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what is the procedure used in calculating the electrostatic force between two electrodes ?

Posted 10 lug 2011, 19:06 GMT-4 Version 4.0a 3 Replies

Mohamed Aref
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Hi all, i want to understand the procedure used to calculate the electrostatic force between two electrodes when the dielectric between them is air, and the lower one is fixed in all DOFs and the upper one is fixed in Ux & Uy only and Uz is free. and how to use this force as a boundary load to deform the upper electrode in the Uz direction

if i calculate the force by hand and put it as boundary load the deformation is 0.6 um (correct result), if i calculate it from comsol (force name: Fes) and put it in boundary load as force per unit area(es.nTz_Fes ) the deformation is very very small = 6*10^-12 (incorrect result)


i attach the comsol 4.0a file, and i'll wait yours help, thanks

Mohamed.

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3 Replies Last Post 14 lug 2011, 02:53 GMT-4
Edgar Kaiser
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Posted: 1 decade ago 11 lug 2011, 07:41 GMT-4

I am wondering if it is correct to fix the upper membrane in x and y direction?
I am wondering if it is correct to fix the upper membrane in x and y direction?
Mohamed Aref
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Posted: 1 decade ago 11 lug 2011, 07:57 GMT-4

I am wondering if it is correct to fix the upper membrane in x and y direction?


yes to force is in z direction only: normal to the plate plane, so i don't want any displacement in y or x

are you find any error or missing step in my model ?
[QUOTE] I am wondering if it is correct to fix the upper membrane in x and y direction? [/QUOTE] yes to force is in z direction only: normal to the plate plane, so i don't want any displacement in y or x are you find any error or missing step in my model ?
Kun Gao
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Posted: 1 decade ago 14 lug 2011, 02:53 GMT-4
I am just doing this project too. So I may point out some mistakes you did here.

In solid

1. constrain the lower plate wholely but not only the edge.
2. add the bottom face of the upper plate when you set the z-force


In es

1. ground all the lower plate boundaries
2. the same treatment to the upper plate

You may notice the distance between two plates is less than the 0.6um. How do you want it works? So extand the distance between them and then you are all set~
I am just doing this project too. So I may point out some mistakes you did here. In solid 1. constrain the lower plate wholely but not only the edge. 2. add the bottom face of the upper plate when you set the z-force In es 1. ground all the lower plate boundaries 2. the same treatment to the upper plate You may notice the distance between two plates is less than the 0.6um. How do you want it works? So extand the distance between them and then you are all set~

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