Graduation Year

2009

Document Type

Thesis

Degree

M.S.M.E.

Degree Granting Department

Mechanical Engineering

Major Professor

Nathan Crane, Ph.D.

Keywords

Pneumatic permeability, Flexural strength, Three dimensional printing, Prosthetics, Residual limbs

Abstract

Traditional prosthetic socket fabrication is a laborious and time consuming process that involves physical measurements, plaster wrapping of the stump, plaster casting for positive mold preparation, and a thermoforming process. During the mold preparation stage, significant modifications are performed subjectively based on the prosthetist's experience to transmit an optimum load to the residual limb through the socket. Rapid Prototyping techniques have advanced rapidly during the recent decades emerging as a computer aided socket design alternative which promises a potential reduction in the fabrication time, and a more systematic design approach. In addition, 3-D scanning provides accurate and fast virtual replica of the stump which can be imported in CAD environments. Within 3-D CAD software, prosthetists are able to perform modifications precisely and store files indefinitely. This work examines the potential use of ZCorp 3-D printers to directly manufacture the thermoforming mold required for prosthetic socket manufacture. This work analyses the performance of Rapid Tooling molds for thermoformed socket based on three main parameters: pneumatic permeability, flexural strength and wear rate. The traditional material for mold casting, Plaster of Paris, is compared to materials used for three dimensional printing by Zcorp printers: zp130 and zp140 untreated as well as using them with custom and novel post treatments. To obtain the flexural strength of the different materials, three point bend tests were performed in a universal test machine using ASTM Standard D790-03 requirements. In addition, pneumatic permeability tests were performed to cylindrical specimens of the different materials following ASTM Standard D6539-00. Thermoforming tests confirm that Zcorp 3-D printed parts can serve as effective molds for thermoforming of prosthetic socket.

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