After googling for a while on interesting cooking experiments that people do with the lasercutter, I decided to go conservative this wildcard week and stick to learning a well-defined process.
I have been interested to know more about composites because they are used to make prosthetics and orthotics. They could also be used to make portable assistive devices like light and strong adaptive chairs. However, I wanted to start with something easy and useful for my final project.
I started designing the beam from which the kid's head is suspended in the dynamic head support system. I thought that if the beam is in composite material, it would be stronger to bear the weight of the head. I had to rule this idea out because the instructors said that for this assignment I have to make something bigger (in the order of ft^2). I then tried designing a contoured backrest that can be strapped to any chair but gave up and started making a simple tray that can be slid into the slots in the side panels of the adaptive chair that I had milled for my shopbot assignment.
For some basic theory on composites, check this Wikipedia page. The property of a composite material is different from that of its constituent materials, which are the matrix (resin) and the reinforcement (fibre). The properties of a composite mostly resemble that of the reinforcement (fibre). The resin holds the fibre together and helps it to take the desired shape. Resin also helps to spread the mechanical load from the fibre to the entire composite material.
Check the video below for what I made this week:
We made test coupons with different orders and orientations of fibre layers, to test which gives the strongest composite.
1. Layers 1 and 5 - Linen (90 degree orientation) and layers 2,3,4 - Jute (45 degree)
2. Layers 1 and 5 - Linen (90 degree orientation); layer 3 - Jute (45 degree); Layers 2,4- Jute (90 degree)
3. Layers 1 and 5 - Linen (90 degree orientation)and layers 2,3,4 - Jute (90 degree)
The coupon with the three jute layers at 45 degree orientation was adjudged to be the strongest, based on a bending test by three different people in the lab.