科研之友
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摘要
Lubrication plays an important role in reducing prosthetic wear. Time-dependent elastohydrodynamic lubrication simulation for total knee replacements was carried out under physiological loading and motions of a gait cycle. In numerical implement, a simplified ellipsoid-on-plane configuration was introduced to represent the artificial knee joint. Load and motions came from ISO standard, and both anterior-posterior displacement and flexion-extension rotation were considered to realize sliding and rolling motions of the knee. The governing Reynolds and elasticity equations were solved simultaneously using the multigrid technique. The elastic deformation was calculated based on the constrained column model. The results show that: (i) under the combination of entraining and squeeze-film actions throughout the walking cycle, the predicted central film thickness decreases during stance phase and keeps a relatively larger value in swing phase; (ii) high joint conformity helps to reduce hydrodynamic pressure and increase lubrication film thickness; (iii) the thickness of ultra-high molecular weight polyethylene layer and its properties also have influence on the lubrication performance in artificial knee replacement. Based on the aforementioned EHL analysis, potential surface damage of knee implants can be further evaluated.
