In SIMULIA Tosca Structure
combination of values can be performed in several ways:
- The simplest way to combine terms is using a weighted sum for the objective
function, or using a MINMAX formulation with the different
weighting of the design responses. See Objective Function for more
information.
- Combining terms may also be done using an operator - a special design
response (DRESP)
of the DEF_TYPE = OPER. This should only be done with
caution to avoid meaningless optimization tasks. You must also be aware
of the difference in the way sensitivity and controller-based algorithms
handle the operator. Note that for weighted sums you may as well use
the formulations used in Objective Function.
- Values of one type from several load cases
can be combined directly using load case
selection and weighting for the design response (command DRESP,
item LC_SET).
- Values of one type at several locations (nodes, elements) in the
model can in general be combined directly using group operations for
the design response (DRESP
item GROUP_OPER).
If several of these possibilities to combine values are applied, SIMULIA Tosca Structure
operates as follows:
- The value over all entities of the group for one load case
is calculated. This means that a loop over all entities of the group
is executed and then the value of the inner loop is calculated with the
operator specified in GROUP_OPER parameter. If the operator
is not defined by the user, a default one will be used.
- This value (already combined for the group entities) is calculated
for the different load cases
specified in the LC_SET parameter. If no LC_SET
parameter is present, then all load cases
and sub-steps (frequencies) will be used to determine the value.
- Combination of design responses by operators is applied next.
- Finally, the combination of design responses in the objective function
is applied.
|