Effects of Bingham-Visco-Elasticity of Greases on Creation and Disappear of Core in Fluid Film Lubrication

由于润滑脂在实际应用中比油等其它润滑剂具有更好的润滑性能，因此本课题的目的是阐明润滑脂的宾汉粘弹性对液膜润滑核心的产生和消失的影响。本课题假设了一个由一个滑块、两个非线性阻尼器和两个非线性弹簧组成的流变方程，本文用旋转和振动流变仪对各种市售润滑脂进行了实验研究，在上述流变方程和液膜润滑理论中引入屈服应力张量，导出了直角坐标系和柱坐标系下的润滑方程，并考虑了芯部液膜的形成和消失与时间的关系。由于润滑脂的宾汉特性，这些润滑方程无论有无核心都是不同类型的。另一方面，利用步进挤压推力轴承试验机，在楔块和挤压作用下，用摄像机测量核心的轮廓。阐明了流体膜润滑中润滑剂的宾汉粘弹性对润滑脂成核的影响。

The object of this project is to clarify an effect of Bingham-visco-elasticity of greases on creation and disappear of core in fluid film lubrication, because a grease in used in practice due to easy lubrication system as compared with that by other lubricants such as oil.A rheology equation supposed in this project, which consists of one slider and two nonlinear dashpots and two non-linear springs, is investigated experimentally for the various kinds of commercial grease by using rotational and vibrational rheometer.By introducing yield stress tensor to the above rheology equation and to fluid film lubrication theory, lubrication equations are derived for Cartesian and cylindrical coordinates by considering time dependence on creation and disappear fo core fluid film. These lubrication equations are different types whether core occurs or not, due to Bingham characteristics of greases.On the other hand, by using step squeeze thrust bearings tester with such greases, profiles of core are measured by camera under wedge and squeeze action. Characteristics of Bingham-visco-elasticity of lubricants on the core formations of greases in fluid film lubrication are clarified.