Design of a Novel Carbon-Fiber Ankle-Foot Prosthetic using Finite Element Modeling

摘要

Recently, researchers worldwide have made considerable efforts to enhance amputees' quality of life by designing improved prosthetic feet. The ideal prosthetic for this job is that one which seamlessly mimics the functions of the human foot. To achieve this objective, accurate design is thus required. In this paper, a novel design for a carbon-fibre ankle-foot prosthetic is considered. The geometry of the designed ankle-foot prosthetic was created to satisfy a wide range of anthropometric parameters, taking into consideration the available previous designs in the published literature. AutoCAD version 15 was used in this work for modeling and creating the geometry, and ANSYS Workbench software version 16.1 was used for the finite element modelling based on geometry retrieved from the AutoCAD software. The complexity of the suggested design was simplified by partitioning the design into parts according to function. The roll-over shape concept was considered in the current design, which acts as an important tool in the design, evaluation, and alignment of lower limb prostheses and orthoses. Carbon fibre-epoxy composite material was utilised to manufacture a light and high strength prosthetic foot. The current study revealed that the proposed design offered a smooth roll-over shape and good response to energy return requirements in ankle-foot prosthetics, with the keel and heel design behaving as a non-prismatic cantilever beam. The keel and heel thickness require optimisation based on the specific materials used. FE analysis showed successful heel and keel deflections, although inadequate deflection was demonstrated in the vertical loading test. The heel deflected by 29.18 mm under a load of 300 N, while the keel deflected more than 25 mm under 1,230 N, and the deflection under a vertical load of 1,230 N was about 8.1 mm. The strain and stress seen in the three tests were within safe limits, while most of the energy was absorbed in the ankle component of the prosthesis.