粒度及其分布对颗粒介质摩擦副摩擦学特性的影响

Influences of Particle Size and Size Dispersion on Tribopairs Lubricated by Particulate Media

利用基于离散单元法的数值模型对颗粒粒度及其分布开展了理论研究,对宏微观尺度的力、能量、摩擦等特性进行了探讨。离散单元法的理论基础是非连续介质力学,这可使颗粒介质摩擦副在力学及摩擦学特性上的非连续、非均匀特点获得较好的展现,可以判断其内部存在的运动和力的随机性及结构突变。较大粒径的颗粒具有更大的承载力和摩擦因数,更容易形成准直线形的强力链,导致摩擦特性的随机现象和结构突变增加。粒径的均匀分布和高斯分布使颗粒间的力分布趋向均匀,摩擦副运动更加平稳,摩擦因数有所减小。

The experimental methods and continuum mechanics,which well be used in hydrodynamic lubrication,is no longer effective in studying the particulate media tribopairs.The discrete element method（DEM） was adopted to simulate the influence of particle size and size dispersion on the force,energy and friction characteristics in macro and micro scale.Benefit from the discontinuous mechanics,which was the theoretical basis of DEM,the discontinuity and inhomogeneity were exhibited well in mechanics and tribology.The randomicity and structural break of the movement and force were concluded.The media with bigger particles takes on a heavier load capacity and higher friction coefficient,and tends to form line-like strong force chain which leads to random behaviours and structural breaks in tribological characteristics.Under the circumstances of uniform dispersion and gauss dispersion,the distribution of load capacity and friction force are more continuous and smooth.Meahwhile,the motion of tribopairs is more stable,and the friction coefficient is lower.