Menu

Discussion Forum

New Discussion
Filter

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 The information provided may be out of date.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.

Inconcistency between 2D axisymmetric and 3D model

Posted Mar 24, 2011, 11:07 a.m. EDT Structural Mechanics Version 4.1 2 Replies

John Smith
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

I have a very simple model : A cantilevered cylinder, radius = 0.4m, length = 10m, fixed contraint at the bottom, free everywhere else.

In 2D axisymmetric geometry this cylinder is modeled by a r=0.4m x z=10m rectangle with it's bottom left edge at (0,0).
The 2D axisymmetric eigenfrequency solver only returns the hight frequency compression modes (see image attached), the lower frequency rocking modes are not computed.
The exact same cylinder computed in 3D returns the wanted lower frequency rocking modes (see image attached)

How to computed those rocking modes in 2D axisymmetric geometry.

Thanks,

John Smith.
2 Replies Last Post Feb 8, 2022, 10:12 a.m. EST
Nagi Elabbasi Facebook Reality Labs
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Mar 24, 2011, 1:49 p.m. EDT
In 2D axisymmetric analysis both the geometry and the deformation must be not vary in the circumferential direction. The displacements of the cylinder’s low frequency bending modes are not axisymmetric so they cannot be picked up in an axisymmetric frequency analysis.

Nagi Elabbasi
Veryst Engineering
In 2D axisymmetric analysis both the geometry and the deformation must be not vary in the circumferential direction. The displacements of the cylinder’s low frequency bending modes are not axisymmetric so they cannot be picked up in an axisymmetric frequency analysis. Nagi Elabbasi Veryst Engineering
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 2 years ago Feb 8, 2022, 10:12 a.m. EST

Starting at version 6.0, the bending eigenmodes of an axisymmetric object can be computed in the 2D axisymmetric interface by selecting the "Circumferential mode extension" option and specifying an azimuthal mode number. Read this blog post for more information on this topic.

Best regards,

Jeff

-------------------
Jeff Hiller
Starting at version 6.0, the bending eigenmodes of an axisymmetric object can be computed in the 2D axisymmetric interface by selecting the "Circumferential mode extension" option and specifying an azimuthal mode number. Read [this blog post](https://www.comsol.com/blogs/axisymmetric-solid-mechanics-with-a-twist/) for more information on this topic. Best regards, Jeff

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