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Creating a shaped membrane for a resonator eigenfrequency study

Posted Feb 28, 2024, 9:47 p.m. EST Acoustics & Vibrations, Geometry Version 6.1 3 Replies

Benedikt Gregor
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Hello everyone, I am running into an error when defining a more complex shape for my membrane.

The goal is to emulate a graphene resonator and analyze how the shape of the membrane influences the quality factor using an eigenfrequency analysis.

Whenever I try to add more than one primitve to my geometry to make "holes" in the membrane I run into this error:

2024-02-28T20:38:12.504-0500 ERROR com.comsol.model.data.SelectionOutOfBoundsException: Illegal_input_vector_illegal_entity_number [com.comsol.widgets] com.comsol.util.exceptions.BridgeRuntimeException: com.comsol.model.data.SelectionOutOfBoundsException: Illegal_input_vector_illegal_entity_number

I am still fairly new to using COMSOL and suspect I am defining something incorrectly. The COMSOL file has a Membrane, Solid Mechanics and Multiphysics Solid-Thin Structure Connection Interface.

The error can easily be reproduced by enabling another primitve under "Plane Geometry" and running the "initial stress/strain" Eigenfrequency study.

I've attached one screenshot showing the deformation of the membrane with one primitive circle cut out. The second screenshot shows the error I get when I add another one.

If someone also has some suggestions on how to implement a topology optimization for the membrane to achieve a high Q to this I'd be very grateful.

Thank you for any help on this.

Regards, Benedikt

3 Replies Last Post Feb 29, 2024, 4:46 p.m. EST
Acculution ApS Certified Consultant
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Posted: 8 months ago Feb 29, 2024, 2:33 a.m. EST

I could not see any issues. Attached is a picture where the interpolation curves have been added (the import does not work without the dxf file).

-------------------
René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
I could not see any issues. Attached is a picture where the interpolation curves have been added (the import does not work without the dxf file).

Attachments:

Benedikt Gregor
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Posted: 8 months ago Feb 29, 2024, 9:57 a.m. EST
Updated: 8 months ago Feb 29, 2024, 9:55 a.m. EST

Hi Dr. Christensen, Thank you for testing the file.

This is a very interesting result. I couldn't get this work ever.

I was so baffled by this that I just now downloaded the file I uploaded to this discussion and it really does work! This must have something to do with the fact that I cleared all solutions to reduce file size for the forum upload.

I just now tested this idea by running the study twice. The second time fails! After clearing all solutions from the Study menu it works again.

The software must be doing something I don't yet know about with previous solutions.

I learned something today. Thanks!

Would you have any suggestions about how to go about doing a topology optimization using the Membrane Interface?

Regards, Benedikt

Hi Dr. Christensen, Thank you for testing the file. This is a very interesting result. I couldn't get this work ever. I was so baffled by this that I just now downloaded the file I uploaded to this discussion and it really does work! This must have something to do with the fact that I cleared all solutions to reduce file size for the forum upload. I just now tested this idea by running the study twice. The second time fails! After clearing all solutions from the Study menu it works again. The software must be doing something I don't yet know about with previous solutions. I learned something today. Thanks! Would you have any suggestions about how to go about doing a topology optimization using the Membrane Interface? Regards, Benedikt
Acculution ApS Certified Consultant
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Posted: 8 months ago Feb 29, 2024, 4:46 p.m. EST

I can still not recreate the problem, even running it several times. Strange. You should submit a support case.

You can set the optimization up to control Young's modulus and density for the eigenmode study. You could, however, also consider controlling the thickness parameter instead, perhaps there is something to be had with that approach.

-------------------
René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
I can still not recreate the problem, even running it several times. Strange. You should submit a support case. You can set the optimization up to control Young's modulus and density for the eigenmode study. You could, however, also consider controlling the thickness parameter instead, perhaps there is something to be had with that approach.

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