Learning Forum

[atb]

I have a simple shaft with two bearings. a gravitational acceleration is the load. A remote displacement is applied at one of the end faces of the shaft to prevent rotation and translation in the x. The other endface is free. I thought this condition was sufficient since the bearings should already constrain the motion in y and z but when I run the solution, I get "Not enough constraints appear to be applied to prevent rigid body motion.  This may lead to solution warnings or errors.  Check results carefully." Any help on this? Please note that I dont want a fixed boundary condition on the end face. Archive file attached. Any help is appreciated. archive file
 

[Erik Kostson]

 

hi

We can not download attachments (Ansys).

 

Please insert some pictures of the mesh and the details of conenctions/contacts and bearings (stiffness in K11, etc).

All the best

Erik

 

[atb]

Hi Erik .here is the extra info you requested. Please note that these bearing stiffness values are arbitrary (1e6 N/mm) but should be large enough. nevertheless, the issue persists.

[Erik Kostson]

 

Hi

I think it is ok and it should run – you aborted it that is why it's red (arrows).

Finally you can also run with weak springs on.

See here how to do that:
https://featips.com/2020/05/14/weak-springs-yes-or-no/

All the best

Erik

 

[atb]

Hi Erik, it does not run, I am sure. I aborted the solution after the error. Not enough constraints. You can also see that I get solver pivot warnings. I'll look into the weak spring thing to see if it helps with my problem

 

 

 

[Erik Kostson]

 

Hi

If you have spring stiffness in the bearings in the Y-Z plane and remote disp. as you have it should be ok.

 

Yes, look into the weak springs (so set them to On), and also turn off pivot check also (Solver pivot checking – under analysis settings)

 

All the best

Erik