Study of aspherical femoral head aiming long-life artificial hip joint

为了改善人工关节的润滑状况，有必要了解接触应力的大小。在本研究中，推导了一些参数方程来计算保形接触中的接触压力。计算结果与有限元计算结果吻合较好。研究了干润滑条件下接触压力分布对聚合物轴承摩擦系数的影响。进行了板上销滑动试验和苏打摆式滑动试验。研究发现，在润滑条件下，接触压力分布对摩擦系数有显著影响。当接触压力较低的侧向前滑动时，摩擦系数变小。干燥条件下的摩擦系数与滑动方向无关，与接触压力分布无关。利用倒向滑动试验装置，研究了表面磨削方向与滑动方向不同对摩擦系数的影响。结果表明，在与磨削方向垂直的滑动方向上，摩擦系数最小。相反，当滑动方向与磨削方向平行时，其最大。在此基础上，研究了在固定坐标系和运动坐标系下引入角速度的滑动轨迹计算方法。

To improve lubricating condition in artificial joint, it is necessary to know the magnitude of contact stress. In this study, some parametric equations were derived to calculate contact pressure in conformal contacts. The results obtained from the equations were confirmed to agree with that of FEM calculation.Influence of contact pressure distribution on the coefficient of friction was investigated for some polymeric bearings in dry and lubricated conditions. Reciprocal pin on plate sliding test and Soda pendulum type sliding tests were carried out. It was found that the contact pressure distribution has a significant effect on the coefficient of friction in lubricated condition. The coefficient of friction became smaller when the pin was sliding with the lower contact pressure side ahead. The coefficient of friction in dry conditim does not depend on sliding direction regardless of contact pressure distribution.The effect of an orientation of grinding direction of the surface to sliding direction on the coefficient of friction was also studied by using a reciprocal sliding tester. It was found that the coefficient of friction became smallest in the case of sliding direction perpendicular to the grinding direction. Conversely, it became largest in the case of sliding direction parallel to the grinding direction. Furthermore a method of slide track calculation was studied by introducing angular velocity in a fixed coordinate system and a moving coordinate system as well.