Laser Acoustic Sensor for Gearbox Vibration Monitoring and Diagnostics

When rotating machinery deteriorates, vibration patterns change. The key is knowing where and how deeply to look. Gear mesh frequencies change in amplitude and the slimness or "All of their peaks change, indicating wear. Weakened teeth, due to root cracking or other gear damage,cause detectable changes. There have been problems -- until now -- using these phenomena for detailed assessment of machinery like high-performance aircraft gearboxes. An artificial "noise floor" and the sensor limitations of accelerometer technologies have caused this. Epoch Engineering, Inc. (EEI) has developed and has demonstrated a unique acoustic detection ability. Our Robust Laser Interferometer is able to detect and display frequencies from below 1 Hz to 100 KHz at amplitude differences up to 11 orders of magnitude (110 dB). The unique capability, when compared to customary accelerometer field implementations, allows measurements not previously practical (effectively dropping the noise floor in spite of the presence of high amplitude vibrations). This process allows us to interrogate the outside of such a machine as a gearbox and detect signals originating inside. It can "baseline" a gearbox on the test stand and then monitor its performance on wing and serve as the fundamental sensing technology for automated systems of machinery monitoring.