Design and Analysis of a Composite SACH Foot: Experimental Validation and Finite Element Modeling

Abstract

One of the critical components in the rehabilitation of lower limb amputees is the prosthetic foot. The solid ankle cushion heel (SACH) foot is commonly prescribed to patients due to its ability to reduce impact loading at heel strike, as well as its durability and cost-effectiveness. This research focuses on developing a composite SACH foot using two different polymers. The keel was constructed from Nylon fiber, while the shell, designed to resemble an amputee's foot, was made from Polyurethane (PU) foam. The keel functions as a surrogate for the amputee's bone and is therefore specifically designed and embedded within the shell. The developed SACH foot underwent static testing according to the ISO 10328:2016 standard at various angles. Additionally, it was modeled and analyzed using the finite element method (FEM). Material tests were conducted on both the keel and shell to establish their material models for FEM. The finite element analysis (FEA) demonstrated an average error of less than 15.22%. Moreover, the FEA provided insights into the deformation and stress experienced by both the keel and the shell. This detailed investigation into the structural behavior of both SACH components offers valuable guidance for the future design and development of composite SACH feet.