Early Weak Fault Diagnosis of Rolling Bearings Based on Fiber Bragg Grating Sensing Monitoring

Abstract

Aiming at the problems of weak dynamic response and difficulty in diagnosis of early damage of rolling bearings, a diagnosis method for early damage of rolling bearings is proposed. Taking radial rolling bearings as the main research object, the load symmetric structure of deep groove ball bearings is analyzed. Based on the mechanical second-order system theory, the sensor monitoring structure is constructed. The generalized resonance principle is used to identify weak signals, and the fiber Bragg grating is used for signal sensing. The signal is obtained through the fiber Bragg grating high-speed demodulator. When a continuous periodic generalized resonance wave appears in the amplitude–frequency analysis of the signal, and there is a high-frequency resonance frequency, it can be proved that the bearing is faulty. The diagnosis method can effectively avoid the interference of low-frequency signals, the frequency spectrum is pure and there is no electromagnetic interference. It fully shows that the fiber Bragg grating sensor is suitable for the monitoring and diagnosis of the early weak fault of the bearing.

Repeatability of FBG-based damage detection on bearings

“…From this figure, a similar trend as in Figure 4 can be observed: the amplitude of the strain signal at the BPFO is also affected by the installation of bearing and fiber and will therefore influence the use of these features for further damage detection. Typically, the sum of the amplitudes at several higher harmonics of the BPFO is used as a damage feature [1][2][3][4][5] .…”

“…In order to investigate the repeatability of the fault detection methodology proposed in literature [1][2][3][4][5] for measurements with sensors installed directly on the bearing, we performed two repeatability experiments. First, we used one healthy bearing and one faulty bearing and installed them in the rotating setup 5 times, measuring the strain signals in the same conditions, and second, we used one healthy bearing and one faulty bearing and sequentially installed 5 optical fibers sensors on each bearing and performing strain measurements in the same conditions after removing the previous fiber.…”

“…Although OFS have been demonstrated to be able to detect bearing faults, this has mostly been done by placing the fibers on the bearing housing [1][2][3][4][5] . The bearing faults that have been studied are typically also quite large (>2 mm) and therefore not representative of early damage 1,2 .…”