Creating a demold restriction

You can specify a demold geometric restriction for a topology optimization. A demold geometric restriction forces the optimized model to satisfy specified manufacturing requirements; for example, it can prevent undercuts and hollow regions in a part that must be extracted from a mold.

See Also
Creating a geometric restriction in a topology or sizing optimization
Creating a geometric restriction in a shape optimization
  1. From the main menu bar, select Geometric RestrictionCreate.

    The Create Geometric Restriction dialog box appears.

    Tip: You can initiate the Create procedure in two other ways:

    • Click Create in the Geometric Restriction Manager. (You can display the Geometric Restriction Manager by selecting Geometric RestrictionManager from the main menu bar.)

    • Click the tool in the Optimization module toolbox.

  2. From the Create Geometric Restriction dialog box that appears, enter the name of the geometric restriction.
  3. Select Demold from the list of geometric restrictions, and click Continue.
  4. From the viewport, select the region in which the demold restriction will be enforced or click Done to apply the demold symmetry restriction to the entire model.

    By default, Abaqus/CAE allows you to select all of the model. To select faces or cells, use the Selection toolbar to change the type of object that you can select to Face or Cells. For more information, see Filtering your selection based on the type of object.

    If you would rather select from a list of existing sets, do the following:

    1. Click Sets on the right side of the prompt area.

      Abaqus/CAE displays the Region Selection dialog box containing a list of available sets.

    2. Select the set of interest, and click Continue.

    Note:

    The default selection method is based on the selection method you most recently employed. To revert to the other method, click Select in Viewport or Sets on the right side of the prompt area.

  5. When you have finished selecting the geometric restriction region, click Done in the prompt area. For more information on selecting objects, see Selecting objects within the viewport.”

    The Edit Geometric Restriction dialog box appears.

  6. By default, the region in which the Optimization module checks for collisions is the same as the region in which it enforces the demold restriction. If desired, select from the top of the Edit Geometric Restriction dialog box, and select the collision check region. To avoid cavities, the collision check region should include the demold region and any cells that are adjacent to the demold region.
  7. Choose one of the following demold techniques:

    • Choose Demolding with a central plane and select how the Optimization module will determine the central plane:

      • Choose Determine automatically. The Optimization module determines the optimal location of the central plane such that the optimization adds or removes material only in the pull direction or in the opposite direction. Toggle on Prevent hole formation to prevent the optimization from removing material from the central plane.

      • Choose Specify, and click to select a point on the central plane. The Optimization module creates a structure that can be released from a mold in both pull directions away from the central plane.

    • Choose Forging (deform only in the pull direction). The central plane, the plane at which two halves of a mold meet, is assumed to lie at the back of the model and perpendicular to the pull direction. The optimization adds or removes material only in the pull direction.

    • Choose Stamping. If the Optimization module decides to remove an element from the structure, it also removes all the elements behind or in front of the element (relative to the vector indicating the pull direction).

    • Choose Demolding at the region surface to force the optimization to add or remove material only from the surface of the constrained region.

  8. Click , and select two points specifying the vector along the pull direction.
  9. Enter the Draft angle. The draft angle is a small angle relative to the pull direction that will be introduced to the optimized model to ensure the part can be removed from its mold. Normally the value is between 0° and 10°.
  10. Click OK to create the demold geometric restriction and to exit the editor.