Discussion Groups

Simulation Mechanical and Multiphysics

Reply
Employee
S.LI
Posts: 398
Registered: ‎05-06-2010

Re: Phantom Displacement Constraints

01-12-2012 05:04 AM in reply to: nosborne

K-nodes are fully constrained.

To check them, select a beam element, right-click and pick up "Beam Orientations", you should see the following picture.

"Use Default" means code generates them at far away places. Otherwise, you should see the coordinates there.

 

 

Untitled.png

----------------------------------------------------------------------------------------------
If this response answers your concern, please mark it as "solved".
Please use plain text.
Employee
sunj.autodesk
Posts: 32
Registered: ‎11-05-2010

Re: Phantom Displacement Constraints

01-12-2012 10:40 AM in reply to: nosborne

Another way to try:

 

Can you temporarily disable/surpress the other parts and only keep the problematic part? Try add some loads and boundary conditions on it and see whether the phantom displacment constraint still exist?

Please use plain text.
Employee
INACTIVE_AstroJohn
Posts: 492
Registered: ‎03-25-2010

Re: Phantom Displacement Constraints

01-12-2012 10:54 AM in reply to: sunj.autodesk

Hi,

 

Actually, I am not sure that you clearly indicated where these "phantom constraints" appear in your model. From looking at your original screenshot, most of us probably assumed the item you were talking about is the circle just underneath the arrow at the top of the image. That's what I assumed.

 

By enlarging the image, I noticed that the circle is orange, not red. Orange circles are beam end releases. I assume that the location coincides with the location where you applied end releases in the FEA Editor. Note that the symbol appears part way between the two nodes on the beam.

 

Sincerely,
John Holtz, P.E.
Senior User Experience Designer, Simulation
Autodesk, Inc.

Current version of Mechanical & Multiphysics: 2013 SP1 (2013.01.00.0012 28-Jun-2012)
Please use plain text.
Active Contributor
nosborne
Posts: 30
Registered: ‎12-19-2011

Re: Phantom Displacement Constraints

01-12-2012 12:06 PM in reply to: INACTIVE_AstroJohn

Sorry to throw you off with the beam end release. I don't know where the phantom constraints are as they do not show up in the model anywhere. I spoke to Pat Tessaro this morning - he has the model and is checking through the database to determine what is really happening. I will be sure and let all know what he finds out. Thanks for all your input.

Please use plain text.
Active Contributor
nosborne
Posts: 30
Registered: ‎12-19-2011

Re: Phantom Displacement Constraints

03-22-2012 05:55 PM in reply to: nosborne

The model had some very poorly shaped elements that were created due to the presence of construction points. The poorly shaped elements resulted in a large variance of stiffness and an ill-conditioned matrix. The only clue was a warning message that the stiffness ratio exceeded a predetermined warning value.

Please use plain text.
Employee
S.LI
Posts: 398
Registered: ‎05-06-2010

Re: Phantom Displacement Constraints

03-23-2012 04:59 AM in reply to: nosborne

Thanks for your update.

----------------------------------------------------------------------------------------------
If this response answers your concern, please mark it as "solved".
Please use plain text.