About Creating a Shell

This section describes the various options available in the Shell.x dialog box to create a shell.

Tangency propagate Faces To Remove

If the faces selected in the Faces to remove field have tangent continuous edges, the edges tangent to the edges of the selected faces can be taken into account. To do so, select the option while creating a shell feature. Thus, the entire faces along these edges are removed.

By default, this option is selected.

In the below example, the yellow face is selected in the Faces to remove field for creating shell feature:

The result is as shown below:

With the option selected.	With the option deselected.

Note: This option is also available for the faces selected in the Other thicknesses box.

This section provides recommendations when shelling material.

• The value for the shell must be lower by half than the thickness of the input body. Otherwise, the resulting body may be not valid due to self-intersections. To avoid problems, ensure that the input body is thick enough.
  
  
• In some specific cases, you may need to perform two shell operations consecutively. To avoid problems, the value for the second shell should be lower by half than the value of the first shell.
  
  
• If you need to shell a multi-domain body, perform only one Shell operation : select one face by domain to avoid problems. The tree then includes only one Shell feature as illustrated below.
  
  

You can ignore the troublesome faces when creating a shell.

In some specific cases, the app cannot shell the selected face. An error message appears informing you that the body cannot be built properly. After closing that window, another message appears proposing you to ignore the faces causing trouble. If you accept that solution, the shell is performed and the face causing trouble is removed.

Later on if you edit the shell, the ignored face is previewed and the Reset ignored facesoption is then available in the Shell.x dialog box.

By selecting this option, the ignored face is reinitialized and the Ignored face mention in the geometry is deleted. If the check box is unchecked, the previous ignored face is still taken into account for the next feature definition.

Ignoring faces in many cases avoids a costly and difficult laborious rework of the 3D shape.

Sometimes, you need to use the Extract option to be able to add thickness to a face.

The Extract capability lets you generate separate elements from initial geometry, without deleting geometry. This command is available after clicking a dialog box prompting you to deactivate the shell and extract the geometry. Once the operation has been done, the Extracted Geometry (Shell.x) node is displayed in the tree. This category includes the elements created by the app.

The Extract option is available if only one face was selected to perform the shell operation.