Goal

design and make a 3D mold (~ft2), and produce a fiber composite part in it

Video

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Challenges

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Related Classes

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Class Notes

Picking up from molding/casting
Making parts that are: larger, lighter, stronger

Composites are a division of labor and materials
compression vs tension
in each case there is a fiber and a matrix
One of the most important is concrete and rebar
Concrete is great for compression, but will crack right away
rebar handles tension loads on a structure
Wood is a natural composite of fiber and resin

Fiber – long fibers are good to carry force throughout structure
natural fibers – not as strong as carbon, but environmentally friendly
burlap – not too coarse or too fine

resin – most common choice is epoxy
needs to be low enough viscosity that it permeates fiber matrix.
hydrostone can be used as a resin.
natural resins – not ready for use.

Lyocell – patented fiber. can absorb 10x more water than cotton.

Boat building suppliers are very good vendors for composite materials.

To make a composite:
1. A single layer of fiber is not a composite. You need multiple plies.
2. Radius of curviture – outside plies go longer than inside plies.
3. Core is a very light material. Outside layers do most of the work.

James Clerk Maxwell – “On reciprocal figures, frames and diagrams of forces”

Rule of thumb: you want equal amounts of fiber and matrix equally spaced.

Open mold – lay up plies of fiber on surface of positive image.
closed mold – clamp plies between positive and negative images in tooling.

Wet layup – glob on resin on top of plies
pre-pref – heat fiber that comes with a matrix that must be stored cold.

pultrusion is like extrusion, but you are pulling.

need to define 3D tooling.

Safety:
Breathing stiff fibers is a health issue. Fiber glass cannot be metabolized and will stay in lungs.

Priority is light/strong parts. Tool is optionally the core of the project.

Review Materials

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Assignment

Proposed assignment: construct a Mardi Gras prop in the style of Blaine Kern

Of all of his accomplishments, Kern said Thursday that the greatest thing he did to grow his business empire was convincing krewe leaders to admit minority groups and eventually women members.

“In the 1950s, Mardi Gras was a very closed off, very elite thing,” Kern said. “I opened up Mardi Gras for everybody, and by doing that it was able to blossom into what it has become today. Fortunately, Darwin was very open minded for the time.”
http://www.dailycomet.com/article/20140220/ARTICLES/140229940