Space grease lubrication modeling: A discrete element approach

The tribological behavior of space grease is investigated with the Discrete Element Method. In the first step, the grease is described as a collection of particles of two kinds (oil and PTFE) in interaction. The development of the Grease Discrete Element Model (GDEM) used here, is based on rheometer-like characterizations. In the second step, the GDEM is subjected to tribometer-like conditions to investigate grease flow mechanisms and the role of the thickener (PTFE) in lubrication. The tribological behavior of grease seems to be controlled by the coupled influence of both granulometric (thickener particle sizes) and physico-chemical (interaction law) parameters. These results provide the starting point for identifying the parameters on which to act to reformulate greases.