Development of an accelerated degradation testbed for integrated vibration monitoring and online oil analysis of vehicle differential bearings

This project, sponsored by the Office of Naval Research, integrates oil and vibration analysis to develop a more complete diagnostic and prognostic model for monitoring bearing degradation and performance in the field. The results of this project will be used to optimize repair schedules and minimize the risk of catastrophic failure of machine components for military personnel during a mission through enhanced condition-based maintenance. Each test bearing is first introduced with an outer race fault. The fault's degradation is accelerated by running the bearing under overloaded conditions in the boundary lubrication regime within a large test rig designed for these conditions. Accumulated damage to the bearing is characterized in another clean, low-noise test rig to collect vibration signatures. Finally, the bearing is implemented into the differential for in-situ testing to emulate data in the field. Dynamic characterization of the designed test machines was performed by long runs spanning multiple hours under rated conditions to determine any wear-in effects and ramp-up tests to distinguish order-based bearing frequencies and structural resonances. Modal analyses were performed on the static system to provide additional evidence of structural resonances within the machines. This paper will discuss the design challenges and solutions for creating a test bed to monitor bearings in accelerated-degradation conditions and in realistic operating conditions.