Study on friction characteristics of journal bearings based on thermoelectric potential

Purpose When the bearing operates under static load, the lubrication state of the bearing can be well distinguished by the absolute value of the thermoelectric potential. However, when the bearing operates under dynamic loads, the thermoelectric potential is in an alternating state, fluctuating within a high range, making it difficult to straightforwardly characterize the lubrication state through thermoelectric potential. The purpose of this paper is to find the relationship between the thermoelectric potential and the lubrication state under dynamic load. Design/methodology/approach A thermoelectric simulation is executed using COMSOL Multiphysics to calculate the relationship between thermoelectric potential, load, oil film thickness, oil film pressure and contact pressure. Based on the test rig experimental data, the characteristics of thermoelectric potential in journal bearings under different dynamic loads and operation conditions are investigated and analyzed using feature extraction, clustering and indicator construction methods. Findings The results showed that the low potential percentage and the percentage of bad operation state cluster can effectively characterize the lubrication state of journal bearings under dynamic load conditions. Specifically, in this experiment, when the low potential percentage reaches 15% and the bad operation state cluster dominates most of the time, it indicates that the bearing is in a poor lubrication state. The results of scanning electron microscopy and energy-dispersive X-ray spectroscopy of bearing specimens under different operation states also validated the above analytical results. Originality/value The relationships elucidating the thermoelectric and tribological interactions under dynamic load remain unclear and there is still no efficient method to estimate the lubrication state using thermoelectric potential in previous studies. This paper used simulation and experimental analysis methods to find the relationship between the thermoelectric potential and the lubrication state under dynamic load. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2024-0410/