Advanced User Settings

With the Advanced User Settings the optimisation parameters can be influenced even further than the options Strut Density and Shape Quality. Furthermore, a few unsupported options are available using the Advanced User Settings like Restart, usage of a Startspace and a minimum Thickness.

The Advanced User Settings can be added to a Scenario by right clicking on this and selecting the option as shown in the picture below.

The appearing text field can be used to add Advanced User Commands to the current Generative Design Scenario.

Restart, Usage of a Start Space & Influencing the Strut Density

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

The software uses six resolution levels from coarse to fine (level 0: 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.

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:

Soft Symmetry

The soft symmetry is activated per default. It influences the design generation so that the part is symmetric in all three dimensions if they were symmetric in the respective dimension to begin with. This is achieved for geometrical symmetrical design spaces even without the hard symmetry constraint.

Equivalence Delta Value:

This governs how far the optimization value of two symmetric elements is allowed to differ while still being considered equivalent. In theory any value works: the higher the value the more zealously the algorithm will try to keep Soft Symmetry, possibly degrading the quality of the produced geometry compared to a non-symmetric one. The default value is 1e-1.

Attempt Soft Symmetry:

Whether or not Soft Symmetry is attempted at all can be (de)activated here.

• off: Soft Symmetry is deactivated.

• always: Soft Symmetry is always on.

• dynamic: The optimisation will start with Soft Symmetry activated but turn it off once no dimension’s symmetry can be salvaged. Note that “dynamic” will never turn it back on once it has turned it off once.

Soft Symmetry Threshold:

Specifies how many asymmetric elements are sufficient for the "dynamic" setting of attemptSoftSymmetry to turn off soft symmetry. Values between 0 and 1 are allowed, where the number represents the proportion of voxels.

The default settings can be changed with the following commands:

Minimum Thickness (Experimental Function):

Minimum thickness of a wall, strut or rib and in general all other resulting shapes. Specified in world units (the default is meters!).

You might also be interested in these tutorials:

• Restart Optimisation