Influencing the number of iterations, Restart & Usage of a Start Space

Influencing the number of iterations & the Strut Density

To influence the optimisation parameters even further, changes of the number of iterations and number of resolution levels can be made. These settings overwrite the selection of the Strut Density and the Shape Quality as they are only default settings for the ones described here. The table gives an overview of the default settings:

General Optimisation without a manufacturing method:

Optimisation with casting manufacturing method:

The software uses five resolution levels from coarse to fine (level 1: coarse - level 5: fine). The number behind the level indicates the number of iterations calculated on this resolution level. To remove or skip a resolution level the value can be set to 0.

To set up these additional parameters, the Input Commands (left side of the table) need to be added to the optimisation model in the Advanced User Settings text field. In the picture below an example is shown. By adding these Advanced User Settings, the first (coarse) resolution level will be skipped and the optimisation starts directly at the second level. You might want to add more iterations to the remaining levels to give the optimisation the chance to reduce the material accordingly and reach a convergence in each level.

Open

For a general optimisation without a manufacturing method the difference between the Strut Densities is done by an internal geometry smoothing of the elements in the background. Depending on the intensity of the smoothing more, smaller struts (dense) or less, thicker struts (sparse) can be created for the same model & boundary conditions. As long as the later levels (level 4 and level 5) are used these settings also work for different iteration numbers.

For an optimisation with casting as the manufacturing method the difference between the Strut Densities is done by different relative stress target per resolution level.

Restart (Start Space)

With the Advanced User Settings a Restart is possible. A Start Space needs to be chosen with which the optimisation will re/start.

Therefore, an already optimised STL-file is needed as a Start Space. This can be exported directly from the post processing and be selected as a Start Space by clicking on the browse button. Therefore, the unit of the exported STL-file needs to be in meters (SI-Units). In most cases the Strut Density and Shape Quality settings must be changed as well using the Advanced User Settings. For a restart the same resolution level and number of to be completed iterations have to be filled in. You can find a Tutorial to how to perform a Restart here.

This way a two-stage optimisation is also possible. For a two-stage optimisation the resolution level and number of iterations must be chosen wisely and will need some fine tuning.

A Start Space can be marked as a Non-Design Space, thus the Start Space cannot be removed during the optimisation and will be part of the final design. Therefore, the following command need to be added as well: