Online Diagnosis of Small Faults in Rolling Bearings Using FBG Acoustic Emission Sensors Inside the Accelerated Life Tester

Abstract

Rolling bearings are widely used in many industries and their online diagnosis is very important. However, there is still no effective way to detect small faults online. In this article, a fiber Bragg grating (FBG) acoustic emission (AE) sensing method is proposed and tested inside an accelerated bearing life tester (ABLT). The FBGAE sensors are small, resistant to electromagnetic interference, intrinsically explosion-proof, and are thus fit for the inner environment of an ABLT, which is small, has high electromagnetic interference, and is full of lubrication oil. Therefore, we could install the FBG AE sensors inside an ABLT. The experimental system based on the principle of tunable narrowband laser demodulation is built up to collect the AE signals of faulty rolling bearings with different fault types. Then, with the envelope demodulation algorithm, we obtained the fault characteristic frequencies of the bearings that were consistent with the theoretical fault frequencies. The results show that the FBG AE sensors are sensitive to the small faults of rolling bearings and can be used inside an ABLT.