About Controls

Shape controls apply additional geometric constraints to the optimization.

This page discusses:

Thickness Control
Manufacturing Controls
Shape Controls

Thickness Control

You can edit the minimum or maximum thickness of selected regions of your model; for example, the minimum thickness of a region in which the optimization creates trusses.

Specifying a maximum size forces the optimization to split thick regions into several smaller regions and prevents it from creating large contiguous regions. Specifying a minimum thickness avoids thin trusses that may be difficult to manufacture.

In most cases you can specify the same value for both minimum and maximum thicknesses, and the optimization creates trusses that are approximately equal to the specified value. To prevent the structure from collapsing, Functional Generative Design tries to avoid creating thin trusses in regions where prescribed conditions are applied.

Specifying the minimum or maximum thickness is very computationally expensive and must be applied with careful consideration. You must perform an optimization without thickness restrictions to identify any regions where the restrictions must be applied.

Manufacturing Controls

The optimization process always creates a structural layout that satisfies the target and the constraints.

Although a design may be possible to create using additive manufacturing, it may be impossible to create using standard manufacturing techniques, such as drawing, casting, or forging. You can apply shape controls that force the topology optimization process to consider only designs that can be manufactured with a standard technique. For example, you can force the optimization to create a castable shape that can be extracted from a mold, or a forgeable shape that can be created with a tool and die.

You can create the following manufacturing constraints:

Casting

Single draw: It lets you create a shape that can be cast where the single mold is removed in a specified pull direction. The central plane, that is the plane at which two halves of a mold meet, lies outside the design space and is perpendicular to the pull direction. The optimization adds or removes material only in the pull direction.
Split draw: It lets you create a shape that can be cast where two halves of a mold are released from the selected central plane in both pull directions. The pull directions are opposite and normal to the central plane. The optimization adds or removes material only in the pull directions.
Auto draw: It lets you automatically compute the positioning of the draw plane along its normal and ensure optimal results.

Milling

It lets you define multiple constraints depending on the selected milling directions.

Extrusion

It lets you create a shape that can be extruded. If the optimization removes an element from the structure, it also removes all the elements behind or in front of the element (relative to the selected pull direction).

Overhang

You can create an ALM overhang control that forces the optimized model to satisfy specified additive manufacturing requirements. The restriction can prevent overhanging features in a model that exceed a critical angle. In general, an overhanging feature with an angle greater than 45º is difficult to print and usually requires the addition of support structures.

Shape Controls

You can create symmetry constraints.

Symmetry

You can create a planar symmetry shape control that forces the optimized model to be symmetric about a selected face, as shown below:

Note: Introducing a symmetry constraint into your model can significantly increase the speed at which Functional Generative Design calculates the optimized structure.

Cyclic Symmetry

You can create a cyclic symmetry shape control that forces the optimized model to replicate a region about a selected axis, as shown below:

You can apply a cyclic symmetry constraint only to the entire design space. Select the axis of rotation and the number of times the region must be replicated around the axis. In the above example, Functional Generative Design has replicated the region twice about the axis at the center of the model.