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Multiple steps in a simulation

Posted Apr 14, 2011, 6:30 p.m. EDT Studies & Solvers, Structural Mechanics Version 4.1, Version 4.2 6 Replies

Shihai Feng
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Hello COMSOL community,

Is it possible to run a simulation of multiple steps where you have different sets of boundary conditions for each of the steps?

Im hoping to run a 2D structural mechanics contact simulation composed of two steps. The first step involves a block deforming the surface of a larger surface beneath it some amount (deltaY), then I would like to transition to a step where I fix deltaY=0 and create a constant velocity in the x while maintaining the block in a position where the surface underneath it is deformed. The idea is to simulate a block pushing into a larger surface, and then drag it along the surface to study the stresses on the block.

Thanks in advance for your help!

Shihai
6 Replies Last Post Sep 22, 2011, 2:44 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 15, 2011, 1:34 a.m. EDT
Hi

what I do sometimes is to use "Param" as a boolean switch. The only drawback is when the solver has some difficulties, then it tries an intermediate value for the "Param" which does not make any sens

on the BC you then might write something like my_condition = (100 + 200*(Param==1) )*(Param<2)

--
Good luck
Ivar
Hi what I do sometimes is to use "Param" as a boolean switch. The only drawback is when the solver has some difficulties, then it tries an intermediate value for the "Param" which does not make any sens on the BC you then might write something like my_condition = (100 + 200*(Param==1) )*(Param
Mustafa Alam
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Posted: 1 decade ago Sep 20, 2011, 10:31 a.m. EDT
Hi
I am trying similar problem. What I am trying to do a structural mechanics simulation on a capacitive sensor to simulate a vibration and then find the capacitance change with respect to vibration. It means I am doing a vibration simulation and then a electrostatics simulation to find the capacitance change. Is it possible in COMSOL?
Thanks
Hi I am trying similar problem. What I am trying to do a structural mechanics simulation on a capacitive sensor to simulate a vibration and then find the capacitance change with respect to vibration. It means I am doing a vibration simulation and then a electrostatics simulation to find the capacitance change. Is it possible in COMSOL? Thanks
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Sep 20, 2011, 12:17 p.m. EDT
Hi

if you use an eigenmode solver your amplitudes are not "real" so the capacitance value will not be real either.

I would rather deform the structure with a parametric Force or pressure value and with a stationary solver.

By the way I'm replying from a TGV train midway between France and Germany at 317km/h, internet works fine even here, ... today :)

--
Good luck
Ivar
Hi if you use an eigenmode solver your amplitudes are not "real" so the capacitance value will not be real either. I would rather deform the structure with a parametric Force or pressure value and with a stationary solver. By the way I'm replying from a TGV train midway between France and Germany at 317km/h, internet works fine even here, ... today :) -- Good luck Ivar
Mustafa Alam
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Posted: 1 decade ago Sep 21, 2011, 6:50 p.m. EDT
Hi
Thanks for the answer. I am using a time dependent simulation. I have created the vibration with a "prescribed displacement"(at structural mechanics module). But after that I need to find the capacitance simulation. I need to find the capacitance each time.I am attaching a file that will explain what I have done yet.
Hi Thanks for the answer. I am using a time dependent simulation. I have created the vibration with a "prescribed displacement"(at structural mechanics module). But after that I need to find the capacitance simulation. I need to find the capacitance each time.I am attaching a file that will explain what I have done yet.

Attachments:

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Sep 22, 2011, 2:02 a.m. EDT
Hi

Well either you calculate the capacity with the ACDC module physics by using the calculated field, or you calculate / integrate the average distance versus area to get the capacity of a plane paralle plate

Both, in your case, should give similar results (5-10%), at least from my understanding of your model (but I might be wrong as "just" an image is not really enough to understand all the subtilities ;)

--
Good luck
Ivar
Hi Well either you calculate the capacity with the ACDC module physics by using the calculated field, or you calculate / integrate the average distance versus area to get the capacity of a plane paralle plate Both, in your case, should give similar results (5-10%), at least from my understanding of your model (but I might be wrong as "just" an image is not really enough to understand all the subtilities ;) -- Good luck Ivar
Mustafa Alam
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Posted: 1 decade ago Sep 22, 2011, 2:44 a.m. EDT
Thanks for the information. you have written that "Well either you calculate the capacity with the ACDC module physics by using the calculated field"-Thats right I also wanted to do that, but i dont know how I can do that . I have tutorial that computes the static capacitance but not the capacitances which will change with time.I also do not know how I can do multiple step simulation.
Thanks for the answer
Mustafa
Thanks for the information. you have written that "Well either you calculate the capacity with the ACDC module physics by using the calculated field"-Thats right I also wanted to do that, but i dont know how I can do that . I have tutorial that computes the static capacitance but not the capacitances which will change with time.I also do not know how I can do multiple step simulation. Thanks for the answer Mustafa

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