Processing of groups

In order to restrict the isocut and/or the surface calculation to certain areas of the model, the user may specify the groups of elements that should be used. The groups are read from the ONF file specified by the parameter GROUP_FILE. Then, the group names defined in the file, and, additionally, the group ALL containing all elements, can be used as values of following parameters:

Important:

Operations with groups are not supported in Tosca ANSA® environment.

  • GROUP_EXCLUDE: the elements of the group are ignored for all operations;
  • GROUP_INCLUDE: the elements of the group are marked as normal and are used for the (iso)surface calculation;
  • GROUP_SURFACE: the surface of the elements will be calculated even if they would be deleted or cut otherwise.

Any number of these commands can be specified. If an element belongs to several groups mentioned in the commands, the last command applies. For example, in order to restrict the isocut to a single group MY_GROUP, following parameters should be specified, in the following order:

    GROUP_EXCLUDE = ALL
    GROUP_INCLUDE = MY_GROUP.

Group names are case insensitive.

Important:

The ONF group file must be compatible with the model file. In case of adaptive calculations, the ONF group file should be updated using fem2onf applied to the FEM file for the required iteration.

Support of group operations in Tosca Structure.gui is limited. Using Tosca Structure.smooth screen, the ONF group file should be loaded first, so that the group names appear in the combo box to the right. After choosing a group from the list, it is possible to restrict the operations to it (by checking plot radio button) or to remove it from the model (by checking "delete" radio button). In Tosca Structure.pre screen of Tosca Structure.gui, one can only choose one group to restrict all operations to. All further group operations have to be input manually.

Example

The example shown in figure below contains two design regions DESIGN_ELEM1 and DESIGN_ELEM2, the first being the lower part of the model and the other one the upper part. Using group commands, various results can be obtained, as shown in the figure.

(no group operations, complete model)


GROUP_EXCLUDE = all GROUP_INCLUDE = DESIGN_ELEM2 (upper part only)


IGROUP_EXCLUDE = all GROUP_INCLUDE =DESIGN_ELEM1 GROUP_SURFACE =DESIGN_ELEM2 (lower part and the surface of the upper part)

Groups are also used at another place: Restricting the output to certain nodes. 

      ND_GROUP = node_group

This command removes elements from the smooth output that contain nodes not present in the specified node group. This is especially handy for shape optimizations if you would like to get the output only for the design area or the mesh smooth area.