Planetary Gearbox Fault Diagnosis Using a Single Piezoelectric Strain Sensor

Planetary gearboxes are widely used in the drivetrain of helicopters and wind turbines. Any planetary gearbox failure could lead to breakdown of the whole drivetrain and major loss of helicopters and wind turbines. Therefore, planetary gearbox fault diagnosis is an important topic in prognostics and health management (PHM). Planetary gearbox fault diagnosis has been done mostly through vibration analysis over the past years. Vibration signals theoretically have the amplitude modulation effect caused by time variant vibration transfer paths due to the rotation of planet carrier and sun gear, and therefore their spectral structure is complex. It is difficult to diagnose planetary gearbox faults via vibration analysis. Strain sensor signals on the other hand have less amplitude modulation effect. Thus, it is potentially easy and effective to diagnose planetary gearbox faults via stain sensor signal analysis. In this paper, a research investigation on planetary gearbox fault diagnosis via strain sensor signal analysis is reported. The investigation involves using time synchronous average technique to process signals acquired from a single piezoelectric strain sensor mounted on the housing of a planetary gearbox and extracting condition indicators for fault diagnosis. The reported investigation includes analysis results on a set of seeded fault tests performed on a planetary gearbox test rig in a laboratory. The results have showed a satisfactory planetary gearbox fault diagnostic performance using strain sensor signal analysis.