small aircraft bulkhead infusion video

… using core material

http://video.google.com/videosearch?q=carbon+fiber&hl=en&emb=0&aq=f#q=carbon+fiber+aircraft&hl=en&emb=0

Just saw this. The video is a little misleading as it refers to infusing 7 layers, where it’s actually only 4 plies of reinforcement, with 3 layers of core/flow media that provides hardly any structural properties. The flow characteristics of the materials are quite different, so actually infusing 7 plies of reinforcement would be slower and maybe require different setup of lines.

A few notes that may help those watching the video and new to the infusion process or composites in general:

  1. They used peel ply on the bottom of the laminate. Unless one intentionally desires a matte/textured finish on the bottom or the “mold” doesn’t have a proper release agent applied, this is generally to be avoided. Aside from the aforementioned dull finish, it results in a layer of resin being deposited onto the mold surface which can be very difficult to clean off.
  2. The resin feed line setup used in the video will result in a very slow infusion. With any infusion, as the flow front progresses it will naturally slow down just due to friction and permeability of the reinforcements. On the panel in the video this is made much worse by the surface area increasing as the resin moves outward, making the resin feed demand go up while the resin would already have a hard enough time flowing (slows down) even if the surface area stayed consistent. Hope that makes sense! Basically, infuse from the biggest area to the smallest.
  3. The ~4" wide thick material in the middle is a distribution jacket made by Enka. It’s basically a very open and stiff flow media encased in a flat fabric sleeve. Provides very good resin feed and doesn’t leave an imprint like spiral wrap if placed on the laminate.
    Under the feed sleeve, they seem to have placed a small piece of heavy flow media which shouldn’t be necessary. It’s not really helping much unless it covers the whole laminate, but consumes a lot of resin.

Basically using those same materials they could have run the feed sleeve down the middle along the whole length of the panel, inserted the resin feed tube through the side of the bag (less chance of leaks), and put vacuum lines only along the long sides. Faster, easier, and possibly lower material cost.
It’s very noticable too that the panel is still quite flimsy when popped off. Use of a better single core with skins consisting of multiple plies would be stiffer, stronger, and consume less resin.

Tet, what’s the cost of those Enka distribution jackets?

good tip, on starting the resin inlet on the largest side of the part. I have had infusions completely miss areas of parts, happened 3 times on me. Motorcycle fairing laminates were tricky to infuse.