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Best way to model mass-decorated membrane
Posted 10 nov. 2020, 01:38 UTC−5 Structural & Acoustics, Acoustics & Vibrations Version 5.5 1 Reply
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Hi all,
I'd like to model a membrane (strictly speaking a plate, because it has a bending stiffness), decorated with a cylindrical mass in its center, subjected to a sound wave in the frequency domain. So far, my model consists of three cylindrical domains: air before membrane, air after membrane and perfectly matched layer. The interface between the two air domains is the membrane, modeled as shell. The sound wave is represented by an incident pressure field on the inlet boundary of the air before the membrane.
This model solves well and so far I am happy.
However, after I add a cylindrical mass to the center of the membrane, the solver always exits with the error:
" - Feature: Stationary Solver 1 (sol1/s1) Failed to find a solution.
Maximum number of Newton iterations reached.
Returned solution is not converged.
Not all parameter steps returned."
I tried to model the mass as shell (either on top of the membrane shell, or in place of the membrane shell with a circular cutout in the membrane shell, using a rigid connector between the shells). I also tried to model the mass as solid and introduced the corresponding multiphysics interaction between the shell and the solid (solid thin structure connection). I also tried to model the membrane as solid, using either tetrahedral or swept trigonal meshes due to the aspect ratio of the membrane. Always the same error :-(
Does anybody have a good idea how I could resolve that error?
Your help is much appreciated!
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Dear Karsten,
From my initial thoughts, I think you just haven't defined a physics for the mass or applied an appropriate boundary condition, but I am not fully sure without seeing your model.
If your membrane has bending stiffness and isn't truly a membrane, perhaps you can model it in solid mechanics physics along with with your cylindrical mass and define the material properties. I say this as I struggled for some time trying use membrane and solid mechanics physics in the same model. So this may be another suggestion.
You should be able to draw a circle and use an add mass boundary condition as well if that suits your needs.
Hope this helps, Kind regards, TY