Model Preparation Comments for Multiple FEM Configuration

 

If multiple FEM configurations will be processed in the GA then the above model preparation steps should be performed on each FEM configuration independently. All common regions of the multiple FEMs must have the same node numbering. For example, if the two FEM configurations that will be run simultaneously in the GA are an aircraft with under-wing fuel tanks and the same aircraft with wing-tip fuel tanks, then the main structure of the aircraft must be modeled with the same FEM and node numbering for both configurations. Similarly, the under-wing fuel tank and the wing-tip fuel tank portions of the FEMs cannot have any overlap in DOF numbering. This is because the GA assumes that any DOF that is common to all FEM configurations represents the same physical location on each structure.

With multiple FEM configurations it is suggested that the candidate set for each FEM configuration be determined individually then combined to create a single candidate set that is the union of the individual candidate sets. The candidate set of DOF used during the EXTOUT, DMIGPCH operation for each FEM configuration should be the intersection of each FEM’s total DOF with the overall candidate set. This ensures that the GA is aware of all DOF in the candidate set that are common to all FEMs.