Theoretical Investigation in an Artificial Hip Joint under Elastohydrodynamic Lubrication

Abstract

This paper describes the transient analysis of artificial hip joint during human movement under elastohydrodynamic lubrication (EHL) with non-Newtonian lubricants based on a Carreau model. During walking, the load and velocity are varying with time. The numerical schemes employed perturbation method, Newton-Raphson method and multi-grid multilevel with full approximation technique to solve the time-dependent modified Reynolds equation and elasticity equation with initial conditions. The aim of this study was investigated the characteristics of elastohydrodynamic lubrication, profile of film pressure and film thickness profile in human artificial hip joint during human movement. Numerical results show the transient film thicknessincreased and then decreased because of reverse motion. In smooth surface condition, film thickness for Newtonian fluids is slightly higher than the film thickness for non-Newtonian fluid. The amplitude of surface roughness has significant effect on the film thickness,the minimum film thickness decreased when the amplitude of surface roughness increases.