An Experiment Study of Acoustic Emission Generated by Dynamic Fluid Asperity Shearing

The dynamic responses of hydrodynamically lubricated surfaces have attracted many researchers for the sake of improving both the lubrication performances and online lubrication monitoring. To gain insightful understandings of dynamic interactions in a fluid lubricated joint that are the fundamentals of many key mechanical components such as bearings and seals in the engine, a series of engine lubricants were tested in a cone-plate rheometer and the corresponding acoustic emission (AE) signals are acquired to monitor the dynamic interactions of tribofilm shearing with surface asperities. The observations show that the AE measurements are sensitive to the change of lubrication conditions, specifically shearing rates. A greater shear rate can excite a wider frequency bandwidth and stronger AE signals. This AE response with respect to the engine lubricants samples can be explained by the dynamic fluid-asperity shearing model. These findings provide important guidelines for analysing the online measured AE signals from complex machines.