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MEMS Stresses and Strains

Posted May 5, 2017, 6:00 a.m. EDT MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Mesh, Structural Mechanics Version 5.2a 4 Replies

Amanda Klaeger
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Hello,

I am relatively new to COMSOL and am trying to model a simple deformation of a MEMS bilayer. My geometry consists of a polyimide support (micro-meter dimensions) and a gold layer on top. I am constraining the polyimide (zero movement in y direction) on one side surface and applying a force on the opposite side surface (in the minus y direction). I am also applying a Roller boundary conditon on the two surfaces which are not orthogonal to the force. Due to the small dimensions of my model, I am obliged to choose a "finer" mesh.

I get the eror "Failed to find a solution. Out of memory during LU factorization. Returned solution is not converged."

I would be greatful for any suggestions that could make my model converge.

Thank you very much,
Amanda
4 Replies Last Post May 12, 2017, 4:04 a.m. EDT
Sergei Yushanov Certified Consultant
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Posted: 8 years ago May 5, 2017, 7:58 a.m. EDT
Amanda,

Try to use Mapped mesh (if geometry is 2D) or Swept mesh (for 3D geometry) to reduce problem size and RAM requirements.

Regards,
Sergei
Amanda, Try to use Mapped mesh (if geometry is 2D) or Swept mesh (for 3D geometry) to reduce problem size and RAM requirements. Regards, Sergei
Amanda Klaeger
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Posted: 8 years ago May 8, 2017, 1:44 p.m. EDT
Dear Sergei,

Many thanks for your answer! I am trying to get a swept mesh to work for my 3D geometry. I'm having difficulties at the interface between the two layers due to the complexity of the geometry. I have managed to get a swept geometry for the resistance part on top. Do you know how I could get the mesh to work at the interface of the two? I'm attaching an image of my geometry.

Thank you very much,
Amanda
Dear Sergei, Many thanks for your answer! I am trying to get a swept mesh to work for my 3D geometry. I'm having difficulties at the interface between the two layers due to the complexity of the geometry. I have managed to get a swept geometry for the resistance part on top. Do you know how I could get the mesh to work at the interface of the two? I'm attaching an image of my geometry. Thank you very much, Amanda

Attachments:

Sergei Yushanov Certified Consultant
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Posted: 8 years ago May 8, 2017, 2:17 p.m. EDT
Amanda,

Attached is thin layer geometry with Swept mesh. You can control layer thickness using global parameter t_layer.

Are you sure that thin layer should be modeled as a solid domain? If the thickness of the layer is small then you can model it as a shell - look at the model example

www.comsol.com/model/heating-circuit-465

Regards,
Sergei
Amanda, Attached is thin layer geometry with Swept mesh. You can control layer thickness using global parameter t_layer. Are you sure that thin layer should be modeled as a solid domain? If the thickness of the layer is small then you can model it as a shell - look at the model example https://www.comsol.com/model/heating-circuit-465 Regards, Sergei
Amanda Klaeger
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Posted: 8 years ago May 12, 2017, 4:04 a.m. EDT
Dear Sergei,

Thank you very much for the file with the example swept mesh, it was extremely helpful! I am now comparing a shell model with a swept model. I think the shell model might be better as you suggested.

Thank you!
Amanda
Dear Sergei, Thank you very much for the file with the example swept mesh, it was extremely helpful! I am now comparing a shell model with a swept model. I think the shell model might be better as you suggested. Thank you! Amanda

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