Two-Stage-Optimisation - Removing Material/Struts

The Advanced User Settings give the possibility to (re-)start an optimisation with a Start Space. With this option already optimised results can be modified, e.g. struts can be added or removed, and this new geometry can be used as the starting point of the optimisation. With this Two-Stage-Optimisation already optimised geometries can be highly influenced and steered in the desired direction.

In the following the final result of a previous tutorial will be modified and a Two-Stage-Optimisation will be performed. In this case a strut will be removed.

Step 1: Export of the already existing geometry

The first step is to export an already existing geometry. The result from the following optimisation was used in this case:

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The last iteration is selected and exported.

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In general, every previous iteration can serve as a Start Space and can be exported.

Step 2: Reimport of the already optimised geometry

Now the exported geometry is imported into your MSC Apex Generative Design project.
Attention: The Unit system of the exported design from the Post Processing and the chosen unit system for the import must be the same.

The imported geometry is displayed in your model tree as a new part as a faceted solid.

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Step 3: Removal of a strut

With the Sketching and Geometry Tools inside MSC Apex Generative Design a square can be created to remove one strut of the structure. First, a plane is placed where the square is to begin. This plane is created with the Sketching Tool by sketching a rectangle on one of the global planes. The Transform Tool enables the user to place the planes on the desired positions.

Second, the square is created by drawing a rectangle on the plane using the Sketching Tool.The Push/Pull Tool is then used to create the volume of the square. The square doesn’t have to cover the whole strut that is to be removed.

Step 4: Creation of the Start Space

To create the new Start Space the just created strut and the imported optimised shape can be subtracted with a Boolean Operation.

It is not a problem if the square isn’t perfectly removing the full strut. It only has disconnect the strut with enough distance for the algorithm to remove it. The optimisation will redefine the structure accordingly to the Boundary Conditions and Stress Goal.

The resulting faceted solid needs to be exported as an STL-file.
Attention: The unit has to be in meters!

Step 5: Start of the optimisation with the modified Start Space

In the last step the optimisation can be (re-)started with the new, modified Start Space. Therefore, the previous Scenario can be copied.

For the copied Scenario the Advanced User Settings have to be set-up. The path to the modified Start Space has to be selected. Furthermore, the Advanced User Settings are used to adjust the number of iterations for each Resolution Level. In most of the cases a Two-Stage-Optimisation should start directly on the highest Resolution Level or at least on the last two Resolution Levels.

In this case ten iterations on the last Resolution Level are entered. How to adjust the number of iterations for each Resolution Level is explained here.

The optimisation starts with the modified geometry as the first iteration. At the end of the optimisation the strut is integrated completely into the design. Because the new strut is now loaded with stresses other areas of the geometry are less loaded. The optimisation reduces the material accordingly at these areas, thus in most cases the new, modified design is as lightweight as the previous one.

You can check the status of the optimisation in the GD Status and get more information on Warning and Error messages. This can be done directly in the Post-Processing as well as in the Studies tab for an optimisation that has already run.