Friction In TimeDependent, Modal Studies

Fatemeh Delzendehrooy

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Hello,

I want to simulate a phononic metamatreial and I want to include the friction in my simualtion. Based on previous discussions I learned that friction cannot be integrated into Frequncy Domain study due to its nonlinear nature which cannot be captured in linear harmonic study. It was suggested to use time dependent. My target is to get tranmission loss vs frequncy. So my question is that can I use time-dependent modal study to integrate the nonlinear nature of friction or I should use general time-dependent study. In latter case, should I get the input/output displacmeemnt at probes for each frequncy to get the transmission loss? Is this simulation reliable?

Cheers


1 Reply Last Post 2024年7月11日 GMT-4 12:12
Henrik Sönnerlind COMSOL Employee

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Posted: 11 minutes ago 2024年7月11日 GMT-4 12:12

You cannot have nonlinearities in a modal study, so you must use a standard Time Dependent study.

This kind of analysis, where you are forced to run periodic problems in time domain is computationally very expensive. For each frequency, you must time-step many periods until you reach a stabilized solution that is independent of the initial conditions.

You can get some improvement by trying approximate the initial conditions using a linear frequnecy domain study.

As an inspiration, take a look at this example:

https://www.comsol.com/model/download/1254561/bracket_general_periodic.pdf
https://www.comsol.com/model/download/1254561/bracket_general_periodic.mph

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Henrik Sönnerlind
COMSOL
You cannot have nonlinearities in a modal study, so you must use a standard Time Dependent study. This kind of analysis, where you are forced to run periodic problems in time domain is computationally very expensive. For each frequency, you must time-step many periods until you reach a stabilized solution that is independent of the initial conditions. You can get some improvement by trying approximate the initial conditions using a linear frequnecy domain study. As an inspiration, take a look at this example:

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