Creating a design direction restriction

You can specify a design direction restriction for a shape optimization. You can use a design direction restriction to keep selected nodes of your model on a planar or circular surface during the optimization. The optimization displaces the main node, and the design direction restriction applies an equal displacement (either magnitude or direction or both) to the rest of the nodes in the region (the client nodes). In addition, you can specify the axes of a coordinate system (rectangular, cylindrical, or spherical) that are applied.

See Also
Creating a geometric restriction in a topology or sizing optimization
Creating a geometric restriction in a shape optimization

Context:

The mesh should define nodes that can be moved along the design direction before the optimization starts; otherwise, the mesh may become distorted when the optimization moves nodes in the first iteration. The main node can lie anywhere in the region that you select to be governed by the design direction restriction. By default, the main node is the node in the region that the optimization moves out the most (the most growth) or moves in the least (the least shrinkage). If you are trying to optimize surfaces that are in contact, you can force the Optimization module to select the main node as the node to which the optimization is applying the least growth or the most amount of shrinkage. Alternatively, you can select a single point that will be used as the main node by all other nodes.

  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 Design Direction from the list of geometric restrictions, and click Continue.
  4. From the viewport, select the faces to which the design direction restriction will be applied. For more information, see Using the face curvature method to select multiple faces.

    If you would rather select from a list of existing face 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 faces, click Done in the prompt area.

    The Edit Geometric Restriction dialog box appears.

  6. Choose whether a client node should follow the main node by moving in the same direction or with the same magnitude or both.
  7. If you chose to move a client node in both the same direction and with the same magnitude as the main node, toggle on the axes along which the movement will be applied.
  8. Select the method that the optimization will use to determine the main node. In most cases you should select Determine from most growth and least shrinkage. You should select Determine from least growth and most shrinkage only if you are trying to optimize faces that are involved in contact.

    Alternatively, you can select Region and select a vertex that will be used to represent the main node.

  9. If desired, toggle on Ignore in first design cycle (default). When the optimization starts, it assumes the nodes can be moved along the specified design direction. If the nodes cannot be moved along the design direction, the Optimization module issues a warning and tries to continue. If you toggle off Ignore in first design cycle and the nodes cannot be moved along the design direction, the Optimization module issues an error message and stops execution.
  10. Click OK to create the design direction geometric restriction and to exit the editor.