Document Type

Other

Publication Date

4-24-2008

Keywords

atrc, assistive, technology, resource, center, prosthetic, prosthetics, leg, finite, element, analysis, limb, limbs, prosthesis, lower, amputation

Abstract

The Center for International Rehabilitation (CIR) has programs all over the world to provide people in developing countries with the training and equipment they need to supply prosthetic devices to local landmine victims. CIR has created a monolimb, which is a lower limb prosthesis where the socket and shank are molded from a single piece of thermoplastic material. The monolimb can be fabricated on-site with minimal equipment at a low-cost. The shank portion of the device, which replaces the tibial region of the leg, was investigated through a finite element analysis computer program, COSMOSWorks. The current prosthetic device utilized by CIR uses a hollow, cylindrical shape with a rib on the posterior side as the overall shank design. This study combined varying circular outer diameters and rib lengths to determine which combination of parameters contributed to lower overall von Mises stresses and minimal displacement. Four hollow elliptical cross sectional shapes of different minor and major diameters were also modeled and compared to the results of the circular parameter study. The models were input into COSMOSWorks to perform a static analysis on each of the models and the results were displayed through contour plots. The output for each model was analyzed and compared to determine the maximum stresses and overall stress distributions. The displacement present was examined, paying particular attention to the flexibility across the shank, as the displacement can mimic that of natural ankle movement. The ISO Test Standard 10328, which details the necessary structural testing for lower limb prostheses, was used as the basis for testing. The final results compared the overall stress distributions and displacement of each of the models in COSMOSWorks to determine which shape would best withstand the ISO Test Standard 10328 specified load. The results determined that an increase in diameter and rib length positively influences the von Mises stress results and displacement by decreasing their values throughout the shank.

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