The rib pattern restriction forces the optimizer to prevent material accumulation and generate
substructures in the form of ribs. The thickness of the individual ribs and the
distances between ribs are averaged over the design area and can be controlled in the
restriction definition. The direction of the ribs is here defined as the out-of-plane
growth direction of the ribs. The rib height depends on the design domain since the full
height in the defined rib direction is used. This should be taken into account when
defining an additional volume/weight constraint.
The following figure shows the quantities that need to be defined for a rib restriction:
