STIFFNESS ANALYSES FOR THE DESIGN DEVELOPMENT OF A PROSTHETIC FOOT

Abstract

There are 110 million uncleared landmines in 64 countries around the world (OSCE, 1998). There have been over 1 million landmine victims since 1975, and the number is growing at a rate of 26,000 new victims each year (One World International, 2001). One solution, the Niagara FootTM (Niagara Prosthetics and Orthotics, St. Catharines, ON, Canada) (Fig. 1) is directed towards amputees in developing countries like Thailand and El Salvador. This prosthetic foot is low cost and highly durable, since it is made of a polymer from DuPont Delrin�. Structural stiffness is a force versus deflection relationship that is a result of the geometry, material and loading of the structure. If the foot is too stiff it is unresponsive. If the foot is too flexible, the person may fall over. To evaluate the stiffness performance of the Niagara FootTM a repeatable testing procedure is needed. There are two goals to this project: to investigate the repeatability of the mechanical test and to develop an accurate finite element (FE) model validated against the test results, such that the stiffness of subsequent foot designs can be simulated before the foot is manufactured.