams and trusses instead of creating CAD. For CAD, there’s FreeCAD, and a team of people there is working on it. PrePoMax is great and is working better and better. Bravo to Matej
Great respect to Mr. “FEAnalyst” for maintaining this forum, devoting a lot of time to helping others and participating in the creation of the program
