Progressive failure analysis of laminated composite femoral prostheses for total hip arthroplasty.

In this research program, a numerical method was developed to predict the progressive failure of a thick laminated composite femoral component for total hip arthroplasty. A 3-D global/local technique was used to capture the overall structural response of this system while also enabling the 3-D ply level stress state to be determined efficiently and accurately. Different failure criteria and different material degradation models were incorporated as individual subroutines in the numerical method, giving it the flexibility to model a wide range of materials and structures. Numerical modeling was also conducted to design experimental test methods for component fatigue testing that closely simulate in vivo loading conditions. Parametric studies were then conducted with the numerical model of the experimental system and the results were compared to the actual experimentally determined damage behavior of fabricated laminated composite femoral component to assess which parameter set most accurately predicted the actual damage development behavior. The best fitting parameter set was then applied to the failure problem of the composite hip prosthesis implanted in an anatomically modeled femur to predict in vivo performance. This work provides a ply level understanding of the damage behavior of laminated composite femoral components and a numerical tool which can serve as a guide for the design of fatigue resistant implants made from composite material for this and other implant applications.