What Are the Electromagnetic Parameters of Carbon Fiber for CST Simulations?

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Discussion Overview

The discussion focuses on the electromagnetic parameters of carbon fiber, specifically the permittivity (##\epsilon##), permeability (##\mu##), and conductivity (##\sigma##) for use in electromagnetic simulations with CST. Participants explore the variability of these parameters based on the material's fabrication and application, particularly in the context of simulating radar cross-section (RCS) for drone propellers made of carbon fiber.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant seeks specific electromagnetic parameters for carbon fiber, noting a lack of information in the CST material library.
  • Another participant suggests that carbon fibers are not affected by magnetic fields, proposing that the relative permeability (##\mu_r##) and permittivity (##E_r##) may be close to 1.00, while emphasizing the importance of conductivity (##\sigma##).
  • A participant references a PDF indicating that conductivity (##\sigma##) can vary significantly between 526 S/cm and 2200 S/cm.
  • There is a suggestion that for stealth applications, materials should be chosen to have a surface resistance of 377 ohms, similar to air, and that the design of the propeller and surrounding duct must consider absorptive properties to minimize radar signatures.
  • Participants express the need for more information about the specific application and fabrication methods of the carbon fiber to provide more accurate assistance.

Areas of Agreement / Disagreement

Participants generally agree on the variability of the electromagnetic parameters of carbon fiber and the importance of application context. However, there is no consensus on specific values or methods for determining these parameters, indicating multiple competing views and unresolved questions.

Contextual Notes

The discussion highlights limitations in available data on carbon fiber's electromagnetic properties and the dependence on fabrication methods and application specifics. There are unresolved aspects regarding how to measure or simulate these properties accurately.

Who May Find This Useful

This discussion may be useful for researchers and engineers working on electromagnetic simulations, particularly in aerospace applications involving composite materials like carbon fiber.

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I would like to know parameters of this material, such as: ##\epsilon##, ##\mu## and ##\sigma##, for EM simulations with CST.
I can't find anything similar to carbon fibers or general plastic in the CST material library. Google is not helping me this time.
Does anyone know something more on this topic?

Thanks.
 
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Carbon fibres come in many forms. How is the surface fabricated? What holds it together?

Carbon fibres are long thin resistors. They are not effected by magnets, so ur = 1.00 and I expect Er will also be 1.00 because they are a very small component of the space they fill, but conductivity will be most important. Cross connections between fibres will be determined by the binder that holds them in place. We need more information about your application before we can help further.
Here is a start.
https://pdfs.semanticscholar.org/0f52/20d5451a03a92cad8d9f6ea387a3cc0f0b8a.pdf
 
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From the linked PDF I see that the value of ##\sigma## can oscillate between 526 S/cm and 2200 S/cm.

Baluncore said:
How is the surface fabricated? What holds it together?

Unfortunately, I don't know. I simply would simulate the RCS of a drone propeller, "made of carbon fiber".
 
There are many google hits for; RCS of composite propeller
Maybe search for stealth specifications of composites.

If you want to design a propeller that will not return a significant doppler signature, then you will have to select composites designed to have a surface resistance of 377 ohm, like air. A duct around the prop will also need to be absorptive so the shadow of the prop is not seen. You must select materials based on predictable EM properties.

If you are modeling an existing propeller, you will have to measure it.
Have you been following things like this;
https://www.researchgate.net/profile/Sandor_Bilicz/publication/304371650_The_Radar_Cross_Section_of_small_propellers_on_Unmanned_Aerial_Vehicles/links/5bfe4abb4585157b8172eb44/The-Radar-Cross-Section-of-small-propellers-on-Unmanned-Aerial-Vehicles.pdf?origin=publication_detail
 
Thanks for the documents.
 

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