Hi Greg,
I've also seen a demo of Rigid and Weighted Links - I'd seen them in a
features list, and as I'd hoped they do work similarly to Nastran RBE2
and RBE3 elements, respectively. If you have Nastran-using FEA
colleagues, ask them about these.
I've yet to use them in anger in Pro/M, but basically RLs should work as
rivets or similar fasteners - they constrain two features (surfaces,
edges, points) - or however many they are attached to - to have equal
displacement, i.e. to move rigidly together.
WLs, I believe, force the displacement of the 'central' point to be
equal to the average displacement of the other geometry they're attached
to (or similar maths to this). The main use I have will be to constrain
a shaft as if it is supported in a bearing: by connecting the 'central'
point to a fixed point via a spring, I can allow the bearing journal to
tilt and rotate whilst still transmitting forces - or, I think, to
transmit a torque without being constrained in displacement. Neither of
these is possible with conventional constraints, even with a cylindrical
coordinate system.
You can also use RBE3 elements to act as 'virtual brackets' for loads
applied to a point outside your model geometry; but Pro/M already has
Total Load At Point for this.
Best regards,
Jonathan
