My goal for the 3Bio4 design project was to design a prosthetic arm. When researching online I found
inspiration in an example by the Shirley Ryan AbilityLab. This arm was created to solve the issue of prosthetic
limbs being designed for the 50th percentile male and therefore being too large for many patients. The arm is
therefore scaled for the 25th percentile female. On further research I noted that most prosthetic arms are
designed to support approximately 9kg of mass held in the hand. I aimed to increase this maximum load
dramatically by redesigning the frame of the forearm. Instead of a central tube, I designed an external chassis
which could support a large load while being made of a cheap material which would allow for an easy
manufacturing process. After running loading simulations on Solidworks, I chose cast aluminium.
My final forearm chassis design successfully resisted a load over ten times the average maximum prosthetic
arm load. With 900N applied to the wrist end and anchored at the elbow, the full component remained below
the yield stress of the material.
Each finger has independent movement and each one is limited to not bend backwards or touch the palm. The
palm is the base part. The wrist allows for vertical and rotational movement. The elbow joint rotates in the range of approximately 15 to 90 degrees.