Divergence on piezoelectric domain

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Hello to all,

I'm trying to create a 2D model of an ultrasonic NDT using Elastic Waves, Time Explicit with Electrostatics. I used the tutorial "Angle Beam Nondestructive Test" (https://www.comsol.com/model/angle-beam-nondestructive-testing-78811) as starting point for my own model, but I'm having some trouble with the Piezoelectric domain.

I assigned an edge as Electric Potential boundary condition and to create a pulse I inserted an Analytic function as voltage input, just like the tutorial. The simulation starts fine, but after a while, the electric potential in the piezoelectric domain grows and I can't figure it out why. I attached a plot of the average electric potential on the edge, in this image is visible the input pulse and how exponentially the voltage grows after some point.

I thought that it could be a mesh problem, so I tried to refine it, but that didn't work. Anyone faced a similar problem?

Thank you in advance,

Rodrigo Pires



3 Replies Last Post 21 mag 2024, 09:20 GMT-4
Mark Cops COMSOL Employee

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Posted: 4 weeks ago 17 mag 2024, 15:22 GMT-4

The graph is indicating that the solution is diverging. Since there can be various reasons for this, you would need to submit your .mph model file in order to get some specific suggestions for your model.

-Mark

The graph is indicating that the solution is diverging. Since there can be various reasons for this, you would need to submit your .mph model file in order to get some specific suggestions for your model. -Mark

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Posted: 4 weeks ago 21 mag 2024, 08:58 GMT-4

Hello Mark, thanks for your reply!

I’m attaching the .mph file to this topic. I’m sorry, but I had to exclude the mesh and result to get the right file size for uploading.

Thanks in advance, Rodrigo

Hello Mark, thanks for your reply! I’m attaching the .mph file to this topic. I’m sorry, but I had to exclude the mesh and result to get the right file size for uploading. Thanks in advance, Rodrigo


Mark Cops COMSOL Employee

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Posted: 4 weeks ago 21 mag 2024, 09:20 GMT-4
Updated: 4 weeks ago 21 mag 2024, 09:29 GMT-4

It looks like there is no damping in any of the solids, even the "Damping material". It could help to add some Rayleigh damping - similar to what was done in the angle_beam_ndt model. Secondly, both piezo domains currently have the same coordinate system used for the poling direction. Is this correct? It would seem that due to the different angle, each piezo would need a separate base vector system to define its poling direction relative to the mount angle.

It looks like there is no damping in any of the solids, even the "Damping material". It could help to add some Rayleigh damping - similar to what was done in the angle_beam_ndt model. Secondly, both piezo domains currently have the same coordinate system used for the poling direction. Is this correct? It would seem that due to the different angle, each piezo would need a separate base vector system to define its poling direction relative to the mount angle.

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