Menu

Discussion Forum

New Discussion
Filtra

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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.

physical pendulum model

Posted 29 nov 2011, 07:53 GMT-5 Studies & Solvers, Structural Mechanics Version 3.5a 3 Replies

Yadu Krishnan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi all
I was trying to find the motion of a physical pendulum and I checked the sample 2D model ( www.comsol.com/community/exchange/2/ ). It has a Rayleigh damping, but when I remove the damping the solution does not converge but trying with a damping constant very very feeble the solution does converge.
What must be the problem if it is simulated without damping.?
3 Replies Last Post 1 dic 2011, 08:48 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 30 nov 2011, 11:09 GMT-5
Hi

have you tried a eigenfrequency analysis, this gives you the frequencies, even without damping
but an oscillating system without any damping would easily diverge by integrating small numerical round-off errors

--
Good luck
Ivar
Hi have you tried a eigenfrequency analysis, this gives you the frequencies, even without damping but an oscillating system without any damping would easily diverge by integrating small numerical round-off errors -- Good luck Ivar
Yadu Krishnan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 1 dic 2011, 06:53 GMT-5
Hi
Thanks for your reply.
I tried to extrude the 2d geometry and make a 3d pendulum. Included solid stress strain (transient ) and moving mesh (transient). I gave the same initial values of velocity. But when I solve it , the pendulum moves to a particular amplitude and then stops. Even if decrease or increase the time or velocity the pendulum moves the same distance. The solution takes very less time compared to the 2d geometry. How to get a 3d model pendulum.
Hi Thanks for your reply. I tried to extrude the 2d geometry and make a 3d pendulum. Included solid stress strain (transient ) and moving mesh (transient). I gave the same initial values of velocity. But when I solve it , the pendulum moves to a particular amplitude and then stops. Even if decrease or increase the time or velocity the pendulum moves the same distance. The solution takes very less time compared to the 2d geometry. How to get a 3d model pendulum.
Yadu Krishnan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 1 dic 2011, 08:48 GMT-5
Hi
Thanks for your reply.
I tried to extrude the 2d geometry and made a 3d pendulum, included solid stress strain (transient ) and moving mesh (transient). I gave the same initial values of velocity. But, when I solve it , the pendulum moves to a particular amplitude and then stops. Even if we decrease or increase the time or velocity, the pendulum moves the same distance. The solution takes very less time compared to the 2d geometry. How to get a 3d model pendulum ??
Hi Thanks for your reply. I tried to extrude the 2d geometry and made a 3d pendulum, included solid stress strain (transient ) and moving mesh (transient). I gave the same initial values of velocity. But, when I solve it , the pendulum moves to a particular amplitude and then stops. Even if we decrease or increase the time or velocity, the pendulum moves the same distance. The solution takes very less time compared to the 2d geometry. How to get a 3d model pendulum ??

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