Patches Required for Boundary Conditions

Good day,

Does anyone have a sure proof way of importing patches along with the geometry into PrePoMax. I usually use Spaceclaim to save my geometry as STEP file. However, when I import into PrePoMax, the geometry does not include the patches that I need to apply my boundary conditions. For instance, when we want to create a ‘washer’ face to apply a fixed boundary condition or an arbitrary patch (see examples shown below).

I realize that to a certain extent we can use the feature “Geometry-> CAD Part-> Split a Face Using Two Points” However, this is only possible where there is already an existing vertex point in the geometry and to draw straight lines only.


You can use Part BooleanFragments - FreeCAD Documentation in FreeCAD for this purpose. Just create a sketch, select it together with the 3D geometry and use the tool.

try using IGES file format instead.

@Synt, unfortunately IGES format exported from SpaceClaim produces the same results ie. no patches

Understood; but I was trying to avoid this extra effort. It would also require creating either Compound Parts or using Contacts or Ties

Not if you just use Boolean fragments with a sketch on the surface:

The other boolean tools (used on volumes) can cause this but there are some ways to avoid that as well.

HI arnie,

You could also select single faces directly with a negative angle.
By the way, a THICK PINCELL would be useful to allow fast selection.

Yes, but it would make the edges jagged in the case of a curved (e.g. circular) patch. So it’s usually best to prepare the patches in CAD software before importing the model to PrePoMax.

I see; I will give it a try then. Thank you.

Yes, I have done it this way before, but it’s not the most efficient method and relies on the mesh edge shapes. But thank you.