Loads and Boundary Conditions

Within this section supported loads and boundary conditions are discussed.

Load Cases

SUBCASE is the default load case statement for SIMULIA Tosca Structure. SUBCOM allowed only for controller-based algorithms.

Important:

The iterative solver should be avoided for sensitivity-based algorithms because of additional pseudo loads usually.

Supported Boundary Conditions

SPC, SPC1, SPCADD, SPCD

Contact Boundary Conditions

Linear contact conditions (SOL 101) are permitted in the analysis model for controller-based topology, shape and bead optimization. Contact definitions with BCPROP can be used for shape and bead optimization, but are not allowed for topology optimization (as element properties are changed).

Defining a contact surface directly on the edge of the design space is allowed in topology optimization. The shape optimization algorithm has to be inverted (see command OPT_PARAM, parameter SCALE) if the design edge belongs to a contact surface in shape optimization. Convergence difficulties in the FE analysis may arise in cases of complex contact problems due to large changes in the model during optimization.

Node Restrictions for Shape Optimizations

Node fixations are not loaded when loading the analysis model. The boundary conditions (SPC = NR1 and SPC = NR2) are transferred to the optimization model by entering the command

OPTIONS
 READ_BC = ID, NR1, NR2 (or ALL) 
END_

When the optimization boundary conditions have been written into a separate sub case then the Main SPC number can be specified which has been entered in the CASE CONTROL SECTION of the analysis bulk data file. All SPC commands that are linked in the MSC Nastran® input file with SPCADD are also transferred to the optimization model. Specification of the sub case number itself is not permitted.