COMPOSITE HIP-PROSTHESIS DESIGN .1. ANALYSIS

An investigation was performed to study the mechanical performance of fiber-reinforced composite hip prostheses in a femur. The main objecti ve of the study was to evaluate the effect of fiber orientation of a c omposite femoral implant on the response of the surrounding femoral bo ne. A three-dimensional finite element analysis was developed for anal yzing a composite implant in the femur. A three-dimensional composite element was proposed to take into account ply drop-off due to a change of cross-section of the composite implant. The element could accommod ate multidirectional layers and tapered composites. The material prope rties of the composite were treated as anisotropic and inhomogeneous w hile the properties of femoral bone were treated as anisotropic and ho mogenous. All the materials were assumed to behave linear-elastically. The thermoplastic graphite/PEEK material system was selected for the study. In this presentation, as the first part of the study, the devel opment of the finite element analysis will be described. Numerical cal culations were generated and compared with existing data and numerical results available from studies related to metal hip prostheses in the literature. Experiments on the composite hip implants were also condu cted for further verification of the analysis and the computer simulat ions. In Part II, using the finite element code, an extensive study wa s performed to evaluate the stress/strain distributions, micromotions, and strain-energy density of the surrounding femoral bone, which have been related to initial fixation and long-term stability of the prost hesis in a femoral bone. Numerous fiber orientations were studied, and results of the calculations were compared with those generated by the prosthesis made of cobalt alloy and titanium alloy. (C) 1998 John Wil ey & Sons, Inc.