Menu

Discussion Forum

New Discussion
Filtrer

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.

Hinge model

Posted 8 juil. 2019, 05:30 UTC−4 Structural & Acoustics, General, Structural Mechanics Version 5.4 3 Replies

Sherry
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi all,

I need to model a hinge with structural mechanics module. Is it possible to achieve large rotations? Or it will just work for small rotations? I want to see if its necessary to buy Multibody dynamics module..

Thanks

Shaghayegh

3 Replies Last Post 9 juil. 2019, 11:24 UTC−4
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 5 years ago 8 juil. 2019, 10:56 UTC−4
Updated: 5 years ago 8 juil. 2019, 10:56 UTC−4

Hi,

As long as you can formulate the appropriate set of coupling equations for finite rotations, there is no limitation as such for creating a hinge coupling which works for large rotations. If the axis of the hinge has a fixed orientation, it should not be that difficult. If the hinge axis orientation can rotate, it is a bit trickier, but not impossible.

The only built-in support for various mechanisms is in the Multibody Dynamics module though.

Regards,
Henrik

-------------------
Henrik Sönnerlind
COMSOL
Hi, As long as you can formulate the appropriate set of coupling equations for finite rotations, there is no limitation as such for creating a hinge coupling which works for large rotations. If the axis of the hinge has a fixed orientation, it should not be that difficult. If the hinge axis orientation can rotate, it is a bit trickier, but not impossible. The only built-in support for various mechanisms is in the Multibody Dynamics module though. Regards, Henrik
Sherry
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 5 years ago 9 juil. 2019, 05:09 UTC−4
Updated: 5 years ago 10 juil. 2019, 05:09 UTC−4

Dear Henrik,

Thank you very much for your reply. The hinge which I want to model has a fixed orientation (Y axis). At first I used Form Assembly, then performed following procedures to couple displacements and rotations:

  1. Displacements at Rigid Connector 2 are linked to those of Rigid Connector 1

  2. x- and z- relative rotations are set to be zero, so that only the relative y-rotation is permitted. To express these conditions, I used two Global Constraint(s) nodes.

Rot_x (RC2) = Rot_x (RC1) , and

Rot_z (RC2) = Rot_z (RC1)

Then I apllied boundary load to rotate it. Even with very large forces I only received very small rotations. Can I kindly ask you to check my file as I really need your help.

Best regards,

Shaghayegh

Dear Henrik, Thank you very much for your reply. The hinge which I want to model has a fixed orientation (Y axis). At first I used Form Assembly, then performed following procedures to couple displacements and rotations: 1. Displacements at Rigid Connector 2 are linked to those of Rigid Connector 1 2. x- and z- relative rotations are set to be zero, so that only the relative y-rotation is permitted. To express these conditions, I used two Global Constraint(s) nodes. Rot_x (RC2) = Rot_x (RC1) , and Rot_z (RC2) = Rot_z (RC1) Then I apllied boundary load to rotate it. Even with very large forces I only received very small rotations. Can I kindly ask you to check my file as I really need your help. Best regards, Shaghayegh
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 5 years ago 9 juil. 2019, 11:24 UTC−4
Updated: 5 years ago 9 juil. 2019, 11:23 UTC−4

Dear Shaghayegh,

Even though we sometimes post a quick answer here on the User Forum to questions which have some general interest, I hope that you understand that you cannot expect support from COMSOL staff when it involves debugging specific models. For that you would have to turn to the standard support channels.

The modeling you describe above does however make sense. Since the axis orientation is fixed, it would also be possible to constrain the rotations individually rather than just the relative difference.

Hopefully somone in the user community can help you out here. By the way, if you post a few screenshots, the probablility of getting an answer increases.

Regards,
Henrik

-------------------
Henrik Sönnerlind
COMSOL
Dear Shaghayegh, Even though we sometimes post a quick answer here on the User Forum to questions which have some general interest, I hope that you understand that you cannot expect support from COMSOL staff when it involves debugging specific models. For that you would have to turn to the standard support channels. The modeling you describe above does however make sense. Since the axis orientation is fixed, it would also be possible to constrain the rotations individually rather than just the relative difference. Hopefully somone in the user community can help you out here. By the way, if you post a few screenshots, the probablility of getting an answer increases. Regards, Henrik

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