Abstract:The effect of abrasive particles on the tribological properties of lubricating oil was studied by experiments and simulation.The friction coefficient of lubricating oil containing abrasive particles was measured by micro-nano indentation/scratch test.At the same time,the boundary lubrication system model was established,and the molecular dynamics (MD) method was used to simulate the density distribution and compression ratio of the lubricating oil films along the film thickness direction under different loads.The shear velocity in opposite directions was applied to the upper and lower solid walls of the system,and the stress,friction force and positive pressure and friction coefficient of the solid surface were calculated.The dynamic behavior characteristics of the wear debris with different particle sizes were analyzed.By reducing the number of lubricating oil molecules,the friction performance of the abrasive lubrication system under the condition of lack of oil was explored.The results show that the MD simulation value of friction coefficient is consistent with the experimental value.The presence of abrasive particles will reduce the compression rate of the oil film,and the presence of abrasive particles under high load will destroy the delamination of the oil film and affect the density distribution near the abrasive particles.The friction coefficient of the lubricating system containing small particle size abrasive particles is smaller than that of the lubricating system containing large particle size abrasive particles,indicating that the phenomenon of abrasive particles gathering and growing will deteriorate the lubricating performance of lubricating oil.There are both rolling and sliding during the shearing process,and the lubrication system with small particle size abrasive particles shows greater angular velocity fluctuation during the shearing process.With the increase of load,the angular velocity of abrasive particles and the fluctuation amplitude decrease.Under the condition of oil shortage,the abrasive particles will deform and break during the extrusion shear process.