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Composite Materials Oct 21

What is a composite material?

  • material made of many other materials,
  • the most common and famous one, is wood.
  • different composite structures
    • particles
      • never seen it in rocketry
    • short fibers
      • dump a lot of fiberglass with a resin, and the fibers make the force properties even across the maeterial
    • continuous fibers
      • unisotropic
    • sheet laminates
      • if these are carbon fibers as part of my sheet laminates
      • resin sandwiched between
      • heat will travel along the sheets, so it is unisotropic
  • These properties need to be taken into consideration, its always a good example to see

Structural integrity

  • carbon fiber, is structurally good when layered
  • dont put all the fibers in the same direction, but make them more off axis
  • this makes it more isotropic.
  • This helps reduce

Composite tubes

  • Consider all of the properties of your material
  • for example, carbon fiber is not rf transparent
  • want to make sure that the material is not having consequences to using it

Shaping carbon fiber

  • the carbon fiber is cloths, so you can put it in any shape that you want.
  • fiberglass you cant tell which direction the fiber is in
  • for tubes, they have a process called winding, where they have one long string of material
    • and they roll it around the tube back and forth
  • so if we have a tube made of fiberglass, then the fibers run like this.

Shock cords and bulkheads

  • The shock cord will zipper through the tube
  • destroy the tube, so it wont work well, but you can fix it with epoxy

Glassing

  • Composite materials are essentially sheets of a material, with epoxy infused inside the layers.
  • When we buy the plates for the fins, we dont do that so we just by it.
  • composite materials are very structually sound
  • when we attach the fins, the fillets, here
  • basically we're gonna have layers of composite materials that will be stacked on top of each other around the fins, to make it one piece of composite material
  • basically creating a curved plate of fiberglass.

Glassing Vaccum Baggin

  • so we have a lot of pressure in the air around us, so when glassing, just vaccumbag the fins after glassing to apply a crazy ammount of pressure.
  • you can apply weight,
  • you can put like a vaccum bag
  • the vaccum bag with more layers was significantly thinner
  • the awesome part is that pressure is a scalar field, so the pressure is evenly applied from all sides.
  • do this very careful bagging, to apply an even force around the rocket.
  • hard press all the layers of composite materials.