Composite Topology and Free-size Optimization

For composite structures, topology and free-size optimization are defined through the DTPL and DSIZE Bulk Data Entries, respectively.

Both are supported in the HyperMesh Optimization panel. Features available include: minimum member size control, symmetry, pattern grouping and pattern repetition.

Topology and free-size methods target a system level composite design where laminate family definition is the objective. Therefore, the PCOMP model should not reflect a detailed stacking of plies of the same orientation. For example, even though 10 layers of 0 degree graphite cloth might be separated in the stacking of the final structure, the modeling for a concept study using topology and free-size should group them together in one ply in the PCOMP, so that the optimal total thickness distribution of a 0 degree ply is optimized throughout the structure.

Involving both topology and free-size in the same optimization problem is not recommended, since the penalization on topology components creates a bias that could lead to sub-optimal solutions.

Note: Prior to OptiStruct 8.0, composite topology optimization was based on the notion that the homogenized properties of an element remain unchanged. This construct does not allow the freedom for material redefinition. However, if this is indeed a preferred assumption, the HOMO option can be set on the MAT line of the DTPL card. Otherwise, an individual ply-based formulation (discussed above) will be the default option.