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Moving Mesh with Solid Mechanics and Electrostatics
Posted Apr 26, 2015, 11:08 a.m. EDT Low-Frequency Electromagnetics, MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers, Structural Mechanics 4 Replies
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I am trying to model a capacitive force sensor in COMSOL using solid mechanics and electrostatics physics. The model consists of a nylon spring between 2 silicon capacitor plates that experience a boundary load to change the capacitance. I am able to compress the spring and obtain a capacitance reading with a 10V terminal plate and an air dielectric but the capacitance reading does not change with the change in distance between the plates. I have applied a parametric sweep of the boundary load but the capacitance remains unchanged. I attempted to utilize a moving mesh with a prescribed deformation of w in the dz direction but the capacitance still does not change. If anyone has any suggestions on how I can obtain a changing capacitance reading with this current setup that would be helpful.
Thanks,
Josh
Due to a file size error, I have attached an image of the current setup
Edit: I removed the mesh in order to post the model.
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Why did you not use electromechanical physics? It seems electrostatics and mechanics are decoupled. The electromechanical model seems to include both moving mesh and the application of the maxwell stress tensor to calculate bulk and boundary forces. For my system I get a deflection nicely proportional to the square of the applied voltage but only for small deflections and betond that convergence fails, which is frustrating because I am well shy of any sort if pull in condition.
In any case my guess is in your system you are missing the critical physics to calculate force from the electric field and permittivity.
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I actually did try using the electromechanics physics but the basic deformation of my model failed to compute every time for unknown reasons. I know it would probably work better but I figured using the moving mesh would allow me to couple the two physics. Could you possibly show me your setup for the elctromechanics physics?
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Were you able to find a solution.
I have read its related to meshing issues.
I am facing the same problem beyond 50 volts.
Appreciate if you may let me know.
Regards
Rupak