Year

2014

Season

Fall

Paper Type

Master's Thesis

College

College of Computing, Engineering & Construction

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Engineering

NACO controlled Corporate Body

University of North Florida. School of Engineering

First Advisor

Dr. Alexandra Schonning

Second Advisor

Dr. Alain Kassab

Third Advisor

Dr. Stephen Stagon

Department Chair

Dr. Murat Tiryakioglu

College Dean

Dr. Mark A. Tumeo

Abstract

In this study, a non-linear Finite Element (FE) model was created and analyzed to determine the pressure distribution between the residual limb and the prosthetic socket of a transfemoral amputee. This analysis was performed in an attempt to develop a process allowing healthcare providers and engineers to simulate the fit and comfort of transfemoral prosthetics to reduce the number of re-fittings needed for the amputees. The analysis considered the effects of interference due to insertion of the limb into the prosthesis, referred to as donning, and also the effects due to the body weight of the amputee. A non-linear finite element static implicit analysis method was utilized. This analysis implemented multiple finite element techniques, including geometric non-linearity due to large deflections, non-linear contacts due to friction between the contact surfaces of the residual limb and the socket, and non-linear hyper-elastic material properties for the residual limb’s soft tissue. This non-linear static analysis was carried out in two time-steps. The first step involved solving the interference fit analysis to study the pre-stresses developed due to the effect of donning. The donning process results in soft tissue displacement to accommodate the internal geometry of the prosthesis. In the second load application time-step, an additional load of half the person’s body weight was applied to the femur. The maximum normal stress (contact pressure) of 84 kPa was observed due to the combined effect of the donning procedure and body weight application, comparable to the studies performed by other researchers. The procedure developed through this work can be used by future researchers and prosthetic designers in understanding how to better design transfemoral prosthesis.

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