×
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

WORKBENCH CONVERGENCE PROBLEM

WORKBENCH CONVERGENCE PROBLEM

WORKBENCH CONVERGENCE PROBLEM

(OP)
Hello,

I am trying to simulate angioplasty procedure in a stenosed artery in WB.
I have designed the artery and balloon and imported them in WB.
I have set contact connection as frictionless and penalty method with FKN=0.08.
The project does not converge and the error is
''One or more elements have become highly distorted. Excessive
distortion of elements is usually a symptom indicating the need for
corrective action elsewhere. Try incrementing the load more slowly
(increase the number of substeps or decrease the time step size). You
may need to improve your mesh to obtain elements with better aspect
ratios. Also consider the behavior of materials, contact pairs,
and/or constraint equations. If this message appears in the first
iteration of first substep, be sure to perform element shape checking.''
I have read that the contact interface must have similar mesh but I do not know how to do this...
Also I managed to find the problematic elemnts by using the instructions of
http://www.padtinc.com/blog/post/2012/10/18/Overco... but Ineed help in correcting this problem.
Any suggestions will be accepted!!!thx in advance!!!

RE: WORKBENCH CONVERGENCE PROBLEM

Hello,

I´m not a bio engineer, so I will tell you what I know about the error. The error you are obtaining means there is something you need to improve. Usually this error happens when the local stresses on at least one element make the element distortion very high, and the analysis can´t continue because ANSYS is unable to solve equilibrium equations for that element. Other elements can also be affected as well. This error is most likely due to:
-Mesh: try to obtain meshes with the best aspect ratios possible
- Conditions of the problem: in mechanical, it would be useful to check the loads. Usually passing the loads from concentrated to distributed can fix this error. I don´t know the equivalent to loads in your analysis
-Check constraints. The model can be insuficiently constrained. Constraint the model on areas instead on only keypoints and on regular surfaces. You should, as possible, to constraint the opposite side of the part where you are applying the load. If you are still obtaining this error after all these tries, try to do overlap operations on lines/areas and/or glue on volumes if you have several. If this still does not help, the program simply can´t solve the model with the conditions you impose. Read some papers related about your subject in order to improve the conditions you impose to ANSYS on the simulation.

Sorry for the "mechanical help", but I hope I could help you. Please let me know the outcome.




Regards,
Hugo Silva
Mechanical Eng. PhD student
Materials Eng. MSc.

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