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 The information provided may be out of date.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.

Initial conditions with strange behaviour?

Posted Jan 5, 2011, 12:44 p.m. EST Modeling Tools & Definitions, Parameters, Variables, & Functions, Results & Visualization, Studies & Solvers, Structural Mechanics Version 4.0a 4 Replies

Christian Engel
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello everybody,

I modeled a 3D-model of two bonded wafers. In a first step they cool down from 400°C and deform due to thermal compression. I want to use the resulting stress as an initial condition for the next step which is also structural mechanics. No further load was applied to the structure so when I plot the Mises-Stress for both steps, I should see the same results. But they differ slightly and I find no explanation for this.

I attached my model, so perhaps somebody could take a look at it?

Thanks a lot in advance
Chris

Attachments:

4 Replies Last Post Jan 7, 2011, 4:00 p.m. EST
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 Jan 6, 2011, 1:18 a.m. EST
Hi

have you done the layered plate exercise in the model library ? the solution is given therein, you need to add a second stationary solver after the first one and then separate the two physics, one per module. And you should consider one plate at the time. See the example

furthermore, you should as your sysadmin or comsol rep to get hands on the latest 4.1 version (and patch it see comsol web site) as there are many limitation or things making life more difficult than needed in v4.0

--
Good luck
Ivar
Hi have you done the layered plate exercise in the model library ? the solution is given therein, you need to add a second stationary solver after the first one and then separate the two physics, one per module. And you should consider one plate at the time. See the example furthermore, you should as your sysadmin or comsol rep to get hands on the latest 4.1 version (and patch it see comsol web site) as there are many limitation or things making life more difficult than needed in v4.0 -- Good luck Ivar
Christian Engel
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jan 6, 2011, 8:17 p.m. EST
Hi,

well, in 2D everything's fine! Separated solvers for both steps were the first thing I tried out... I tried a lot: different boundary-conditions, a finer mesh, but the problem remains.
Don't know what to do now?!

Thought about solving everything in 1 step: cooling down + adding the load. Because it's a stationary solution, that shouldn't be a problem or am I wrong?

Chris
Hi, well, in 2D everything's fine! Separated solvers for both steps were the first thing I tried out... I tried a lot: different boundary-conditions, a finer mesh, but the problem remains. Don't know what to do now?! Thought about solving everything in 1 step: cooling down + adding the load. Because it's a stationary solution, that shouldn't be a problem or am I wrong? Chris
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 Jan 7, 2011, 2:20 a.m. EST
Hi

have you tried to do it in 2 steps, 2 sequential stationary solvers, really the layered plate model methodology works also for 3D

--
Good luck
Ivar
Hi have you tried to do it in 2 steps, 2 sequential stationary solvers, really the layered plate model methodology works also for 3D -- Good luck Ivar
Christian Engel
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jan 7, 2011, 4:00 p.m. EST
Hi Ivar,

what worked now for me: two sequential studies, each with individual solver. The second study assumed the solutions of the first one as initial values. Don't know why ONE sequential solver didn't work?!

However, I've got some new questions regarding boundary conditions. Perhaps it's better to open a new thread...

So far, Chris
Hi Ivar, what worked now for me: two sequential studies, each with individual solver. The second study assumed the solutions of the first one as initial values. Don't know why ONE sequential solver didn't work?! However, I've got some new questions regarding boundary conditions. Perhaps it's better to open a new thread... So far, Chris

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