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Issue: Can not mesh my model

Posted 18.01.2012, 11:50 GMT-5 MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Mesh, Studies & Solvers, Structural Mechanics Version 3.5a 6 Replies

Denis Petrov
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Hello,

I am trying to solve the following problem. My model is an electrostatic actuator. The active element is a prestressed cantilever beam made of two layers of Ni. The layers have different internal stresseswhich makes the beam curl shoul it be released by underetching of the sacrificial layer. The dimentions of the beam are 3000µm*1000µm*20µm. I use symmery, therefore, the width of the model is 500µm instead of 1000 µm. The distance between the beam and the bottom electrode is 0.4 µm. As a basis for this model I am using an example from the COMSOL MEMS Module Model Library "Cantilever Beam" 3D modelling with deformable meshes.

COMSOL successfully returns converted mapped/swept mesh for the beam and bottom electrode. But as soon as I try to mesh the air subdomain (using "mesh remaining(free)") , the following error appears

Error: 4100
Failed to generate mesh for subdomain.
- Subdomain: 2
Failed to respect boundary element edge on geometry face.
- Face: 9
- x coordinate: 0.000227273
- y coordinate: 0.000166667
- z coordinate: 1.04e-005
Internal error in boundary respecting.

I tried to change the aspect ratios for my model. It did not help.
Does anybody know, what could be done to overcome the issue?

Thank you!
6 Replies Last Post 11.03.2013, 15:41 GMT-4
Robert Malkin
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Posted: 1 decade ago 18.01.2012, 12:10 GMT-5
Hi Denis,

I have had a similar error myself a few times and had to subdivide the model into sub sections and mesh them one after the other.

But, I'm sure that you have tried this.

Rob
Hi Denis, I have had a similar error myself a few times and had to subdivide the model into sub sections and mesh them one after the other. But, I'm sure that you have tried this. Rob
Denis Petrov
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Posted: 1 decade ago 18.01.2012, 13:12 GMT-5

Hi Denis,

I have had a similar error myself a few times and had to subdivide the model into sub sections and mesh them one after the other.

But, I'm sure that you have tried this.

Rob


Hi Rob,

thank you!

Well, it seems to be the only possible solution, though my geometries are not that complex (rectangles only).

Regards,
Denis

[QUOTE] Hi Denis, I have had a similar error myself a few times and had to subdivide the model into sub sections and mesh them one after the other. But, I'm sure that you have tried this. Rob [/QUOTE] Hi Rob, thank you! Well, it seems to be the only possible solution, though my geometries are not that complex (rectangles only). Regards, Denis
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 19.01.2012, 00:55 GMT-5
Hi

try to mesh it manually by steps, a few domain by a few domain, start in the middle and go outwards. You may also select different "sizes" per domains to better adapt to the need.

The automatic mesher has difficulties with geometries for example with very different domain sizes, or geometries making loops and that are not very symmetric

--
Good luck
Ivar
Hi try to mesh it manually by steps, a few domain by a few domain, start in the middle and go outwards. You may also select different "sizes" per domains to better adapt to the need. The automatic mesher has difficulties with geometries for example with very different domain sizes, or geometries making loops and that are not very symmetric -- Good luck Ivar
Robert Malkin
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Posted: 1 decade ago 19.01.2012, 05:33 GMT-5
You may also like to try (I am sure however that you have already tried this)...

In the mesh, select

"Custom"

After you have selected your element sizes (min and max), you can set the "Maximum element growth rate" the usual value is 1.5.

(I'm sure you now this, but for others that dont, the "Maximum element growth rate" sets the maximum adjacent element size as a percentage of the smaller element. So if one element is 1m in size, and the growth rate is set to 1.1 the next element will be 1.1m in size)

I have found 1.5 to be much too might for intricate meshes. This does of course increase the mesh size.

Rob
You may also like to try (I am sure however that you have already tried this)... In the mesh, select "Custom" After you have selected your element sizes (min and max), you can set the "Maximum element growth rate" the usual value is 1.5. (I'm sure you now this, but for others that dont, the "Maximum element growth rate" sets the maximum adjacent element size as a percentage of the smaller element. So if one element is 1m in size, and the growth rate is set to 1.1 the next element will be 1.1m in size) I have found 1.5 to be much too might for intricate meshes. This does of course increase the mesh size. Rob
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 19.01.2012, 05:44 GMT-5
Hi

good point, I agree, but I believe you mean "it increases the mesh density" (it decreases the size & increases the number of elements) hence the required RAM size ;)

--
Good luck
Ivar
Hi good point, I agree, but I believe you mean "it increases the mesh density" (it decreases the size & increases the number of elements) hence the required RAM size ;) -- Good luck Ivar
Selcuk Atalay
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Posted: 1 decade ago 11.03.2013, 15:41 GMT-4

Hi

try to mesh it manually by steps, a few domain by a few domain, start in the middle and go outwards. You may also select different "sizes" per domains to better adapt to the need.

The automatic mesher has difficulties with geometries for example with very different domain sizes, or geometries making loops and that are not very symmetric

--
Good luck
Ivar


Hi,

Could you please explain me how to do meshing domain by domain?

I have the similar issue with him.

thanks,

Kimi
[QUOTE] Hi try to mesh it manually by steps, a few domain by a few domain, start in the middle and go outwards. You may also select different "sizes" per domains to better adapt to the need. The automatic mesher has difficulties with geometries for example with very different domain sizes, or geometries making loops and that are not very symmetric -- Good luck Ivar [/QUOTE] Hi, Could you please explain me how to do meshing domain by domain? I have the similar issue with him. thanks, Kimi

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