Metallic strings with carbon fiber

[aerospace2013]

Hello all,

How can I sew carbon fabrics with metallic strings (copper for example) with the diameter of 0.1 mm and 0.25 mm? ordinary industrial machines with needle and bobbin can't do it.... tried it

Appreciate your suggestions

 

[berkshire]

Are you doing this for lightning protection ?
B.E.

You are judged not by what you know, but by what you can do.

 

[aerospace2013]

Mr Berkshire,

Yes.. trying to do so .. do you have any experience in this field.. will appreciate your advice.

 

[berkshire]

I have experience but not in the direction you are trying to go. we used expanded copper mesh not sewn.
B.E.

You are judged not by what you know, but by what you can do.

 

[aerospace2013]

Thank you sir,

Now because you have experience in this field in general (energy dissipation through copper mesh embedded in composites) that is great news for me. How can I contact you with few questions? will email be good?

 

[berkshire]

You can ask on this forum , this will give other experts who also have experience in this field to contribute. I would point out that most of my experience is with Aluminum mesh or foil lightning protection embedded in glass fiber on light aircraft. However this tends not to get used on carbon fiber layups .
B.E.

You are judged not by what you know, but by what you can do.

 

[aerospace2013]

Thank you
Now, regardless the type of fabrics and type of mesh, my major question is the following. once you embed the metallic mesh inside the fabrics and pour the epoxy mixture on them and let them cure, now they are encapsulated inside an insulation material;i.e. epoxy because it is a polymer.
1. How can the whole arrangement (fiber, metallic mesh and epoxy cover) become conductive?
2. how does the energy from the lightening dissipate/flow inside this structure and where does it go

Thank you

 

[berkshire]

Question 1 no. Only the mesh and the carbon fiber layer are conductive, the carbon fiber has a much higher resistance than the metal so the metal is the preferred path.
Question 2 ,You now have a conductive layer embedded just below an insulating layer. Lightning does not care about this tiny layer of insulation and just blows it away.
The result is when you do get a lightning strike, a burn about 1 1/2" is generated on the outer surface exposing the conductive layer, the lightning then travels through the conductive layer to the other side of its path where ever that may be, If you are lucky it will exit through a static discharge wick , if not it will create another burn hole as it leaves. This then creates a repair job for the aviation Technician who patches the foils or mesh then restores the painted surface.
B.E.

You are judged not by what you know, but by what you can do.