Desenvolvimento de próteses para membros inferiores híbridas em impressão 3d/fibra de carbono

Abstract

Aiming at the rehabilitation of individuals with lower limb amputations, prostheses are used to provide users with conditions for greater comfort and functionality, enabling walking and the execution of daily tasks. Prostheses for transtibial amputation are devices used in the region of the missing lower limbs, located below the knee joint, namely the tibia, fibula, and foot. A prosthetic foot is commonly manufactured in molds using the autoclave process, aiming at mass production, which prevents the user from obtaining a personalized model. Considering obtaining a customized and low-cost prosthesis, the present work seeks to design, manufacture, and analyze the feasibility of a new concept in prosthetic feet. The project consists of performing 3D scanning of a real human foot to obtain an editable design model. The model was then prepared for the development of the structural part of the foot, in carbon fiber/epoxy. The structural part of the foot was worked on in a finite element computational program to obtain structural responses (stresses, deformations, and Tsai-Wu failure index). After numerical simulation, full-scale models were printed with the assistance of a 3D printer and thermoplastic polyurethane (TPU) filament. The printed foot then received an internal structure (reinforcement) manufactured in polymer matrix composite reinforced with carbon fiber through a manual manufacturing process. After the fabrication of the models, static compression mechanical tests were performed, following ISO 10328:2016 standard, to verify the structures proposed in this work. The results of the mechanical tests were compared with those of the numerical simulation to obtain correlation values, showing that the correlations between numerical simulation and mechanical tests were satisfactory. Additionally, it was observed that the test in the heel region exceeded the standard requirements by 358%. However, the test performed in the forefoot portion failed when a load of 20% of the target load was applied, due to defects originating from the composite manufacturing process. The results indicate that the concept is highly promising, being a viable alternative in the field of lower limb prosthetics.