Hgroups allow you to create and maintain hierarchical (tree-like) dependencies between groups. The Group menu on the menu bar has been updated to include “Extras>Hierarchy” through which this capability is made available. The group, subgroup and element parent/child relationships provide a general tool for subdividing large models. This capability has been implemented to integrate with CATIA file imports that have matching parent/child structures.

Unless a hierarchial group structure is created, the group structure is flat. All groups exist at the same level:

Complex and large FEM data models are diffcult to handle in a flat structure.

Organizing the data hierarchically establishes associations between groups that support performing operations on more than one group at a time.

Establishing hierarchical groups, subgroups and element parent/child relationships provide a general tool for subdividing large models. It allows the same operations to be performed on collections of groups, and groups and their subgroups.

Hierarchy groups contain pointers to real groups. By selecting parent groups for operations, the operations can be performed on the elements in the group and subgroups, as well.

You can perform the following actions:

At any time, you can view the existing Hgroups and group hierarchy.

Select the action “Create” on the Group Hierarchy form to display the Create Group form.

You use this form to create an association between a standard group and an Hgroup that will contain the standard group. Assigning the Selection Group name identifies the standard group that is to be associated with the Hgroup. You can either select a group from the list of groups displayed on the form or you can enter the name of a standard group. The name you specify can identify an existing standard group or it can be the name of a standard group that has yet to be created.

As an example, assume the following very simple example where you want to create two Hgroups called fem and geom. The fem Hgroup will be associated to a group containing all the finite elements of the model and the geom Hgroup will be associated to a group containing all the geometry. In addition to that, the fem and geom Hgroups will contain multiple sub Hgroups associated with groups containing only portions of the fem or geom Hgroup entities, respectively.

To create an Hgroup/ group association:

For this example, Hgroups will be used to divide the FEM and Geometry into two groups.

Creating the fem Hgroup

Repeat the process for the Hgroup called geom associated to the group called all_geom.

These actions associate real Patran entities with Hgroups and sub Hgroups. Performing post, modify, and delete operations on the Hgroups and sub Hgroups will have direct affects on the Viewport and the current state of the model.

Entities (subelements) are added to an Hgroup using:

An easy way to exclude data from a group is to:

Use the Parent icon form to add the subelement to the Hgroup. First, select the parent Hgroup. Then, click Apply on the Parent icon form. Continuing with the previous example, we would like to add a sub Hgroup under the geom Hgroup to furthur refine the hierarchy. The geometry of the model contains two surfaces. We will create two sub Hgroups under the geom Hgroup, each associated with one of the surfaces of the model. Similarly we will create two sub Hgroups under the fem Hgroup each associated with the elements of the particular surface. Thus if you post the fem Hgroup and all its sub Hgroups, you will get all the fem posted and ikewise, with the geom Hgroup for posted geometry. If you select the sub Hgroups for posting, then only those entities assicoated with them are posted.

This operation can then be repeated for creating (sub) Hgroup surface.2, associated with group surface_2, which contains entity Surface 2 where the Parent Hgroup is geom. The operation can then be done two more times, once each for creating (sub) Hgroup FEM_surface.1 and FEM_surface.2, associated with groups fem_surface_1 and fem_surface_2 each containing the finite element entities associated to the two surfaces, respectively, and each having the fem Hgroup as their parent Hgroup.

In this example, when both surfaces have been defined as subelements (sub Hgroups of the parent Hgroup), the group hierarchy will look as follows:

The following form is used to display all or parts of the hierarchy tree in the Viewport:

The following form is used to:

An additional icon, the Modify icon, is available on the Group Hierarchy form when the Action is Modify and is used to perform the initial step of a modify operation.

Always start a modify hierarchical group operation by clicking the Modify icon.

For example, if the operation is to change a group name:

If the hierarchy operation is to add members to a group:

If the hierarchy operation is to change the hierarchy strucutre:

Of course, these operations can be combined.

The following form is used to remove the association between standard groups and Hgroups.

Use the checkboxes at the bottom of the form to scale the delete operation. You can delete the entire tree by selecting Group Hierarchy.

Note that deleted items can be restored by:

Use the following form to change the current Hgroup. To change the current set:

Exporting and importing files is particularly useful for:

Use the following forms to export and import group hierarchy definitions. Use the Select Session File option on the Export form to create a snapshot by assigning a name to and saving a hierarchy definition as an export file. To import a saved session file, select the Select Session File option on the Import form.

Using the group hierarchy technology explained in the previous section, you can import a CATPart or CATProduct tree structure from a CATIA V5 document into an Patran group hierarchy. See Importing the CATIA V5 Tree, 129.