Dear @mahdi,
The problem is due to the CAD software or export settings that were used for conversion to .3mf. The issue was mentioned before: Regions for Umesh meshing
For example, FreeCAD exports it as a single solid and Autodesk Fusion or SolidWorks can export in multibody format.
Currently, it’s not possible to combine multiple overlapping UMESHes, unless you free the space for the second one with a Boolean operation, as was shown in an example from the Advanced course.
Alternatively, you can check my latest version (27.2 KB) of the script (requires the last MeshLib version),
It allows for the production of meshes that can be merged via the --comb argument.
# First model
python FLUKA_mesh_fix.py vessel.step --reg steel
# mesh_log.txt prints: Number of nodes, elements and regions(volumes): [12450,40210,3]
Second model, prepared to be appended after the first one
Use the next free node, element and volume IDs, i.e. add +1 to each value above
python FLUKA_mesh_fix.py coolant.step --reg water --comb [12451,40211,4]
In this case, the first export will contain parts such as steel_1, steel_2, steel_3, while the second export will start from the next volume index and produce parts such as water_4, water_5, … . This is useful when you want to concatenate multiple generated .abaq files into one larger model.
Best regards,
Volodymyr