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

Numerical singularity error

Numerical singularity error

Numerical singularity error

I am trying to using the bolt load option in the load module.  It is a simple model with a bolt and nut connecting two plates.  Each plate is being pulled by a concentrate force.  When I run the model the program gives me warning messages that  there are numerical singularities on three nodes each on each plate.  Then it gives an error message saying there are too many attempts.  How do I fix the numerical singularity and what does it mean?  Thanks

RE: Numerical singularity error

Numerical singularity would mean zero stiffness which in turn could be due to insufficient constraining of the material, buckling of a point in your system (geometry -caused such as a weakness pont (imperfection) or it could be due to the high distortion of the material point.

RE: Numerical singularity error

The nodes appear to be around the bolt hole.  Should I add constraints there or would making a finer mesh help?

thanks again

RE: Numerical singularity error

I do not understand exactly what you are doing, but
if you define them as two seperate parts, you need to decide what kind of bonding should exist between them: full bonding (Tie) or with interface properties (allowing sliding at the interface)that you should reasonably estimate based on lab results or judgement say.
However if you define them under one part then the nodes are automatically constrained (full bonding).
Refining the mesh is helpful except in only few cases: for example when high distortion exists and one uses Nonlinear geometry then the small element areas will become zero/negative or close to  which results in stiffness being zero at the associated DOFs
Sometime the huge difference in the stiffnesses of the two adjacent materials will lead to this situation.
Also in order to get more info about the divergence problem you are experiencing you can go to the msg. file in the job directory

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


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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