Tom, Diogo, Ryne and Hallacy

1. List the step-by-step procedures you followed.

1. Cover the worktable with a large polyethylene sheet
2. Cut eight 2" x 12" pieces of uni and eight 2" x 12" pieces of bid
3. Mix one full pump of resin with full one pump of hardener in a disposable bowl
4. Pour some resin along one of your fiberglass strips
5. Cover the strip with resin completely using a spatula
6. Squeegee out as much resin as possible without fraying the fiber
7. Repeat 4-6 for another strip of the same type
8. Lay the new strip on the first one and squeegee out excess resin and air bubbles
For uni/bid strip:
9. Repeat 4-8 until you have a total of 4 strips
For sandwich:
9. Repeat 4-8 but put two strips on one side, two strips on the other, and squeegee out resin and air bubbles
10. Put the completed sample under a wooden board and apply pressure using C-clamps
11. Recover after 24 hours. Use excess resin in the bowl as a control to make sure your sample has cured.

2. Highlight important safety procedures followed while working with composites.
-When working with resin, always wear gloves
-When taking off the gloves fold them over your hand so all the resin is collected inside
-When sanding fiberglass, wear long sleeves and gloves and put on an air mask (fiberglass hurts)
-When finished working with fiberglass, always wash your hands before doing anything else

3. Identify the differences in wetting out uni- and BID fiberglass. Present a hypothesis as to why these differences exist.
There is much more excess resin left when wetting the uni fiberglass in comparison to the bid. The possible reason for this is that squeegeeing the uni is harder that the bid (the uni frays more). Because of the way uni is woven, there are much more gaps that retain resin and it is hard to squeegee it out. You can also only squeegee one direction with the uni which makes it harder to spread out the resin and therefore more is left on.

4. List the physical characteristics of your finished samples.

  • size - length, width, height

Uni- 12" long ,2 1/4" wide
Bid- 12" long ,,1 and 1/2" wide
Uni sandwich and Bid Sandwich-12" long ,2" wide ,and 1/2" high

  • weight - weight before finishing, finished weight, weight of uni plies, weight of bi-plies, weight of foam piece

The Weight of the Uni plies changed from the intila weight of 40 g to the final weight of 34 g
The weight of the bi plies changed from the intial weight of 30 g to the final weight of 28 g
The Uni foam sandwich went from an intial weight of 44g to a final weight of 38 g
The Bi foam sandwich didnt change from its intial weight of 34 g

  • quality of construction - air bubbles?, delamination? voids?

There were some voids and air bubbles in the sandwiches, but it is assumed this is because of the foam. There were no signs of delamination. Overall the contruction is high quality.

  • any other physical characteristics of your sample

The sandwiches are both cconstructed very nicely with the edges being very smooth and straight. The Bid sample is not as good as the edges are slightly curved. The Uni sample is a little better than the bid because the edges are a lot smoother and straighter

5. Judge your fabrication technique by including data on the weight differences of samples. Provide suggestions for improvement of your technique.
It is evident that sample weight (or excess resin) decreased from the first to the last samples. We believe that the technique proposed is fundamentally sound and that the best way to trim down the weight is experience.

6. What impacts would using your original fabrication technique have on an actual airplane? What would a manufacturer do to mitigate these impacts?
The fabrication technique we used is time consuming and is difficult to perfect even with experience (meaning that the airplane is more expensive and heavier). Rather than using a spatula, manufacturers can put the mold with the fiberglass in a plastic vacuum bag and suck out any excess resin. They can apply much, much more force than C clamps to squeeze out resin and also have that resin leak out somewhere rather than staying under the clamp.

7. Were your second day results better than the first day of construction? Why?
Yes, because, as discussed, experience matters.

8. Propose a step-by-step procedure that eliminates (or tries to eliminate) the problems discussed above.
The procedure is fundamentally sound, especially for the classroom. However, if vacuum bags or heavy weights and well-fit molds are available, the samples can reach near-manufactured quality (see Q6).

9. Compare your samples to other group's samples.
(coming soon)

10. Formulate a plan for using both uni- and BID fiberglass on an airplane. Give specific uses for both.
Uni fiberglass can be used on the wings of an airplane so that the fiber goes from the wingtip to the fuselage and resists forces that cause the wing to bend. Bid fiber glass can be used on parts of the airplane that require strength in two directions, such as moving parts like ailerons, flaps, elevators and the rudder. These require strength to resist bending and withstand the forces they apply as control surfaces which extend along the surface.

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