Creating a Void (Hole) Inside a Region in THERM – How to Do Boolean Subtraction?

[Vishal Kadia]

Hello,

I am trying to model a hollow section in THERM, where only the outer thickness should be modeled as solid and the interior should be a void cavity.

However, I am unable to create a void inside an existing region. My current workflow is:

1. I import my DXF as an underlay (not auto-convert).

2. I first trace the inner shape as a polygon and assign it the material “Void.”

3. Then I trace the outer boundary as a polygon.

But when I create the outer polygon, THERM fills the entire area as one solid region and ignores the inner void. The result is always a fully filled part instead of a hollow frame.

From what I understand, there does not seem to be any Boolean “Subtract Regions” function in THERM 8.1, and the “Fill Void” tool only works when the region is surrounded not inside one another.

[Robin Mitchell]

THERM cannot model "voids" in the geometry. Those voids would need to be filled with a material such as a frame cavity. 

Robin

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Robin Mitchell

Windows & Envelope Materials Group
Lawrence Berkeley National Laboratory

[Jonathan Spencer]

Therm does not allow a single polygon to have a hollow inside of it. When you need to make a part that has a hollow, like an airspace inside of it, you have to break the polygon into multiple polygons. For a simple glazing bead with 1 hollow, you need to break it into 2 parts. For a complicated frame, it will require you to break it up more. 

It is just a limitation with how Therm works. No doughnuts. Polygons can't loop back around and touch themselves with a void in the middle.