The Development Of Multi-channel Fiber Optic Acoustic Emission Testing System

The optical fiber acoustic emission detection technology is a kind of advanced techniques currently used in nondestructive testing field, it has the advantages of high anti-electromagnetism ability and high sensitivity, and it will become a new branch of nondestructive testing technology.Firstly, the acoustic emission generation mechanism and the basic characteristic of sound wave propagating in the solid were introduced in this paper, and then the use of optical fiber sensor for acoustic emission testing were analyzed in theory, and analyzes the phase sensitivity of Sagnac fiber-optic sensor used to detect acoustic emission signal. The common methods about the acoustic emission source location was introduced,the location algorithm in the linearity and the plane and the stereo were derived. Based on this, we designed a multi-channel fiber-optic acoustic emission testing system with DSP for core chip, the system adopts Sagnac fiber-optic sensors as sensing probe, and semiconductor laser provides stable coherent light for the fiber-optic sensors. The system converts the optical signals modulated by the acoustic emission signal into electrical signals when detecting acoustic emission signal, and the signals were amplified by the amplifying filter circuit, then the data acquisition and processing system sample and convert the pre-signals, finally display the time domain waveform and the frequency domain waveform.The test of acoustic emission detection and acoustic emission source location was done using the multi-channel fiber-optic acoustic emission testing system, The self-made simulated sound source was located in the linearity and the plane location experiment using the optical fiber sensor in the steel plate, the results were briefly analyzed, and discussed the influence factors of the optical fiber acoustic emission source location. The results show that the multi-channel fiber-optic acoustic emission testing system can fully used for the acoustic emission signal detection and localization.