Design and verification of a finite element analysis model for predicting deflection of actively actuated prosthetic sockets

A lower limb prosthesis provides assistance to its user in both ambulation and stationary support. The lower limb prosthesis consists of a socket, which interfaces with the residual limb, a pylon, attachment hardware to secure the pylon to the socket, and a prosthetic foot. For the prosthesis to be effective, the socket must be comfortable, functional and aesthetically appealing, usually in that order. Lack of comfort and fit can cause movement problems and health issues. The residual limb of the amputee changes its volume throughout the day and in order to maintain comfort a socket must be able to adapt to these volume changes. Previous research has resulted in the development of concepts for inflatable prosthetic sockets capable of addressing this need. The concepts rely on laser sintering (LS) to manufacture the parts. This research focuses on the development of a finite element analysis (FEA) method to assist in the design of adaptive sockets. The FEA can be used to predict the pressure-deflection curve of a given socket design. The FEA method was verified by experiments using LS manufactured test specimens. Results from FEA simulations indicate that the LS-manufactured sockets will achieve the desired deflection (~0.1 in) for relatively low pressures (< 10 psi), providing evidence for the feasibility of this approach.