Sean A. Coots

Abstract

Conventional artificial hip joints are characterized by inadequate `wedge film' lubrication due to cyclic non-reversing loading and low frequency oscillatory ball motion. A novel `squeeze film' design concept is presented which employs elastic restoring action and ellipsoidal cup geometry to enact separation of the bearing surfaces and improve lubrication behavior. Lateral and in-line design configurations were developed and analyzed using established finite element lubrication models with realistic gait cycle and bearing design specifications likely to be found in practice. An Archard-based wear formulation that relates contact pressure and sliding distance to linear wear depth was applied to the design configurations utilizing ANSYS to investigate the wear characteristics of the novel implant design. From a lubrication perspective, it was found that significantly larger minimum film thicknesses and significantly smaller maximum film pressures are predicted over the stance phase when compared with conventional designs, while complete reformation of the lubricant film is predicted over the swing phase of the gait cycle. From a wear perspective, it was found that low-modulus elastic elements with bonded high-modulus metal coatings offer significant improvement in volumetric wear rates and maintain acceptable levels of linear wear rates when compared with conventional implant geometries.

Library of Congress Subject Headings

Artificial hip joints--Design and construction; Lubrication and lubricants--Testing; Mechanical wear

Publication Date

7-22-2014

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Stephen Boedo

Advisor/Committee Member

Steven Day

Advisor/Committee Member

Steven Weinstein

Comments

Physical copy available from RIT's Wallace Library at RD549 .C66 2014

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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