How to Create the Optimization Model

The creation of a bead optimization setup using the Tosca Structure.gui (GUI) is described.

This page discusses:

The following describes the general procedure for the definition of an optimization task. These procedures are supported by the task manager in the command tree in Tosca Structure.pre (GUI). The analysis model must be completely defined in advance.

Analysis Model

  • Question: Which file(s) contains the FE- model for the optimization?

  • Procedure: Link file(s) to optimization task.

    • In GUI: Select Command > FEM_INPUT and choose your model file.

Design Area

  • Question: Which surface area of the FE model should be selected regarding bead optimization?

  • Procedure: Assign node group with surface nodes to design area.

    • In GUI: Choose or define the node group with the surface nodes of the selected design area GROUP_DEF Command and define the design variables DV_BEAD.

  • Question: Are there nodes in the design area that are subject to certain restrictions? How can these restrictions be described?

  • Procedure: Define design variable constraints for node group. For sensitivity-based bead optimization nodes must be constrained in maximum positive and negative displacement.

    • In GUI: Choose or define node groups with common restrictions (GROUP_DEF). Define the restrictions using DVCON_BEAD.

  • Question: Are there certain symmetry conditions that should be fulfilled?

  • Procedure: Create a symmetry coupling condition.

    • In GUI: Create a LINK_BEAD condition and reference it in a restriction command (DVCON_BEAD).

      Note: LINK_BEAD is not supported by sensitivity-based bead optimization.

Objective Function

  • Question: Which terms describe the values to be optimized? Should these values be minimized or maximized or otherwise combined?

  • Procedure: Choose terms for optimization (design responses) and target.

    • In GUI: Define the design response (DRESP) and assign it to the objective function (OBJ_FUNC).

Constraint

  • Question: Which design response describes the constraint? Which value should the constraint have?

  • Procedure: Choose term for constraint and set target value or upper/lower boundary.

    • In GUI: Define the design response (DRESP) and assign it to the constraint (CONSTRAINT).

Optimization Task

  • Question: Are all command definitions listed above complete and ready for the optimization job?

  • Procedure: If necessary, complete any additional required definitions and prepare the optimization job.

    • In GUI: Reference all definitions above in OPTIMIZE.

Stop Condition

  • Question: Should the optimization stop after a number of iterations (or certain other conditions)?

  • Procedure: Define a stop condition

    • In GUI: Select Command > STOP.

Check Run

  • Question: Would prior testing of the restriction definitions be useful?

  • Procedure: Apply test displacements

    • In GUI: Select Command > TEST_BEAD.

Completion

  • Question: Has all the required data been specified?

  • Procedure: If yes, finish the definition of the optimization problem and save your definition.

    • In GUI: Save as <jobname>.par.

The definitions for the optimization job are assembled in a parameter file. The exact syntax of the commands can be looked up in the commands manual. The following figure shows an overview of a standard optimization task and the relation between the several commands. Only commands which are referenced in the OPTIMIZE command will be included in the optimization.