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.

Thermoelastic (TED) Dissipation in Clamped-Clamped Beam. 2D and 3D don't match.

Posted 11 déc. 2015, 19:04 UTC−5 MEMS & Nanotechnology, Heat Transfer & Phase Change, MEMS & Piezoelectric Devices, Materials, Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics Version 5.0, Version 5.1, Version 5.2 2 Replies

Dustin Gerrard
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello,

I am using COMSOL 5.0 to model Q_TED in a Clamped-Clamped Beam for MEMS applications. I use the same parameters in 2D and 3D model and get different results. I get Q_TED (te.Q_eig) equal to 5.5k in the 2D model and I get Q_TED 8.5k in the 3D case. I have refined the mesh (manually very fine!) and I still get the disagreement between 2D and 3D models.

Furthermore, for a simple beam the Q_TED according to Zener's theory should be around 10k. Why are these models inconsistent and don't agree with the Zener model?

I attached the files.

Thanks in advance.
2 Replies Last Post 14 déc. 2015, 11:21 UTC−5
Dustin Gerrard
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 12 déc. 2015, 00:57 UTC−5
I found this very useful model. When I changed the ends of the beam to "zero temperature deviation" the result matched in the 3D model but the 2D model is still off. What is the issue?

www.comsol.com/model/thermoelastic-damping-in-a-mems-resonator-1439d
I found this very useful model. When I changed the ends of the beam to "zero temperature deviation" the result matched in the 3D model but the 2D model is still off. What is the issue? https://www.comsol.com/model/thermoelastic-damping-in-a-mems-resonator-1439d
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 14 déc. 2015, 11:21 UTC−5
Hi,

In 2D. you must choose whether to use a Plane Stress or a Plane Strain assumption. Neither of them will perfectly match the 3D results due to end effects, but Plane Stress will be closer when the 3D model is free in the third direction.

Regards,
Henrik
Hi, In 2D. you must choose whether to use a Plane Stress or a Plane Strain assumption. Neither of them will perfectly match the 3D results due to end effects, but Plane Stress will be closer when the 3D model is free in the third direction. 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