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Structural Mechanics Error When Making Model Smaller

Posted Oct 25, 2023, 9:18 p.m. EDT Geometry, Structural Mechanics, Physics Interfaces Version 6.1 2 Replies

Zafiro Paredes
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Hello,

I am recently starting a project and I wanted to apply the solid mechanic functions with the shell function. I used the block_on_arch file in the COMSOL libraries to understand the functionalities since I am relatively new to structural mechanics.

However, when I attempted to downsize the file from a mm unit to a nm unit, the solver had large errors. I ran the file in mm originally with my desired dimensions and it runs just fine. However, when I change it to nm, it does not produce a result. Is there a measurement in the shell physics, where the error originates from, that I am unaware of? Or is it difficult to apply the same calculations to an extremely small model?

I attached the modified block_on_arch file

Thank you, Zafiro

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2 Replies Last Post Dec 20, 2023, 5:22 p.m. EST
Henrik Sönnerlind COMSOL Employee

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Posted: 1 year ago Oct 26, 2023, 5:26 a.m. EDT

There are a number of issues in your example. This list may not be exhaustive:

  • Essential nodes in Solid Mechanics are disabled, making the model singular
  • The load is 1 exaPa
  • The geometry is not the same as in the original, as different scale factors are applied for different geometrical sizes
  • The variable scalings under Dependent variables assume original units
  • Penalty factor in the Contact node may have to be adjusted

Note that this is a highly nonlinear problem, so you may change its properties fundamentally by changing, for example, aspect ratios.

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Henrik Sönnerlind
COMSOL
There are a number of issues in your example. This list may not be exhaustive: * Essential nodes in Solid Mechanics are disabled, making the model singular * The load is 1 exaPa * The geometry is not the same as in the original, as different scale factors are applied for different geometrical sizes * The variable scalings under Dependent variables assume original units * Penalty factor in the Contact node may have to be adjusted Note that this is a highly nonlinear problem, so you may change its properties fundamentally by changing, for example, aspect ratios.
Zafiro Paredes
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Posted: 11 months ago Dec 20, 2023, 5:22 p.m. EST
Updated: 11 months ago Dec 20, 2023, 5:06 p.m. EST

Hello, I apologize for the late response, I took into account what you said and made some changes and I got some simulations working.

Thank you for your feedback!

Hello, I apologize for the late response, I took into account what you said and made some changes and I got some simulations working. Thank you for your feedback!

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