If the drop-down menu Type of forces definition is set to
Force at nodes, Flux writes nodal force values
(vectors) in the exported file that will be imported in
OptiStruct.
On the other hand, if the drop-down menu is set to Global forces
[RBE3], Flux writes a global force for each group of related
elements in the exported file. These global forces are located at the
barycenter of each group. Then, when the exported file is imported in
OptiStruct, the global force vectors will result
equally distributed on each node of the group.
Forces at nodes
In a first hand, the user can usualy exports all the forces at nodes from Flux
project to OptiStruct as shown in Figure 1
Figure 1. Tangential force at nodes at the stator teeth in a permanent magnet
synchronous machine.
As a consequence of this type of export, the produced file contains more datas and
can be more time consuming.
Global forces [RBE3]
In the other hand, an approach for exporting global forces computed in Flux projects
to OptiStruct is also available. This feature is called
Global forces [RBE3] and allows the user to export a global
force. Global forces are located at the barycenter of each group of related
elements.
A typical application of this method is exporting a single equivalent force per tooth
in the stator of a rotating electric machine instead of one force per node. The
situation is depicted in Figure 2:
Figure 2. Global normal forces at the stator teeth in a permanent magnet
synchronous machine.
This approach has the advantage of creating more compact exported data files.
Consequently, subsequent computations in OptiStruct are
faster when compared to the nodal export approach.
This feature allowing the export of global forces is available in the I/O context, as
shown in Figure 3.
Figure 3. Dialog box for creating an OptiStruct export file in Flux 2D, showing the
export option Global forces [RBE3].
