An Investigation of the Fatigue Induced Failure Modes of Fiber/Elastomer Composites as Bearing Surfaces in Total Hip Joint

This research represents a fundamental study of the failure mechanisms observed in fiber reinforced elastomeric bearing surfaces. The specific focus of this research is the failure of one or more of the bearing surfaces in a total hip joint replacement. The goal of this research is to develop a better fundamental understanding of all of the complex modes of failure in bearing surfaces which can then be used to design new materials with sufficient longevity for use in a total joint replacement or other bearing applications. It has been proposed to use elastomeric composites as artificial joints bearing surfaces to increase their fluid film lubrication and therefore reduce their failure attributed to wear mechanisms. The fluid generated between the surfaces supports part of the load and prevents direct contact of the bearing surfaces. However, permanent deformation or failure of elastomeric composites has been observed following debonding between fiber and matrix. It is hypothesized that heat generated at the contact between the elastomeric composite and the reciprocating counter part contributes significantly to failure of the elastomer. A preliminary study was conducted to determine the effectiveness of a tribological experimental model to verify this hypothesis. The coefficient of friction between UHMWPE and metal and an unreinforced polyurethane elastomer bearing against metal was measured using reciprocating motion. The next phase of this project will consist of using this experimental model to analyze the effect of friction on the failure of elastomeric composites composed of polyurethane matrix and fibers