Composite materials

Composite materials consists of at least two ingredients, of which one is epoxy or polyester, and the other typically is fibre-glass, carbon fibre or teflon.

Epoxy consists of two chemicals, the glue, and the hardener, that must be mixed before it can be used. The duration before it hardens, the work-life, varies, but typically is in the range of 15 mins. It typically takes 24 hours before it is entirely dry though.

Epoxy is very hard when dry. It is very difficult to squash, yet quite easy to snap when bent. Fibre-glass and carbon fibres on the other hand are extremely stong when in traction (pulling), but breaks easily when in torsion (pushing). By combining the epoxy with the fibreglass, we get a material that is strong both in traction and in tortion. The composite material is made by soaking the carbon or glass-fibres in the epoxy, to make a kind of epoxy-fibreglass sheet.

Fibreglass and carbon fibre comes in strands, mats or as woven fabric. Do not buy the mats. They are meant for boat builders. For aircraft use, they do not provide the necessary strength.

Since the fibreglass is bendable before the epoxy is applied, we can make very hard shells in every possible shape and size, by first laying up the fibreglass fabric and then applying the epoxy.

We typically use carbon fibre strands to sandwich between thin wood plates, to give it strength. Woven fibres looks like a piece of cloth and is used to make shells like the airplane cowling, and other parts. Woven fibreglass is also used to make a hard shell on the surface of our models. Typically to give strength, and typically where the original airplane that we are modeling had eluminium plates.

Fibreglass fabric fabric comes in several thicknesses and are ordered in weight per area.

Comments

  • Cathell  says:

    Today, I went to the beach front with my children. I found a sea shell and gave it to my 4 year old daughter and said “You can hear the ocean if you put this to your ear.” She put the shell to her ear and screamed. There was a hermit crab inside and it pinched her ear. She never wants to go back! LoL I know this is entirely off topic but I had to tell someone!

  • computer table  says:

    I think this would be a perfect topic to discuss on Oprah and Naomi Judd’s show.

  • admin  says:

    Sometimes I love bots. I also think Oprah would be the perfect forum for composite materials 😀


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