×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

BackUpRoll Contact problem ***WARNING: SOLVER PROBLEM. NUMERICAL SING

BackUpRoll Contact problem ***WARNING: SOLVER PROBLEM. NUMERICAL SING

BackUpRoll Contact problem ***WARNING: SOLVER PROBLEM. NUMERICAL SING

(OP)
Hi
i'm trying to simulate the behaviour of a backuproll under radial load, to undestand the forces distribution on the roller (taking into account outer ring deflections and deformation).

I got error like:

 ***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE RULLO-1-RAD-4.36 D.O.F. 2 RATIO = 5.89045E+13.

They was along 1 2 or 3 dof, so i provided to create bc for every roller, so that the roller can move only in the direction (inner ring point contact) to (outer ring point contact).

After the change, i got always a lot of singularity, but only in the direction 1:

 ***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE RULLO-1-RAD-4.36 D.O.F. 1 RATIO = 5.89045E+13.

I can't undestand how can i write better boundary condition. It looks like there's some rigid motion, and it could be, because outer ring is deformable.

What could i do to gave abaqus a way to avoid this singularity?

Fabio

 

RE: BackUpRoll Contact problem ***WARNING: SOLVER PROBLEM. NUMERICAL SING

It's probably due to the contact. You need to define a step in which every part is restrained or has imposed displacements so that contact forces are initialised between the parts. Only then in the 2nd step can you release some of those imposed displacements to allow the true loads.  

Tata  

RE: BackUpRoll Contact problem ***WARNING: SOLVER PROBLEM. NUMERICAL SING

(OP)
Corus thanks for the reply!

Do u mean that i've to "use more boundary condition" in the new first step? For example, everything except the outer ring is blocked?

Thx again!  

RE: BackUpRoll Contact problem ***WARNING: SOLVER PROBLEM. NUMERICAL SING

Blocked would be the wrong word. Think of it as pushing everything together so that all the parts make contact with each other. For 'push' use a displacement value. You'll obviously have to impose other 'fixed' zero restraints so that you have something to push against.  

Tata  

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!


Resources