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Coupling Electrostatic and Mechanics
Posted Jun 4, 2014, 5:00 a.m. EDT 1 Reply
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Hi everyone,
I'm working in the deformation of two plates because of a difference of potential. These two plates are in a cube of Air.
I already did the study in 2D and it works. But in 3D is more complicated. Indeed, I created a moving mesh (ALE) as it's recommended in other discussions, but i can't apply the prescribed displacement to all my boundaries. It's written " not applicable".
So i tried to do first the electrostatics in stationnary, then I disabled electrostatics and enabled Structural Mechanics, and do again the stationnary study. But it doesn't work. Furthermore, the surfacique force is given by ((es.nD)^2)/(2*eps_0) but the structural mechanics don't recognise the surface charge density : es.nD and neither its expression : es.unx*(down(es.Dx)-up(es.Dx))+es.uny*(down(es.Dy)-up(es.Dy))+es.unz*(down(es.Dz)-up(es.Dz)).
Please can you help me to couple the electrostatics and structural mechanics.
Thank you,
Steven
P-S : Sorry for my english
I'm working in the deformation of two plates because of a difference of potential. These two plates are in a cube of Air.
I already did the study in 2D and it works. But in 3D is more complicated. Indeed, I created a moving mesh (ALE) as it's recommended in other discussions, but i can't apply the prescribed displacement to all my boundaries. It's written " not applicable".
So i tried to do first the electrostatics in stationnary, then I disabled electrostatics and enabled Structural Mechanics, and do again the stationnary study. But it doesn't work. Furthermore, the surfacique force is given by ((es.nD)^2)/(2*eps_0) but the structural mechanics don't recognise the surface charge density : es.nD and neither its expression : es.unx*(down(es.Dx)-up(es.Dx))+es.uny*(down(es.Dy)-up(es.Dy))+es.unz*(down(es.Dz)-up(es.Dz)).
Please can you help me to couple the electrostatics and structural mechanics.
Thank you,
Steven
P-S : Sorry for my english
1 Reply Last Post Jun 7, 2014, 4:55 p.m. EDT
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Posted:
1 decade ago
Hi Steven,
If you got the electrostatic force to work in 2D it should also work in 3D. It should just require longer solution times and more effort to control the moving mesh. I presented a similar MEMS switch problem also with fluid between the plates in a recent COMSOL Webinar on Fluid Structure Interaction. Check out this link for details www.comsol.com/video/simulating-fluid-structure-interaction-comsol-multiphysics .
If your problem is similar to the one I presented then, unfortunately, you need a 3D analysis to predict the effect of air between the plates (squeeze film damping) since most of the air will escape in the direction perpendicular to the 2D plane that captures the solid deformation.
Nagi Elabbasi
Veryst Engineering
If you got the electrostatic force to work in 2D it should also work in 3D. It should just require longer solution times and more effort to control the moving mesh. I presented a similar MEMS switch problem also with fluid between the plates in a recent COMSOL Webinar on Fluid Structure Interaction. Check out this link for details www.comsol.com/video/simulating-fluid-structure-interaction-comsol-multiphysics .
If your problem is similar to the one I presented then, unfortunately, you need a 3D analysis to predict the effect of air between the plates (squeeze film damping) since most of the air will escape in the direction perpendicular to the 2D plane that captures the solid deformation.
Nagi Elabbasi
Veryst Engineering