---------------
When creating an RFORCE boundary condition in NX, I select a pre-existing node
as the reference point, but when using Solver Syntax Preview, the RFORCE card
does not utilize the pre-existing node, why?
Solution
The RFORCE Boundary Condition's definition defines the axis of rotation.
Since you cannot pick a node (label or filter by node) in the menu for the
RFORCE in NX, then NX cannot export the RFORCE card using that grid ID. When
NX translates the RFORCE card into the NX Nastran deck, it creates a new
orphan node at the selected location which is fixed in all DOF and is
referenced by the RFORCE card.
Also, the rotation force is being applied to the entire model, not at the
rotational axis point. So when the formatter uses the new orphan node at the
exact same location as the axis point node, the physics of the model are the
same. The BC's definition does not allow the user to use a predefined node
(defined in the FEM) in the definition of the axis of rotation.
Notes