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Tutorial IV - Feature Suppression & Regeneration

  This tutorial will cover suppressing features of a feature based model and regenerating new volumes. For this example, we are using the $(UGII_BASE_DIR)/ugcast/parts/fea/fea_solid.prt file which is a model of a bracket (below). The objective of this tutorial will be to suppress the hole in the bracket.




Suppressing Features

  When a model is loaded, each volume is checked for the existence of a master model. If it exists, a folder will be created in the Structure Tree named "Features" that will contain a list of features for that volume.

  Each entry will be labeled with the name, the id number in parenthesis, and the number of children in brackets. Each of these can be expanded by left clicking on the green icon. This will display the features that are children.

Marking for Suppression

  In order to remove the hole in our example part, we must mark the "SIMPLE_HOLE" feature for suppression. This is accomplished by right clicking on this feature and selecting the Suppress toggle button in the Edit/Master Model menu. The features that are marked for suppression will have their icons grayed out.

Reverting

  The original value of the feature suppression flag can be recovered by selecting the feature and choosing Revert from the Edit/Master Model menu. The entire feature tree can be reverted by selecting the "Feature" folder then choosing Revert. The Revert function always returns the back to the value at the time the volume was created or read from file.

Regenerating

  After marking the desired features for suppression, the volume must be regenerated. To regenerate, select the volume by left clicking in the Structure Tree, then choose Regenerate from the Edit/Master Model menu. If the regeneration is successful, a new volume with the features suppressed will be created.

  The underlying CAD kernel will determine which features should be suppressed in addition to the marked features. The structure of the feature based model will determine this selection. It is possible that certain dependencies exists that will yield undesirable results or prevent the regeneration from taking place altogether. This fact should be kept in mind when attempting to suppress features of models that were not constructed to support it.

  Examining the resulting Structure Tree of the new regenerated volume (right), you can see that seven of the nine child features of "SIMPLE_HOLE" feature were actually suppressed. This was determined by the underlying CAD kernel (in this case, Unigraphics). Also note that the resulting model (below) does have the hole removed, however, the "BLEND (10)" feature was also suppressed which has changed the overall profile of the bracket. This is due to the way the part has been constructed, and due to this structure suppression of just the hole itself is not possible.


Responsible NASA Official: William T. Jones
Site Curator: William T. Jones
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Last Updated: Oct 2, 2003