Menu

Discussion Forum

New Discussion
查找

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Simple structural mechanics model does not converge

Posted 2015年9月3日 GMT-4 10:49 Studies & Solvers, Structural Mechanics Version 5.1 3 Replies

Levin Dieterle
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi,

unfortunately I can't find the reason, why my simple mechanical model does not converge. Can someone help? Thank you.

Kind regards,
Levin

Attachments:

3 Replies Last Post 2015年9月4日 GMT-4 06:57
Edgar J. Kaiser Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年9月3日 GMT-4 12:58
Hi Levin,

I increased the tolerance factor in the 'Fully Coupled' node from 1 to 10 and it solves. This issue may arise from the large aspect ratio of the long thin beam.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi Levin, I increased the tolerance factor in the 'Fully Coupled' node from 1 to 10 and it solves. This issue may arise from the large aspect ratio of the long thin beam. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年9月4日 GMT-4 03:04
Hi,

The model is ill-conditioned because it is undamped and the frequency response sweep passes close to a natural frequency. The solution exactly at a eigenfrequency is infinite, meaning that the dynamic stiffness matrix is singular there.

Edgar's solution makes it possible to solve somewhat closer to the singular point because the ill-conditioning check is modified somewhat, but it does not address the underlying problem.

Regards,
Henrik
Hi, The model is ill-conditioned because it is undamped and the frequency response sweep passes close to a natural frequency. The solution exactly at a eigenfrequency is infinite, meaning that the dynamic stiffness matrix is singular there. Edgar's solution makes it possible to solve somewhat closer to the singular point because the ill-conditioning check is modified somewhat, but it does not address the underlying problem. Regards, Henrik
Edgar J. Kaiser Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年9月4日 GMT-4 06:57
... yes the damping, I miss it at times, something to be looked at first ...

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
... yes the damping, I miss it at times, something to be looked at first ... -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content