Enforced rotation

[Worldtraveller]

I'm trying to model a frame (see image) with an applied torque, and a set rotational displacement.

The plate is fixed the upper right/lower left corners (UR LL) and the load is applied through a RBE2 at the center of the plate.

It works fine with torque only, but the solver crashes when I try to combine it with enforced rotation. Can the RBE2 not be used in this situation? And what would you recommend for applying this kind of load to simulate an enforced displacement? (The frame has a shaft attached to it that is subject to torque loads, and we want to verify that the frame is ok for some given misalignment (represented by the forced displacement angle).

 

[btrueblood]

Are the imposed rotation and imposed torsion load occurring at the same place, i.e. is the rotation imposed at the RBE2 element?

I can imagine solvers having trouble doing both (i.e. as simultaneous conditions), as the rotation created by the torque load is not the same as the imposed rotation, and the solver has to switch modes.

Why not just find out what the reaction torque is for the imposed rotation, and add that to the imposed torque load in a separate case?

 

[rb1957]

agreed, what is the physical reality of a node having an enforced rotation on top of some elastic rotation from an applied torque ?

if this is what you're trying, run two load cases and combine them

another day in paradise, or is paradise one day closer ?

 

[Worldtraveller]

The physical model is the shaft inputting loads into the frame, but the shaft having some misalignment at the installation. The misalignment is the enforced rotation (checking at some intervals).

 

[rb1957]

then I'd apply the two loads separately and add. the problem the FE is having (as I understand it) is you are telling it that the rotation of a node is a set amount (your enforced rotation) but then you say "oh, btw, there's another load, a torque, applied" which changes the rotation at the point. a pic always helps.

another day in paradise, or is paradise one day closer ?