Change in Capacitance after applying a force to the device
I've been working on a relatively straightforward capacitor structure that I'm trying to simulate. I have a top electrode sitting centrally over four bottom electrodes (four differential capacitors). The dielectric material is a flexible poymer (Ecoflex-30) that is patterned into posts.
I'm interested in modelling the response of this structure under forces in different directions (normal force, in plane force, force at an angle). I'm currently modelling the device in Maxwell to get an idea of the initial capacitance, sending it to a static structural module to compute the displacement of the structure under the force and exporting the results back to Maxwell using a feedback iterator loop.
I'm having issues trying to understand my results. For example, when I apply a normal force, I am expecting the values of all the 4 capacitances to increase, until it saturates. However what I observe is a decrease in the capacitance with some random spikes and I haven't been able to understand where this is coming from.
My guess is that it might have to do my mesh, but I do not know how to verify this and figure out whether I should change things up on the maxwell side or the static structural end. What I do observe is that based on my meshing geometry choices the way the imported load (body force density) from Maxwell is mapped changes significantly.
I'm hoping that I can get some tips on how to analyze this and perhaps on how I can improve my meshing.
Below is a picture of the imported load from Maxwell plotted as a body force density . Here the dielectric layer has been meshed with a different body size.
Below is a picture of the imported load from Maxwell plotted as a body force density . Here the dielectric layer and the top and bottom electrodes together have been meshed with a different body size.
I'm using Ansys 17.2 and have uploaded the workbench file for reference.