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Hi,

I want to find out the pull-in voltage of a capacitive cantilever sensor. To do so I did the following:

I chose to do the 2D model first to get an idea, then I added Moving Mesh (ale), solid mechanics, and electrostatics (in order) for my physics and chose a stationary solver.

In geometry I made 3 rectangles (300um * 2 um). I chose the top and bottom rectangles to be gold; the top one is going to be the cantilever and the bottom one is going to be a fixed ground plane.

I chose only the top and bottom rectangles for the solid mechanics module. I chose the middle rectangle, representing the gap to be air. Then is solid mechanics module I fixed the left, right, and the bottom boundaries of the bottom rectangle (the ground plane) and fixed the left boundary of the top one, using the fixed boundary constraint.

I chose air for the electrostatics module. In the electrostatics module, I chose the bottom face of the middle rectangle to be ground and the top face to have a fixed potential.

At the end, I chose the middle rectangle only for the ALE, chose it to have free deformation (free deformation domain), and added a prescribed mesh displacement (after the free deformation) overriding the default mesh displacement. I chose the top and bottom face of the rectangle, and chose u and v for dx and dy.

I used a physics-controlled mesh.

At the beginning when I tried to solve the problem it gave me a Newtonian n iteration number error so I increased the number of iterations; however, the y displacement result that I'm interested in, still does not make physical sense (it is ~3E-308, which is zero).

Would someone be kind to tell me where I am making the mistake? Eventually I am going to need to model the #D version; I tried the 3D version using a similar approach and keep getting 0 displacement as answer. I don't get any errors or warnings from the solver. I have also tried playing with the fixed boundary conditions, and the voltage level to no avail.

Thanks.