On research of incipient gear pitting fault detection using optic fiber sensors

Fiber Bragg grating has been widely used in structural health monitoring due to the following merits: robust to electromagnet interference, multipoint distributed measurements, easy to embed in limited space, and less wire compared with electric strain sensors. In this paper, optic fiber sensors - fiber Bragg gratings (FBGs), were studied for incipient gear pitting fault detection. Different levels of tooth surface wear were simulated and tested in the experimental test rig. The FBG sensors are bonded to the outside of the gearbox directly. It is shown that FBG can effectively reflect the gear meshing frequencies as well as the fault signatures. The diagnostic results indicate that FBG signals can effectively detect wear fault under heavy load conditions. However, the performance of FBGs can be limited by the relatively weak strain signals when the structure stiffness of the gearbox is high. Compared with vibration sensors, FBGs are less sensitive to faults under light load conditions. Vibration signals, on the other hand, are less sensitive to incipient wear fault under heavy load conditions. Therefore, under heavy load conditions, FBG strain sensors can be more suitable for incipient fault detection.