Node and Element Groups

Node and element groups are required to define design variables, constraints, and objectives. They are explained within this section.

This page discusses:

Node and element groups are defined in the Abaqus input file as following:


*NSET, NSET = <setname>
*NODE, NSET = <setname>
*ELSET, ELSET = <setname>
*ELEMENT, ELSET = <setname>

These groups are loaded from the Abaqus input file during the preprocessing of the optimization execution. These groups and their group names are available for the definitions applied in the parameter file along with the groups ALL_NODES and ALL_ELEMENTS. If node and element groups with identical names are defined in the Abaqus input file, the extensions _NODE and _ELEM are added to the distinguish group names during importation. This guarantees that each group is identically identified by SIMULIA Tosca Structure.

Blanks in the group name are ignored during the import in SIMULIA Tosca Structure.

Generally, the groups that are required for definition of the optimization area should already be defined in the Abaqus input file and be used in the parameter file without using a redefinition.

Examples

File ex1.inp (group definition in FE input file):


...
*ELSET, ELSET=DESIGN_ELEM, GENERATE
1, 10000, 1
15000, 20000, 1
...
File ex1.par (apply group in parameter file):
...
DV_TOPO
 ID_NAME  = dv_design_elements
 EL_GROUP = design_elem
END_

or 


...
*ELSET, ELSET="Design Elements", GENERATE
1, 10000, 1
15000, 20000, 1
...
File ex1.par (apply group in parameter file):
...
DV_TOPO
  ID_NAME  = dv_design_elements
  EL_GROUP = "Design Elements"
END_

Selection of Properties and Materials

Important:

It is impossible to do material or property selection when using SIMULIA Tosca Structure in connection with Abaqus as properties in Abaqus do not have independent names or IDs and these are always assigned to a particular element group. Therefore, it is recommended that a selection is based on the assigned element group and not on the selection of a property.

Abaqus assigns material definitions with own names. SIMULIA Tosca Structure allocates an ID for the material definition that runs sequential starting with the number 1. SIMULIA Tosca Structure can either select material by name or by ID. However, it is recommended that selection is done using a name to avoid any dependency on the position of the definition within the input file.