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about deformation in certain time

Posted 27.01.2012, 18:10 GMT-5 Version 3.5a 4 Replies

Hongyi Mi
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Dear All,

Now I am try to simulate a case: a membrane is deformed in certain time eg. 3sec. I don't how to do it in Comsol.
Could you give me any help abou this issue.
Thank you very much.

Best,
Hongyi
4 Replies Last Post 30.01.2012, 15:17 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 27.01.2012, 18:16 GMT-5
Hi

normally it should be straightforward, defne your mode, geoemtry material BC, add a load and run a time / stationary solver. If you have solver convergence issues, check your Initial conditions, and try to use a ramp (heaviside type function) to ramp the load from 0 at t=0

--
Good luck
Ivar
Hi normally it should be straightforward, defne your mode, geoemtry material BC, add a load and run a time / stationary solver. If you have solver convergence issues, check your Initial conditions, and try to use a ramp (heaviside type function) to ramp the load from 0 at t=0 -- Good luck Ivar
Hongyi Mi
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Posted: 1 decade ago 27.01.2012, 22:29 GMT-5
Thank you for your reply.
Actually, I am a little confused.
For example, I want to put a load 100N/m2 on a membrane for 3sec with the edges of membrane fixed.
Could you tell me how set this 3sec?.
Thank you.

Hongyi
Thank you for your reply. Actually, I am a little confused. For example, I want to put a load 100N/m2 on a membrane for 3sec with the edges of membrane fixed. Could you tell me how set this 3sec?. Thank you. Hongyi
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 28.01.2012, 03:40 GMT-5
Hi

I assme then that you want to simulate for lets say 10 seconds and see what happens.

Define a pulse function (rectangle) of 3 seconds duration and a given "smoothing" = ramp time, possibly a start time of smoothing / 2, plot the curve icon in the GUI border to check you start from 0 at t=0 or close to "0", default you satrt at half height that is often rather abrupt),
then select treansient solver, define a time stepping that covers your duration, BUT that has a few points during rampu up and down of your BC pulse
and edit the time stepping sub node (almost at the end of the tree branch) and deselect "free" stepping but use "intermediate or strict" stepping

OK now I notice you are in 3.5, main difference "rectangle" operator do not exist precooked, you nee to call the Heaviside functions and combine two for a step up and down.

But there are many of these discussions on the Forum, sort by version and search for "pulse" or "heaviside"

--
Good luck
Ivar
Hi I assme then that you want to simulate for lets say 10 seconds and see what happens. Define a pulse function (rectangle) of 3 seconds duration and a given "smoothing" = ramp time, possibly a start time of smoothing / 2, plot the curve icon in the GUI border to check you start from 0 at t=0 or close to "0", default you satrt at half height that is often rather abrupt), then select treansient solver, define a time stepping that covers your duration, BUT that has a few points during rampu up and down of your BC pulse and edit the time stepping sub node (almost at the end of the tree branch) and deselect "free" stepping but use "intermediate or strict" stepping OK now I notice you are in 3.5, main difference "rectangle" operator do not exist precooked, you nee to call the Heaviside functions and combine two for a step up and down. But there are many of these discussions on the Forum, sort by version and search for "pulse" or "heaviside" -- Good luck Ivar
Hongyi Mi
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Posted: 1 decade ago 30.01.2012, 15:17 GMT-5
Thank you very much. I will try as you said.

Thanks
Hongyi
Thank you very much. I will try as you said. Thanks Hongyi

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