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Importing STL Files with features that vary drastically in size

Posted Mar 22, 2022, 1:26 p.m. EDT Structural & Acoustics, Interfacing, CAD Import & LiveLink™ Products for CAD Version 5.5 4 Replies

Gabriel Portillo Pauna
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Hi all,

I attached the STL file that I'm trying to import into COMSOL. The STL file contains 100 grains( ~100 um in size), that are separated by a thin grain boundary (1 nm). This creates a difference in size of about 100,000: 1 size ratio. The STL file can be visualized correctly in Solidoworks, but when opening it in COMSOL, the grains begin to overlap (screenshot attached).

Two Questions: 1) Am I doing the import incorrectly? 2) Is this not possible with just Multiphysics COMSOL and do I need to get the CAD Import Module? 3) Would the CAD Import Module even be able to handle the 100,000 : 1 ratio size difference?

Greatly appreciate any feedback!

4 Replies Last Post Mar 22, 2022, 5:51 p.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago Mar 22, 2022, 1:54 p.m. EDT

Gabriel,

I often found STL imports difficult. It might work better by importing the native Solid Works format, but you need the CAD import module for that. But the main issue is probably this huge ratio in dimensions. And geometry import is only one step. Even if you manage that, you will fail with meshing it. You don't tell what this tiny gap is needed for. In general you would try to avoid the gap and handle the function it has by an appropriate boundary condition.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Gabriel, I often found STL imports difficult. It might work better by importing the native Solid Works format, but you need the CAD import module for that. But the main issue is probably this huge ratio in dimensions. And geometry import is only one step. Even if you manage that, you will fail with meshing it. You don't tell what this tiny gap is needed for. In general you would try to avoid the gap and handle the function it has by an appropriate boundary condition. Cheers Edgar
Gabriel Portillo Pauna
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Posted: 3 years ago Mar 22, 2022, 2:14 p.m. EDT

Hi Edgar,

Thank you for your response.

The intent of the gap is to simulate the grain boundary that exists between the grains. The goal is to simulate joule heating and analyze how much voltage is needed to impact only those thin boundaries and not impact the grains themselves (they will have different material properties).

This was performed in COMSOL with 2-D setup and my task is to explore if possible in 3D.

Thank you, Gabe

Hi Edgar, Thank you for your response. The intent of the gap is to simulate the grain boundary that exists between the grains. The goal is to simulate joule heating and analyze how much voltage is needed to impact only those thin boundaries and not impact the grains themselves (they will have different material properties). This was performed in COMSOL with 2-D setup and my task is to explore if possible in 3D. Thank you, Gabe
Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago Mar 22, 2022, 2:42 p.m. EDT

I see, in this case you might use a 'Contact Impedance' BC on the boundaries beween the grains in AC/DC and a 'Thin Layer' in Heat Transfer. In this approach you must not have any gap between the grains.

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
I see, in this case you might use a 'Contact Impedance' BC on the boundaries beween the grains in AC/DC and a 'Thin Layer' in Heat Transfer. In this approach you must not have any gap between the grains.
Gabriel Portillo Pauna
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Posted: 3 years ago Mar 22, 2022, 5:51 p.m. EDT

Awesome, thank you! Will try that!

Awesome, thank you! Will try that!

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