...
For a Retransition to a NURBS-Geometry a non-intersected optimisation result is needed. Therefore, the Smooth-Geometry from the Post Processing can be transferred to the model Pre Processing. The geometry of this file stays always inside the Design Spaces limits except of the Interface areas, they intentionally exceed the Design Space limits to enable an easy and clean Boolean Intersection.
...
If the default conversion option “NURBS” is activated, the Retransition back to a NURBS-Geometry (CAD) runs automatically. In this case please continue with Step 2.
If the conversion option “Facet” is activated, the Facet-Geometry is transferred to the Pre Processing.
With the Facet to NURBS Tool in the Geometry Edit Tools the STL-file can be transitioned to a NURBS-Geometry. Therefore, the Automatic Size Calculation and the Partition Preview can stay active. The NURBS Face Density influences the number of patches merged together to one bigger patch. A low density value means that fewer, bigger patches and a high density means that more, smaller patches are created.
With the middle mouse button (MMB) the operation is executed.
In a first step a preview of the partitioned quad mesh is shown.
If the partition looks satisfying the NURBS patch creation can be started. If a higher precision is desired the NURBS Face size can be varied manually. To change the size of the patches the NURBS Face Density can be modified.
When the transition is finished, the status bar in the bottom left displays “NURBS is created based on partitioned Facet Body” and a new solid shows up in the model tree.
From time to time and depending on the geometry some NURBS patches might fail. These will be displayed in the status bar as well. If this happens the geometry can be repaired manually. How this works is described here.
Step 2: Geometry Cleanup
...
To create the final NURBS-Geometry all functional surfaces and sharp edges have to be created with Boolean Operations. The best way for this is a Boolean Intersection between the retransitioned optimisation result and the Design Space of the optimisation.
Activate the Retain Original Bodies option to keep the Design Space.
...
The result is an intersected CAD-Geometry with all functional sharp edges and surfaces. At this point it is also possible to create Machining Allowances on functional surfaces if a geometry was not already created directly during the optimisation.
The finished Geometry can be used in any CAD software and for all further steps like a FE-Reanalysis with MSC Nastran.
...
Alternative Workflow
Alternatively, the option “Map LBCs and Material” can be chosen in the “Transfer Design Candidate to pre processing” Button settings. This is automating the process described above but doesn’t stop after the intersection. Additionally LBCs and Material information are mapped to the Design Candidate for a verification with MSC Apex (FE-Reanalysis). These extra steps don’t take too much time but all in all the process is running through automatically.
...