Workflow

For the consideration of damage data during optimization, a durability analysis is performed after each finite element solver run in the optimization loop. The results of the finite element analysis are directly read in the durability solver and a damage calculation is performed. The results of the damage analysis are provided in a special result block. Then Tosca Structure modifies the components surface based on the damage distribution.

This page discusses:

Preprocessing

The preprocessing of the durability analysis must be performed additionally to the finite element and the optimization preprocessing. All control files must be generated before starting the optimization procedure. A damage calculation run should be performed in advance to check if all required data is available and the durability analysis runs in batch mode without any errors.

Adding Life File to FEM_INPUT

Tosca Structure needs information about the used input file(s) for the life solver. This is added in the FEM_INPUT command:


FEM_INPUT
 ID_NAME   = FILE_INFO
 FILE      = static_analysis.ext
 LIFE_FILE = life_input.ext
END_
Note:

  • The name of LIFE_FILE might have any name.
  • The LIFE_FILE command might be repeated more times for life solvers that support the ONF 601-format (DRESP TYPE = DAMAGE_LC).

For some life solvers, it is often required to add some extra files in the working directory - files that Tosca Structure not always recognizes as default files. The easiest way to copy these files into the optimization working directory is using the COPY_FILE command:


FEM_INPUT
 ID_NAME   = FILE_INFO
 FILE      = static_analysis.ext
 LIFE_FILE = life_input.ext
 COPY_FILE = some_extra_file.ext
 COPY_FILE = some_other_extra_file.ext
END_

In the example above the two files some_extra_file.ext and some_other_extra_file.ext are copied into the working directory at the start of the optimization.

Defining the Objective Function

The design response that is referenced in the OBJ_FUNC command must have the type = DAMAGE. The objective function is formulated as a minimization of the maximum damage.

DRESP
 ID_NAME = dresp_damage
 DEF_TYPE = SYSTEM
 ND_GROUP = design_nodes
 TYPE = DAMAGE
 GROUP_OPER = MAX
 UPDATE = EVER
END_

OBJ_FUNC
 ID_NAME = minimize_damage
 DRESP   = dresp_damage
 TARGET  = MIN
END_

Starting the Optimization in Tosca Structure.gui

  1. Select Start Tosca as Module. The damage solver must be specified.
  2. Select your solver in the LIFE SOLVER list in the additional parameters.



Start of Tosca Structure with a durability analysis (Tosca Structure.gui)

Starting the Optimization on the Command-Line

Specify the damage solver using the ’--life’ flag on the command-line.

Example with Fe-Safe:

tosca hole_damage --solver mscnastran --life fesafe

Postprocessing

After the optimization is finished, all Tosca Structure postprocessing capabilities are available (see Postprocessing of Optimization Results and Result Transfer and Validation Run).

In addition, the damage results might be used for postprocessing. The corresponding result files are stored in the SAVE directories of the optimization system.