Electrotribodynamics of ball bearings in electrical machines

The trend towards electrification presents new challenges in bearing design. One such consideration is the occurrence of electrical discharge contact pathways, which can lead to surface damage. The current study presents a novel comprehensive multiphysics model, incorporating bearing dynamics, mechanics of lubricated rolling element-to-races contacts and electrical contact model for both DC and AC voltages. The model also includes both electrical resistance and capacitance effects in the bearing contacts. Key bearing vibration frequencies such as cage frequency and the bearing base natural frequency along with the voltage supply frequency are observed as influential in the electric current discharge. The developed model enables the prediction of rhythmic fluting patterns commonly observed in the failed bearing applications subject to electrical discharge.