Prototype Presentation Limb-itless Group 4 Chris Bruce, Anna Chen, and Grant Hofmeister

Since the last update Finished wooden mold precursor at the Hobby Shop. Attempted to make plaster mold of the silicone liner. Tested the MED-4091 silicone elastomer. Made prototype with molding rubber.

Hobby Shop Pictures

Prototype Molding process worked marginally well. Plaster used was too soft and cracked easily. Silicone did not reach all parts of the mold. Material used tore easily. Solutions Need to find a higher strength plaster. Process must be modified for MED-4091 and for high temperature curing.

Improvements for Final Product Use better silicone material. Adding fibers in correct orientation. Making durable plaster molds. Modify the molding process for the new material. Accommodate for the pin.

MED-4091 Silicone Material Sample had the properties we were looking for. However it was more viscous than expected. Molding process needs to be modified for this. It will make it easier for fiber alignment. Silicone processing cannot have sulfur or it will hinder the curing process.

Incorporation of Fibers Viscosity of MED-4091 should allow us to hand place the fibers onto mold. Brush thin layer of silicone onto interior mold. Place fibers onto silicone. Brush another thin layer of silicone on top of the fibers.

Mold Experienced difficulty making first plaster mold. In prototype, used wooden model as inner mold. Obtained new plaster with higher strength and faster drying times.

Molding Process For prototype, we poured silicone into the mold which was upright. For final product, we plan to invert the mold so that we can brush onto the inner mold. The outer mold will then be pressed down to complete the process. Then cure the liner at 150 º C.

Next Steps Make silicone sheets with and without fibers. Perform tensile tests. Make new molds. Make new liner with new materials.

Gantt Chart 8- Feb 15- Feb 22- Feb 1- Mar 8- Mar 15- Mar 22- Mar 29- Mar 5- Apr 12- Apr 19- Apr 26- Apr 3- May 10- May 17- Ma y Research meet/call Bruce visit NOPCO Visit Prosthetist Liner design investigate designs design model Material purchases prototyping Testing Tensile testing Field testing Fatigue testing Deliverables Gro up For mal Desi gn Gro up Pro tot yp e Mi d- ter m Gro up Fin al