One of the professors at Cal Poly was born as a transradial amputee and has never used a prosthesis before. He remains active, but finds it difficult to exercise the muscles in his left arm. Our team was tasked with designing and fabricating a prosthetic socket and set of attachments. As an individual, my goal was to design and develop the method for manufacturing the socket.

Goal

3D Printing

Design Process

3D printing played a pivotal role in developing socket assemblies, ensuring precise fit, functional integrity, and compatibility with composite molding processes. Complementing this, 3D scanning was employed to accurately capture the arm’s contours, enabling anatomically tailored designs. The additive manufacturing workflow supported rapid prototyping and accelerated iteration cycles.

Socket Fabrication Method

Similar to industry standard methods for wet layup socket manufacturing were used to make the socket. A mold is placed on a vacuum jig, layered by a PVA bag, composite fiber, and PVA bag. The epoxy is then poured over top and pulled into the fiber by the vacuum. I designed and fabricated a vacuum jig to meet our fulfill the process functions.

I designed the mold and grace plate to auto-align to each other by implementing a key-way system. This keyway also allowed for ease of mold removal from the cured socket.

Top Skills Utilized

• Prosthetic Design

• Composite Design

• Biocompatibility Design

• 3D Printing

• SolidWorks

• Process Development

Takeaways

I learned about composite design, prosthetic design, and how to take advantage of anatomical suspension for supporting the socket on the arm. If I were to do this project again, I would spend time developing the inner socket, as this will heavily affect the comfort for the user, and triceps cuff, as this holds the socket on the arm during heavy pulling loads. I'd start by developing 3D printed interior sockets with high elastic plastics, or injection molded silicone. For the triceps cuff, I would test the maximum load at the hinge point on the socket and modify the cuff for optimal comfort to the user.

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