This weeks (optional) assignment is composites. This page covers a project I did with composites, but I figured I would add it for anyone in the class or future classes to look at.
The process was using a vacuum bag to infuse fiber glass and resin to produce a thin but strong 3 ply structural shell.
Unfortunately my documentation of the pre vacuum stages is somewhere in the abyss that was my pre finals hard drive from that semester but the pre- set up but the process was as follows:
-Mill the the shape out of blue foam on the onsrud.
-Set up a clean working space (often over looked but very important.
-Put the basic mold in the vacuum bag to test the suction and seal (this way you don't ruin all of your stuff if you coat everything and stick it in the bag only to find it isn't sealed!!!
-Lay down release film or put mold release on the mold
-Lay down first ply
-Mix Resin A+B
-Coat the first layer
-Apply and coat the second layer
-Apply and coat the third layer.
-Cover with a film that allows excess resin to soak threw into the bleeder, but will still be able to be pulled off after.
-Wrap in seran wrap
-Wrap one more bleeder layer to make sure anything that seeps out doesn't get on the vacuum bag or anywhere else.
-Finally place in the vacuum bag and the result will look something like:
You need to then let it run for about 6 hours (in this case.) Resins have vastly different cure times so you should always check what the set up and requirements for good infusion is on your resin.
After it is finished, you can removed the seran wrap. Here you can see the bleeder layer that soaked up excess resin through the small holes on the release film. Looking at the bottom image, it actually makes a pretty beautiful texture.
The result - A kind of ugly yellowish fiberglass resin composite. However, it was very strong and came out pretty well. We eventually did some load testing that I can upload the results from after finals when I have more time to sort through all of my stuff.