Selection Criteria for Load Cases (LC_SEL)

LC_SEL is needed for combination of more than one load case or sub-step, used in the definition of a design response.

If more than one load case or sub-step is used in the definition of a design response, the question is how to combine the load cases or sub-steps. For the optimization, there is a big difference if the design response is determined for the minimum value over all load cases or for the maximum value. For example, if the design response represents the modal frequency, the minimum value will be the first eigenvalue and the maximum value will be the highest value stored in the result database. If this design response is then used in the objective function, the optimization result will be totally different.

As LC_SEL values, the following values are available:

  • MIN - determines the minimum value over all load cases/sub-steps
  • MAX - determines the maximum value over all load cases/sub-steps
  • SUM - sums up the values over the load cases/sub-steps
Important:

Depending on your design response default values for load case combination are selected. Thus, it is not necessary to select them manually.

Manual selection of the LC_SEL parameter is not supported by Tosca Structure.gui, Tosca ANSA® environment and Tosca Extension for ANSYS® Workbench.

Definition in Tosca ANSA® environment

Manual definition of LC_SEL is no longer supported. Default values depending on the type of design response are used instead.

Definition in Tosca Structure.gui

Manual definition of LC_SEL is no longer supported. Default values depending on the type of design response are used instead.

Definition in Tosca Extension for ANSYS® Workbench

Manual definition of LC_SEL is not supported. Default values depending on the type of design response are used instead.

Note:

  1. For the different types of design responses SIMULIA Tosca Structure has default settings for the LC_SEL item. All nodal based results like stresses, strains, displacements, forces, ... are used with the operator MAX. Element based results like the strain energy are used with the LC_SEL operator SUM.
  2. For sensitivity-based optimization: If a design response with MAX or MIN operator is used in the constraint or objective function definition, then SIMULIA Tosca Structure creates a new design response for each load case/sub-step, that are then used in the constraint or objective function definition. The name of the design response can be seen and tracked in the TOSA.OUT file and also in the optimization_report.csv file.