Composites

Ok pals?..here we are again onto another fun week of composites which quickly springs my mind back to the Molding and Casting week which saying fun isn't fun...the requirement was quite straight forward in terms of practice and implementation: It was to practically design and make a 3D mold (~ft2), and produce a fiber composite part in it...First the materials we dwelt upon was very diverse according to my prior interaction with composite materials at school...various ways were provided in conjuction with the material:
Compression and Tension modes of creation catered for epoxy+carbon fiber, concrete+rebar, fiberglass,FR1,FR4, TIRE, WOOD,,also Fiber included chopped substances, filament, tape and fabric, glass, carbon, aramid, kevlar and natural materials such as cotton, silk, bamboo, wood, linen and burlap...also matrix as material mode included epoxy, polyester, phenolic, urethane, wax, cement and several natural such as plant resins and sugars...
Design featured components such as plies, radius of curvature and cores..
Importantly was the processes involved in composite creation and several ways were given citing: Compaction, Infusion, volume fraction, open mold, closed mold, wet lay-up, pre-preg, RTM, VARTM, Compression molding and Vacuum bagging(mold,release,laminate,core,peel,ply,bleeder,breather,bag, sealant tape,pump),,also autoclave,pultrusion and clear coating.
We shouldn't forget the molds themselves and how they come to be: MOlds are and can be produced in many ways but the locally available means in the lab included Machined molds using Computer controlled cutting such as SHOPBOT or Modella,,also molds can be folded after placement of material such as gypsum or hydrostone in a fabric etc,,and lastly in th elab the composite can be skinned so as to come up with sort of a replica.
Every nice thing has got safety measures and regulations and not excluding Composites creation..several safety guidelines were handed in the lecture verbally but brief pointings included being aware of harmful particles, inhalation, rashes incase of contact with the comprising processing materials..
Respirators, Goggles, gloves, fumes, ventilation and netshape options were all guaranteed to atleast provide one with minimum protection incase of obvious and unexpected accidents of mishaps in the process.
Now to the assignment,I decided to go shopping on the web for creative works in composites and I somehow found a simple design I could work with due to timeline. I settled on modifying a mold with a curvy surface. Honestly I didn't have any functionalities in mind so I just went ahead.. My intent was to get a first experience since it was my first time.
Here we go, the steps are as follows:..
Remember the materials I mentioned above I chose to work with:

I did two projects of which the 2nd was quite successful than the prior..
Hahaha..the first project backfired big time whereby I ended up with burnt fingers due to poor handling of hydrostone....this is how I did it...
>>Breather
>>Burlap Sheets (Yute)
>>Peelply
>> Epoxy resin
>> Hardener
>> Foam
Steps:
- Place the foam on the ShopBot, using double-sided tape to prohibit movement. Mill the mold.
- Cut the layers of material (peelply, breather, burlap) into the desired shape.
- Mixing ratio is 2 parts epoxy, 1 part hardner.Piece of advice unless stated otherwise always try to add liquid into particles not the opposite.
- Composite materials consist of several layers. In this case the sequence of layers is:
>> The Mold
>> Peelply
>> 2 layers of Burlap
>> A layer of peelply (with no holes)
>> Breather.
- Dip the layers of burlap in the mixture. Make sure you squeeze out/ drain the excess of resin before applying the layer onto the previous one (to keep the resin from leaking through the pleeply layer and protect the machine. Cover all sides of the material, making sure there isn't any exposed parts that could potentially stick to the machine.
- Vaccum bagging which takes approximately 6 hours.
Several challenges were due to take place or rather occur in the process:
>> I made the mistake of mixing without proper gloves I almost lost finger nails hence the precaution always wear protective garment before commencing. >> I cut the burlap sheets way bigger than needed, so I had to cut/shape the excess burlap to size after it fully dried out. Always cut the materials fit the mold and not more. Doing so saves materials and helps to protect the machine from any leaking resin. Make sure the burlap is covered with peelply and breather from all sides. >> Accumulation of resin were spotted on one of the corners of the model due to adding too much resin to a burlap layer. Make sure you drain the burlap by squeezing out as much resin as possible. >> It would be a good idea to add more curves to the design. In my case, I wanted to test the material's fuctionality before designing/ fabricating something more complex.

The second project found me wanting to utilize my feet alone hence the amusing idea of creating skates...

I decided to work on a composite made of bamboo, fabric and epoxy resins. I quite manage to do it with a deck for a skateboard...

Alright here are the file ready for download and aldo design files:>..


>>> Download original DXF files design in CorelDraw with minor Inkscape editingas per the assignment

>>> Download original 3dM files design in rhino v5 and rendered in blenderas per the assignment



The design was made by drawing many curves in the x and z directions and some others in the y and z directions. Then I created a surface from them. Once I had that surface, I could quite simply acquire/retrieve the 3d files to do the mold in the shopbot and the traces to cut the bamboo in the laser cutter.I thought of using manual means but I thought why not go digital.



Once the fold mold was milled and the bambo cut, I duly prepared the rest of materials deemed necessary in the process of creating my composite.



I enacted a piece of fabric so as to capture the rogue epoxy resins in between the bamboos. Part of the fabric`s use was to let through some epoxy resin so as to enable recyclabity of the composite or rather epoxy. And a non-adhesive material which would aptly capture the excessive epoxy.



Then I mixed the epoxy resins and the hardener and put it in the fabric and in the bamboo. I made the sandwich of all the materials and put it in a vacuum bag.



I supposed the air was meant to push the bamboo to curve/bend but I was in for a surprise. I waited for 8 solid hours only for the resin to give me the same blank appearance nevertheless it was still my first time so I was quite satisfied.



I did quite some protection aspects which involved using a finisher and some wood glue to reinforce weak areas...also sunflower oil came in handy due to its cohesiveness..




I was so happy I took some time to jump 10 times in the lab even though I couldn`t see much that had come out of the process..it was really fullfilling either way...Thank luck castor wheels were in plenty in the lab I took several so as to be ready to take a flight..

....

HEY don`t laugh I already told you the epoxy resin didn`t do a very nice job but there`s always next time for perfection..So the flatness and smooth curvature was all I could achieve...