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Contact pairs colliding

Posted 18 févr. 2023, 20:39 UTC−5 MEMS & Piezoelectric Devices, Studies & Solvers, Structural Mechanics Version 6.0 1 Reply

John Frerich
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I'm having a problem creating contact pairs for a cantilever simulation. I want the electrode to pull down the cantilever, then the cantilever to make contact with the contact block. I have set up the contact pairs; however, they overlap into one another and do not act as a boundary.

1 Reply Last Post 20 févr. 2023, 11:29 UTC−5
Henrik Sönnerlind COMSOL Employee

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Posted: 2 years ago 20 févr. 2023, 11:29 UTC−5

A quick look reveals some problems in your model (the list may not be exhaustive):

  • In order for the mesh in the air domain not to collapse, you need to set a small offset in the Contact node, for example 0.2[um]. How small you can make that value depends on the quality of the mesh. This effect cannot be ascertained by using the shift in the penalty stiffness curve.
  • You will need to create a user-defined mesh in order to get a fine enough mesh around the collapsing air gap without making the whole model excessively large. Probably a mapped mesh should be used in that region.
  • Avoid using the contact settings for impact analysis in a stationary study.
  • Use an auxiliary sweep in the Stationary node, not an outer parametric sweep. A parametric sweep is used analyze a set of different parameters, while the auxiliary sweep is used to trace a nonlinear solution.
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Henrik Sönnerlind
COMSOL
A quick look reveals some problems in your model (the list may not be exhaustive): * In order for the mesh in the air domain not to collapse, you need to set a small offset in the *Contact* node, for example 0.2\[um\]. How small you can make that value depends on the quality of the mesh. This effect cannot be ascertained by using the shift in the penalty stiffness curve. * You will need to create a user-defined mesh in order to get a fine enough mesh around the collapsing air gap without making the whole model excessively large. Probably a mapped mesh should be used in that region. * Avoid using the contact settings for impact analysis in a stationary study. * Use an auxiliary sweep in the *Stationary* node, not an outer parametric sweep. A parametric sweep is used analyze a set of different parameters, while the auxiliary sweep is used to trace a nonlinear solution.

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