Two-Stage-Optimisation - Adding 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 an additional strut will be added.

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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In general, every previous iteration can serve as a Start Space as well.

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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: Creation of an additional strut

With the Sketching and Geometry Tools inside MSC Apex Generative Design an additional strut can be created. First, two planes are placed where the strut is to begin and end. These planes are 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 beginning and ending of the new strut are created on the datum planes. Therefore, two circles are sketched on these planes. The circles should be created in the same part as the already existing geometry so that the new strut has direct contact to the previous geometry.

The results are two circular surfaces which can be connected to one strut by using the Surface Loft Tool. For this the picking filter on the left side of the tool has to be set to Edges. The result is one strut which is displayed as a solid inside the model tree.

Step 4: Creation of the Start Space

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

It is not a problem if the strut isn’t perfectly integrated into the design. It only has to be in contact with the existing shape. 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 twelve 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.

Step 6: Additional options

When a Start Space is used as in this Tutorial, the Start Space is only the starting point of the optimisation and the shape can be further modified by reducing and adding material.

Another option is to select this new Start Space as a Non-Design Space. This means that the input Start Space cannot be reduced by the optimisation algorithm, only more material can be added to the Start Space.

Attention: Not perfectly integrated struts or other added features will be part of the new design!

The following commands have to be added to the Advanced User Settings:

modified_iteration_64 is the name of the exported and selected Start Space and has to be changed accordingly to the chosen name.