STUDY ON MIXED LUBRICATION MECHANISMS OF FRACTAL SURFACES

本课题的目的是基于表面粗糙度的分形表示，为理解全流体动力到混合润滑状态下的油膜形成和接触机理奠定理论基础。进行了规则微槽的混合润滑试验，用荧光显微镜测量了膜厚和微孔，并对分形表面的流体动力润滑进行了理论分析。1.采用光刻制作的规则微槽的铜试件进行混合润滑试验，结果表明，当槽的纵向与运动方向的夹角在0到90度之间变化时，摩擦系数和部分接触开始时的膜参数在中角出现最大值。2.用喷丸制造的随机粗糙度的玻璃盘和钢球进行点接触混合润滑试验。从FLORE…上的荧光图像和反射图像球/盘结构的滑动和滚动试验表明，在较低的宏观动压下，表面会产生微孔洞，而磨合对表面粗糙度的修饰会导致局部动水压力的增加，从而导致微孔洞的生长。4.建立了基于摄动法的分形面流体动力润滑理论，揭示了分形面对流体动力润滑的影响。利用傅立叶滤波法生成的模拟轮廓线对无限宽倾斜滑动轴承进行了数值计算，计算结果与理论吻合。5.采用512×512网格尺寸对有限宽模拟表面倾斜滑动轴承的压力进行了数值计算，结果表明了分形结构对轴承承载能力的影响。较少

This project was aimed at establishing a theoretical ground for understanding mechanisms of film formation and contact in full hydrodynamic to mixed lubrication regimes on the basis of fractal representation of surface roughness. Mixed lubrication tests with regular microgrooves, measurements of film thickness and microcavity using a fluorensent microscope, and theoretical analyzes of hydrodynamic lubrication for fractal surfaces were conducted.1.Mixed lubrication tests using copper specimens with regular microgrooves made by photoetching revealed that, when the angle between longitudinal direction of the grooves and the direction of motion was changed between 0 and 90 degrees, the friction coefficient and the film parameter for the onset of partial contact took on maximum at intermediate angles.2.Point contact mixed-lubrication tests were conducted using a glass disk and steel balls having random roughness made by shot-blast. From fluorescent images and reflection images on the fluore … More scent microscope, decrease in the relative gap between the surfaces and increase in local asperity contact areas were obtained quantitatively.3.Sliding and rolling tests were conducted with the ball/disk configuration, which showed that microcavities are generated under low macroscopic hydrodynamic pressure, and that modification of surface asperities by running-in cased increase in local hydrodynamic pressure leading to growth of microcavities.4.A theory of hydrodynamic lubrication of fractal surfaces based on a perturbation method was established to show effects of fractal surcture on hydrodynamic lubrication. Numerical computations for an infinitely-wide inclined slider bearing were also conducted using simulated profiles created with the Fourier filtering method, and the results agreed with the theory.5.Numerical computations of pressure for a finite width inclined bearing with simulated surfaces were conducted using a grid size of 512X512, which showed effects of fractal structures on load carrying capacity of the bearing. Less