Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Pro/MECHANICA Thermal Unconstrained DOF

Pro/MECHANICA Thermal Unconstrained DOF

Pro/MECHANICA Thermal Unconstrained DOF

I'm trying to use the thermal portion of Pro/Mechanica for the first time. As a first model to get me going I have mocked up a simple cube with a surface heat load on one side, a fixed temperature on the opposite side, and convection on the other four walls. I keep getting the following error:

"The design study terminated abnormally.

The model is insufficiently constrained for the analysis.
Please review the element connections, properties, and

You may be able to locate your model's problem area by
using Mechanica database ID numbers. ID numbers can be
queried using the "Entity ID" macro in Pro/MECHANICA
Standalone.  The following ID numbers are associated
with this error:


The unconstrained degree of freedom can be seen by running
a constrained Modal Analysis with rigid mode search.
Animating the rigid modes will display the unconstrained
degrees of freedom.  If the error still occurs, then the
issue could be caused by material properties or unattached
spring/mass idealizations."

I do not have any structural boundary conditions in my model – is that my problem? If so, why would you need such constraints for a thermal only analysis (I am not doing coupled thermal/structural)? I am baffled with this – any help is much appreciated.


RE: Pro/MECHANICA Thermal Unconstrained DOF

Update: I have tried adding a structural constraint (I fixed one of the surfaces in all rotations and translations. When I run the Modal Analysis in the Structural portion of Mechanica the model returns no rigid body modes.

I also tried using the Entity ID macro in the Pro/MECHANICA standalone as stated above and the query for the noted ID above simple returns: "The entity with ID 3292 is a Pro Address".

This is very strange ... please help.

RE: Pro/MECHANICA Thermal Unconstrained DOF

What sort of analysis are you running? Stead-state thermal? Transient thermal? Adding structural constraints and performing a modal analysis would be of no help troubleshooting if this is the case...

I just tried an example with your stated thermal loads and BC's, and as expected it worked just fine.

RE: Pro/MECHANICA Thermal Unconstrained DOF

I am running steady state thermal analysis. I agree that structural BC's should not have any impact for pure thermal analysis.

I do not understand what I am doing wrong. I even tried a cube with one surface featuring a fixed temp, the opposite side at a different fixed temp, and all other sides  unconstrained (adiabatic). I still got similar "insufficiently constrained" errors.

I am thinking that I am missing something basic here, as I get the error regardless of what I try to do. Each run I set boundary conditions, select a material, and assign the material to the part. I am not manually meshing the model; instead I am allowing AutoGEM to automatically create my elements during the analysis run. This is driving me crazy.

RE: Pro/MECHANICA Thermal Unconstrained DOF

Hmmmm, perhaps you could post the example prt file here?

RE: Pro/MECHANICA Thermal Unconstrained DOF

Is it possible that your thermal conductivity value has not been set?

Just a thought.

Stephen Seymour, PE
Seymour Engineering & Consulting Group

RE: Pro/MECHANICA Thermal Unconstrained DOF

Well – I knew that it would be something simple! Turns out that I never set a thermal conductivity. The library of materials that we use have assigned structural parameters, but the thermal parameters are not filled in – I never thought to check this!

Thanks a bunch for your help brep and seymours2571!!!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close