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Defining contact for a large number of surfaces

Posted Sep 5, 2024, 12:56 p.m. EDT Structural & Acoustics, Structural Mechanics, Structural Dynamics 3 Replies

FDZR
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Hello COMSOL users,

I have numerous surfaces that I want to define contact for. I know I can use contact pair but its not possible for me because each surface can be in contact with multiple surfaces or even itself during loading. Is there anyway that we can define a general contact for any surfaces touching another or itself?

3 Replies Last Post Sep 10, 2024, 10:49 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 7 months ago Sep 6, 2024, 3:02 a.m. EDT

In principle, you can just select all the boundaries both as source and destination in the contact pair. Please read what is said about self-contact in the documentation, since there are some caveats.

The time for contact search may however become long if there are many boundaries involved. Depending on the general model size, you may have to equip yourself with a bit of patience.

Setting the search distance in the contact pair to a reasonable value will help you in this situation.

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Henrik Sönnerlind
COMSOL
In principle, you can just select all the boundaries both as source and destination in the contact pair. Please read what is said about self-contact in the documentation, since there are some caveats. The time for contact search may however become long if there are many boundaries involved. Depending on the general model size, you may have to equip yourself with a bit of patience. Setting the search distance in the contact pair to a reasonable value will help you in this situation.
FDZR
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Posted: 7 months ago Sep 8, 2024, 5:09 p.m. EDT

Thank you very much

I use this method and I found loaded-spring-contact.mph (https://www.comsol.com/model/self-contact-of-a-loaded-spring-109781) for this simulation. However, currently I have issue with running. I'm running my contact simulation using time dependent study for two days and it has 4% convergence until I stopped that. For this case I'm using generalized alpha method with 0.75 alpha and I defined Nitsche contact. Mesh is refined and I'm using ramp load on my harmonic displacement. Without any contact the simulation runs for fair amount of time. I also used Penalty contact but got this error: - Feature: Time-Dependent Solver 1 (sol1/t1) Nonlinear solver did not converge. Time: 5.4253472222222225e-09 s. No convergence, even when using the minimum damping factor. Last time step is not converged. I noticed that even with increasing the number of iterations I cannot help with convergence. Once I apply the contact it cannot converge. Do you have suggestion how can I improve convergence in contact problem?

Thank you very much I use this method and I found loaded-spring-contact.mph (https://www.comsol.com/model/self-contact-of-a-loaded-spring-109781) for this simulation. However, currently I have issue with running. I'm running my contact simulation using time dependent study for two days and it has 4% convergence until I stopped that. For this case I'm using generalized alpha method with 0.75 alpha and I defined Nitsche contact. Mesh is refined and I'm using ramp load on my harmonic displacement. Without any contact the simulation runs for fair amount of time. I also used Penalty contact but got this error: - Feature: Time-Dependent Solver 1 (sol1/t1) Nonlinear solver did not converge. Time: 5.4253472222222225e-09 s. No convergence, even when using the minimum damping factor. Last time step is not converged. I noticed that even with increasing the number of iterations I cannot help with convergence. Once I apply the contact it cannot converge. Do you have suggestion how can I improve convergence in contact problem?
Henrik Sönnerlind COMSOL Employee

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Posted: 7 months ago Sep 10, 2024, 10:49 a.m. EDT

It is almost impossible to guess. This is a situation where you should contact support, if you have such a possibility.

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Henrik Sönnerlind
COMSOL
It is almost impossible to guess. This is a situation where you should contact support, if you have such a possibility.

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