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If Statement

Posted 16 avr. 2015, 09:55 UTC−4 Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.4 2 Replies

Cory Stein
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Hello,

I am trying to use an if statement or something similar to apply forces at different times, but I am not sure how to do so. My goal is to compress a figure for a certain amount of time, and then when the time period passes, I want a new force to apply tension and stretch the figure. Is this possible to do within comsol? The figure is currently in structural mechanics and time dependent, but those can be adjusted if needed.

Thanks in advance
2 Replies Last Post 16 avr. 2015, 10:56 UTC−4
Onur Ilkorur
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Posted: 10 years ago 16 avr. 2015, 10:14 UTC−4
Hello Cory,

If I am not mistaken the "If" statement exists under the "Geometry" branch of the model tree. If you are trying to change your geometry with respect to simulation variable "t", then I would suggest you to use a boundary condition like "Prescribed Displacement".

For the boundary condition to change with respect to time, you can use logical operators; like:
-1[mm]*(t<10)+1[mm]*(t>=10)

Please check the syntax as I am typing it from my memory, secondly, please do not use it as an example since the Time Solver will blame itself in the third person, claiming a discontinuity is bothering the solution process. But, the outline of using logical operators under boundary conditions should be evident.

Hope it helps,
Onur
Hello Cory, If I am not mistaken the "If" statement exists under the "Geometry" branch of the model tree. If you are trying to change your geometry with respect to simulation variable "t", then I would suggest you to use a boundary condition like "Prescribed Displacement". For the boundary condition to change with respect to time, you can use logical operators; like: -1[mm]*(t=10) Please check the syntax as I am typing it from my memory, secondly, please do not use it as an example since the Time Solver will blame itself in the third person, claiming a discontinuity is bothering the solution process. But, the outline of using logical operators under boundary conditions should be evident. Hope it helps, Onur
Cory Stein
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Posted: 10 years ago 16 avr. 2015, 10:56 UTC−4
I will try and see if that works.

Thank You
I will try and see if that works. Thank You

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