Developmental study of a 3D prosthetic foot using finite element analysis

The most popular type of prosthetic foot is the energy storage and return (ESAR) foot, which provides stability and balance during gait. The study focuses on the development of an ESAR prosthetic foot using various types of acrylonitrile butadiene styrene (ABS) material. The primary aim was to enhance stability and balance during gait. Two strategies were implemented: modifying the material to improve its mechanical properties and altering the foot design. The findings revealed that design changes were more critical to the model's success than material adjustments. Finite element analysis (FEA) was used to compare the stress responses of ABS, carbon fiber polylactic acid (PLA), and polyethylene terephthalate glycol (PETG) during gait cycles. During the heel strike (HS) phase, stress values were measured as follows: ABS Plus at 11.562 MPa, carbon fiber PLA at 11.723 MPa, and PETG at 1.9806 MPa. Notably, the total deformation was less for carbon fiber PLA and PETG compared to ABS Plus, with values recorded at 1.9671 mm, 1.7445 mm, and 0.55776 mm, respectively. The most successful design iteration (design F) demonstrated optimal results with a total deformation of 4.7254 mm, strain energy of 0.1863 mJ, and von Mises stress of 19.57 MPa, achieving a safety factor of 1.584 overall. Conversely, other designs, particularly design E, exhibited high stress levels (42.816 MPa) and safety factors below the acceptable threshold of 1.5. Dynamic analysis showed poor performance under fatigue testing, with safety factors ranging from 1.0368e-7 to 8.9274e-8 indicating a high risk of structural failure. Overall, the study highlights the critical need for effective design modifications in prosthetic foot development to ensure safety and functionality for amputees.