Prosthetic Knee Joint (2017)
#Solidworks #FEA #3D Printing
The purpose of this project was to design a new prosthetic knee joint that is easy to use, lightweight, low cost, and free of sharp corners and pinch points. The knee joint is supposed to support the approximate weight of a 250-pound male and designed to withstand a maximum load of 1250 pounds. As a result of many natural and man-made disasters, many people are left with impaired mobility when one or both knee joints are amputated. Cheap and effective prosthetic knee joints are desired to enable the disabled population to afford the prosthetic and enjoy close to natural walking once again. In this report, a novel knee joint utilizing concepts from the field of compliant mechanisms is proposed. Specifically, the use of a compliant rolling element (CORE), which simulates a revolute joint through two cylindrical bodies constrained by flexible bands/strips (flexures), was investigated to produce the motions of the knee. Using Solidworks, a 3D model of the prosthetic knee joint was created and tested by inputting the design loads acting on the prosthetic joint while standing. To analyze the fatigue resulting from the loads, FEA analysis was performed to determine the stresses experienced by the knee joint. This result was compared with the conclusions from rigorous hand calculations investigating the stresses on the joint components. To model the cost-effectiveness of the knee joint, different materials, manufacturing operations, and sales strategies were considered. The prototype cost of the CORE knee prosthetic was found to be $646.13 per unit for a working model of the design. Manufacturing processes required to build a commercial-grade CORE knee prosthetic is a combination of metal stamping, extrusion, die casting, and injection molding. The novel CORE knee design can be implemented for all above-knee amputees around the world and will allow them to regain their natural knee mobility. To visualize and test the design, a 3D-printed physical joint was made for the primary proof of concept which is shown in the video below.