Creating Variable Offset Surfaces

You can manage several variable and constant offset surfaces in one operation.

This task shows you how to:

Before you begin:
  • You must have access to the Generative Shape Morphing app.
  • Create a 3D shape containing a surface and subelements (surface or wires).
See Also
Creating Offset Surfaces

Create a Variable Offset Surface

You can create a variable offset surface.

  1. From the Transform section of the action bar, click Variable Offset .
  2. In the Base Surface box, select the surface to be offset.
  3. In the Parameters tab, select each subpart to be offset (whether wires or surfaces).
  4. In the Offset list, select the offset type for each subpart.
    OptionDescription
    Variable Applies a variable offset to the subpart. The offset value box is unavailable.
    Constant Applies a constant offset to the subpart.

    In the offset value box, enter the offset value.

    Important: If the subpart to an offset is an element such as a line, curve, or edge, you can select the offset to be:
    • Constant (Border): The element is considered as a border element. Hence, it must lie on a boundary.
    • Constant (Inner): The element is considered as a constant constraint within a variable area. Hence, it must lie in a variable area and not on a boundary.

    In the example below, a constant offset value of 40mm for Surface.1, a variable offset value for Surface.2 and a constant offset value of 20mm for Surface.3 is defined.

  5. Optional: Select one of the following:
    OptionDescription
    Replace Replaces the selected surface by another surface.
    Add Before Adds a surface before the selected surface.
    Add After Adds a surface after the selected surface.
    Remove Removes the selected surface.
  6. In the Offset law type area, select the offset law type between Linear and S type. By default, the offset law type is S type. In this mode, the extremities are tangent continuous.
  7. Optional: Set advanced parameters:
    OptionDescription
    Automatic split of variable areas Performs an automatic internal split of variable areas if required.
    Merging distance Value for the result skin hermetization.
    Angular threshold Value for result skin sharpness.
    Deviation Maximum deviation between actual result and exact result.
  8. Click Preview.

    The offset surface is displayed normal to the reference surface.

    Tip: Click Reverse Direction to reverse the offset direction.
  9. Click OK.
    One single feature is created: an automatic join of the resulting areas is performed if the result quality allows it (G1 connections).

    Important:
    • All adjacent surfaces that are tangent continuous must have the same offset value. Otherwise an error message is issued.
    • Avoid any fading edges between two surfaces that have different offset values.

Remove Sub-Elements

The Sub-Elements to remove tab helps you for the analysis in case the offset encounters a problem.

  1. Click Variable Offset .
    The Variable Offset Definition dialog box appears.
  2. In the Global Surface box, select the surface to be offset.
  3. In the Parameters tab, select each subelement to be offset (whether wires or surfaces) and define its offset type:


  4. Click Preview.
    An informative message appears and informs you that some subelements are erroneous. The geometry shows these subelements and the flag notes display the subelements to remove.

  5. Click Yes to accept the offset.
    In the Variable Offset Surface Definition dialog box, the Sub-Elements to remove tab lists the erroneous subelements and a preview of the offset is displayed.
    Tip: Both offset types apply to wires and surfaces.
  6. Optional: Use the following modes to add or remove a subelement to create the variable offset.
    OptionDescription
    Add Mode
    • Click an unlisted element in the geometry to add it to the list.
    • Click a listed element to preserve it in the list.
    Remove Mode
    • Click an unlisted element in the geometry to leave the list unchanged.
    • Click a listed element to removed it from the list.

    Important: The list of subelements to remove is updated each time an element is added. Note that if you modify an input in the Offset dialog box, the list is reinitialized.
    Notes:
    • If you double-click the Add Mode or Remove Mode option, the chosen mode is permanent, that is, successively selecting elements add/remove them. However, if you click only once, only the next selected element is added or removed. You only have to click the option again, or click another option, to deactivate the mode.
    • The availabilities of contextual commands depend contextual commands on the location where you activate the context menu, and the act only on the lines that you right-click. If more than one line is highlighted, right-clicking one highlighted line is equivalent to right-clicking all the highlighted lines at the same time. In this case, the contextual command acts on all the highlighted lines. Consider the following cases:
      • Case 1: line 1 is highlighted and line 1 is right-clicked: the selected command from the context menu acts on line 1.
      • Case 2: line 1 is highlighted and line 2 is right-clicked (but not highlighted): the selected command from the context menu acts on line 2.
      • Case 3: line 1 and line 2 are highlighted and line 1 is right-clicked: the selected command from the context menu acts on both line 1 and line 2.
      • Case 4: line 1 and line 2 are highlighted and line 3 is right-clicked (but not highlighted): the selected command from the context menu acts on line 3.

  7. Click Preview.
    The offset surface is displayed normal to the reference surface.
  8. Click OK.


Create a Constant Offset Surface

You can create an offset surface whose subelements have several constant values. The offset surfaces are automatically extrapolated or split so that they connect.

  1. Click Variable Offset .
  2. In the Global Surface box, select the surface to be offset.
  3. In the Parameters tab, select each subelement to be offset.
  4. In the Offset list, select the offset type and apply a different constant offset value to each of them.
  5. Click OK.