Acoustic emission for the detection of subsurface cracking in bearing condition monitoring

Rolling contact bearing failures are simulated using four-ball machine experiments to generate acoustic emission (AE) signals for a naturally developing fault. Experiments are modified by introducing a weakness to the ball race component in an attempt to reduce test duration. AE is recorded periodically in a customised DAQ system using LabVIEW software. A study of the four-ball geometry and kinematics determines the optimal data sampling parameters and the modulating frequencies associated with faults. Analysis using envelope techniques demonstrates that AE clearly indicates the presence of a subsurface fault approximately 30 seconds before a surface defect develops in the current tests.