颗粒间摩擦对颗粒流润滑影响的力学机制

颗粒流润滑是一种可用于苛刻工况环境的新型润滑方式，颗粒间摩擦对颗粒流润滑影响的规律和特性是阐明颗粒流润滑理论的关键科学问题，也可以为极端工况环境下颗粒流润滑轴承的设计和参数选择提供技术支持。为了分析颗粒间摩擦对颗粒流润滑系统宏、微观特性以及下摩擦副与颗粒润滑介质间摩擦的影响规律，构建了颗粒流润滑离散元数值模型，并对该问题进行了分析和研究。研究结果表明:颗粒间摩擦对颗粒流润滑系统的减摩润滑特性具有显著影响，下摩擦副和颗粒润滑介质之间的平均摩擦系数会随着颗粒间摩擦的增大而增大；颗粒流润滑系统内的微观配位数和滑动率均随着颗粒间摩擦系数的减小而增大；颗粒润滑介质在摩擦副间隙的宏观流动行为具有明显的分层特性，且宏观流动速度随着颗粒间摩擦的增大而减小，进一步的分析结果表明:颗粒润滑介质的波动速度是直接反映其宏观流动速度快慢的关键性参数。

MECHANICAL MECHANISM OF INFLUENCE OF INTER-GRANULAR FRICTION ON GRANULAR LUBRICATION

Granular lubrication is a new type of lubrication method which can be used in harsh working conditions.The law and characteristics of the effect of friction between particles on granular lubrication are the key scientific issues to clarify the theory of granular lubrication.On the other hand,it can also provide technical support for the design and parameter selection of granular lubricated bearing under extreme conditions.In order to analyze the influence of the friction between granules on the macro and micro characteristics of the granular lubrication system as well as the friction between the lower friction pair and the granular lubrication medium,a discrete element numerical model of the granular lubrication is constructed,and the above problems are analyzed and studied.The results show that the inter-granular friction has a significant effect on the antifriction lubrication characteristics of a granular lubrication system.The mean friction coefficient between the lower friction pair and the granules increases with the increased inter-granular friction coefficient.The coordination number and the sliding fraction in the granular lubrication system increase with the decrease of the inter-granular friction coefficient.The macroscopic flow behavior of the granular lubrication medium in the friction pair gap has obvious stratification characteristics,and the macroscopic flow velocity of granules decreases with the increase of the inter-granular friction coefficient.Further analysis results show that the fluctuation of granular lubrication medium is the key parameter directly reflecting the macroscopic flow speed of granules.