Setting Shell Properties

One of the key shape feature types is the "shellable" feature. This is a material volume that you can apply a wall thickness to, thus defining an internal boundary and creating an internal spatial volume.

The Shell Properties command assigns a wall thickness to an active body, making it hollow, thus making the Shellable volumes hollow that are in the body. The command not only specifies the wall thickness, but you can also use it to remove one or more faces from the shelled volume, as shown in the following image:

All removed faces can be restored and the wall thickness can easily be changed at any time by using the Shell Properties command . In addition, you can specify different wall thicknesses for each face.


Wall direction

From R16 onwards, you can specify whether the thickness is an inside thickness or an outside thickness in Wall Direction while editing the shell property. The default will be inside thickness, and the default value will be 0 mm.


When an "Inside" wall direction is specified, the third tab name becomes "Core". When an "Outside" wall direction is specified, the tab name becomes "Cavity".

When you specify "Inside" wall direction and 0mm thickness, the shellable features generates the outside with the positive volumes and no core will be removed.
When you specify "Onside" wall direction and 0mm thickness, the shellable feature generates the inside with the negative volumes and the part disappears from the screen.

If you select several faces, note that clicking the icon displays the Faces to remove dialog box that allows you to:

  • View the list of all of the selected faces

  • Remove any face clicking the Remove button

  • Replace any face using the Replace button and selecting a new one in the geometry or the specification tree.

After a shellable volume is shelled, only features that have behaviors that function within internal volumes, such as ribs, can penetrate the shell (or internal) boundary. Thus, features such as boss and reinforcement cannot penetrate the shell because their behaviors are to add material volume to the outside of another material volume.

Shell Update Assistant

In some specific cases, the application cannot create non-offsetable surface in the shell computation. An error message then appears informing you that the resulting geometry cannot be assembled. These errors are difficult to manage by the user because they generally involve several shellable features and the shell properties. The Shell Update Assistant is to help the user identify the cause of an update error in the shell computation and then to solve the error.

Core (Specific to Inside wall direction)

The Shell Update Assistant is a new tab, labeled Core, that is added to the Shell properties dialog.  It displays the list of shellable features and how each contributes to the inner shape of the shell. In case of an update error in the shell property, the Shell Update Assistant allows the user to quickly identify which shellable feature(s) caused the error, to activate or deactivate shellable features, to change their core contribution type, and to try another update.

There are 3 types of core definitions for a shellable feature:

  • Interconnected core: The union of the interconnected shellable features is the main input of the shell property feature that computes only one inner shape for this union.

  • Isolated core: The offset is computed separately for this shellable feature.

  • Select core: The user selects a separate body that defines the inner shape of this shellable.

Faces causing trouble with Interconnected Core option in Shell Properties
The Shell Properties using Selected Core with Core