人类天然关节和人工关节润滑机理的探讨

将关节接触简化为两弹性椭球体的接触,应用弹性流体动力润滑(Elasto-Hydrodynamic Lubrication-EHL)理论研究人类天然关节和人工关节的润滑状态.给出适用于静载、富油、低弹性模量材料的最小膜厚公式H_(min)=2.12(1-0.984e~(-0.579k)U~(0.579)W~(-0.224).由于关节实际上承受变载荷,挤压膜对关节的润滑有重要作用,为此本文进而提出称谓"动载弹性流体动力润滑"的关节润滑模型.应用这个模型,研究了人在行走时髋关节的润滑情况.研究结果表明,在一个行走周期内,髋关节的表面约三分之一时间处于弹性流体动力(Elasto-Hydrodynamic—EHD)润滑;三分之一时间处于混合润滑;其余时间处于边界润滑.这就是说,润滑状态是随时间而变化的.

On the Lubricaton Mechanism of Natural Human Joints and Artificial Joints

With the joint contact being simplified into a contact of two elastic ellipsolids, the lubrication of a natural human joint and that of an artificial joint are studied on the basis of the Elasto-Hydrodynamic Lubrication (EHL) theory. A minimum film thickness formula has been given as Hmin=2.12 (1-0. 984e~(-0.579k)U~(0.595)W~(-0.224) which is suitable for materials of low elastic modulus provided that they are steadily loaded and fully flooded. Since the loads acting on the joints are variables and the squeeze film plays an important role in joint lubrication, a lubrication model of the joint is proposed, which is called "unsteadily loaded elasto-hydrodynamic ubrication." With that model the lubrication of a natural hip joint under the walking state is studied. The results indicate that for about one third of the time the surfaces of a hip joint are subjected to Elasto-Hydrodynamic lubrication; for one third of the time in a state of mixed lubrication and for the rest of the time in a state of boundary lubrication. That means that the lubrication changes with the time.