Source: Freeze & Unfreeze
The Freeze feature is an advanced modeling tool available from the Tools Menu. Freeze has two applications: it allows for an alternative method for assembly modeling with multiple body parts, and it allows you to slice a given part into several sub-volumes (for example, sweepable volumes for hex meshing).
The Freeze feature allows you to control the second step. It acts as a separator in the construction history as displayed in the Tree Outline. Any bodies created for features before a Freeze will become frozen. Frozen bodies are denoted by the ice cube icon next to a body under the Bodies branch of the Tree Outline. All frozen bodies will be ignored when it comes to the Add, Cut, or Imprint Material operation of any features following the Freeze.
Thefeature activates a selected body, or a group of frozen bodies, and merges them with the active bodies in the model if applicable.
ANSYS DesignModeler is not an assembly modeler; rather it is an “extended” part modeler that can deal with multiple bodies. However, with the and the tools, certain modeling capabilities for (imported) assemblies do exist. On the one hand, this may seem a limitation, but on the other hand, this is a different approach to assembly modeling and allows actually more (or other) functionality (for example, slicing).
By default, if you import an assembly from a CAD package, the modeling capabilities of DesignModeler are limited, because applying any form of a 3D modeling operation would simply merge any touching bodies into one. However, this can be circumvented with theand tools.
If you immediately Freeze the model after importing an assembly or import an assembly using the Add Frozen operation, your bodies will be shielded from the merge. You can, at that point, add new bodies; however, you cannot modify any of the existing frozen bodies. For this, you can use Unfreeze to select bodies to become “active.” (Active bodies are depicted as shaded blue blocks in the Tree Outline. DesignModeler can now operate on the newly unfrozen bodies as it would on any other active bodies.