Discussion Forum

Dear COMSOL user community,

Please assist me by answering any or all of the following questions.

I am trying to model an offshoot of the Cantilever beam (as seen in model exchange). The "beam" I am using is a very thin cylinder with the entire perimeter edges (or boundaries) fixed, so that the center area of the thin membrane deflects downward as a voltage is applied to a boundary below.

I'm trying to model this in ver. 3.5a with 2D axial symmetry, hence using the following applications:

Axial Symmetry, Stress-Strain (smaxi)
Moving Mesh (ale)
Electrostatics (es)

Note: I am using Maxwell's stress tensor in the (smaxi) boundary settings because I do not have the MEMS module.

I'm receiving an error upon attempt to solve:
Failed to find a solution for the initial parameter:
No convergence, even when using the minimum damping factor.
Returned solution has not converged.

Q1: Am I using the correct variables for the moving mesh subdomain settings?
dr = R
dz = w

Q2: Are these the correct constraint conditions for the axial symmetry (smaxi) boundary settings for the center (r=0) of the radially-symmetric model?
Boundaries: 1, 5
Constraint Condition: axial symmetry

Q3: Similarly, should I also use axial symmetry for the electrostatics boundary settings on the center (r=0) of the model, at boundaries 1, 3, 5 & 7?

Q4: Finally, are the simple Solver Parameters that I am using (Axial Symmetry analysis = static and Moving Mesh analysis = static) sufficient for this model?

Thanks for your time and help!

Best regards,

Kevin Myhro
Department of Physics and Astronomy
University of California, Riverside
Riverside, CA 92521