Automatic Node Group Definition (GROUP_AUTO_DEF)

This feature is especially important in relation to function-based node coupling. For example, if the rotation symmetry of a shaft shoulder loaded with a bending moment should be maintained during optimization, it is necessary to couple all nodes of the circumference. This involves a large number of node groups and node couplings.

Starting with a parent group that has been previously defined by the user, the GROUP_AUTO_DEF command can be used to automatically define child groups (children). Employing various methods, search areas are established originating at every node of the parent group. All nodes located within a search area are “captured” and collected in a child group. Thereby, only those nodes that are currently in the selection list NODES are considered. Per default, all nodes are selected at the beginning. (Thus, if no SELECT command is activated, all existing nodes are considered. You can "preselect" a certain area using SELECT to restrict automatic group definition to this area, see Selection of Objects in Tosca Structure.gui ).

Child groups are labeled with the name of the parent group and a numerical index. For example, if child groups are formed from a node group titled “parent” which contains 4 nodes, the four children groups are named “parent_1”, “parent_2”, “parent_3” and “parent_4”. Various procedures can be used to define a search area.

1. Specification of a continuous search area (SEARCH_TYPE = CONTINUOUS): All nodes located within the search area that are currently selected by the node selection list are assembled and assigned to a child group:

2. GROUP_AUTO_DEF
     ND_GROUP    = parent_group 
     ...
     SEARCH_TYPE = CONTINUOUS
     ....
   END_
   

   This is also shown in the following figure:

3. Specification of a search area divided into discrete sections (SEARCH_TYPE = DISCRETE): All nodes located within the discrete sections that are currently selected by the node selection list are assembled in child groups:

4. GROUP_AUTO_DEF
     ND_GROUP    = parent_group 
     ...
     SEARCH_TYPE = DISCRETE
     ....
   END_
   

   This is also shown in the following figure:

5. Search in various local coordinate systems (SEARCH_TYPE = CS_MULTI): The coordinates of the individual nodes in the parent group are determined in relation to a specified coordinate system. All selected nodes with matching coordinates in relation to the specified search coordinate system are assembled in child groups together with the corresponding parent node:

6. GROUP_AUTO_DEF
     ND_GROUP    = parent_group 
     ...
     SEARCH_TYPE = CS_MULTI
     ....
   END_
   

   The following figure shows the definition of multiple coordinate systems: