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Natural Fatigue Crack Initiation and Detection in High Quality Spur Gears
ARMY RESEARCH LAB CLEVELAND OH VEHICLE TECHNOLOGY DIRECTORATE
Pagination or Media Count:
There is a desire in the rotorcraft community to transition to an on condition maintenance program. This requires the ability to detect the presence of faults before failure. Gear-tooth root-cracks are of particular concern in the drive system, for they are generally difficult to detect until a crack has progressed to the point where catastrophic failure is eminent. Many diagnostics are developed using experimental data generated from specimens with machined, seeded faults rather than naturally developed cracks. The study presented here develops a methodology for seeding natural tooth root-cracks in gears for use in diagnostic experiments. Fatigue cracks are generated on a load frame and then test gears are run on a rotating fatigue rig instrumented with accelerometers. Data presented shows that by comparing baseline healthy vibration data to cracked gear data, damage can be detected with commonly used condition indicators. However, these indicators were not able to show propagation of the crack because the load capability of the contact fatigue rig was insufficient and propagation did not occur.
APPROVED FOR PUBLIC RELEASE