Stiffness analyses of modified niagara prosthetic feet using finite element modelling

Structural stiffness of a prosthetic foot are based on its shape, type of material, and the attitude of loading. The purpose of this research is to study the effect of S-shape thickness and the type of material on the stiffness of a modified Niagara foot design on the toe and the heel modes of loading. In this study, numerical tests using finite element (FE) method were conducted on four shape models with three different materials. These models are developed by changing the thickness of the upper part of the S-shape “B”. Results indicated that the increase of “B” had increased the stiffness of the foot at the heel mode of loading. Corresponding results were also obtained at only the early stage of the toe loading. Such effect was diminished at the later stages of toe loading due to the closing of the gap between the prongs and the arch. The stiffness characteristics and the force-displacement profiles were consistent with the different design features, indicating that the FE testing protocol is able to capture the mechanical behavior of such designs and can be used to validate the preliminary designs before manufacture. The methodology appointed by this study could be used to clarify new designs of the Niagara foot.