Acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG)

Abstract

The invention provides an acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG), which aims to overcome limitation of the prior art and introduce an FBG sensor into the acoustic emission detection field. The acoustic emission signal sensing system comprises a broadband light source, a first fiber coupler, a second fiber coupler, the FBG, a tunable FBG filter, a first photoelectric detection circuit, a second photoelectric detection circuit, an analog-to-digital conversion circuit, an FBG array (FBGA) and a computer. The acoustic emission signal sensing system is mainly applied to structural safety monitoring of an aerospace plane and damage detection of important components, and has the advantages of high sensitivity, high response speed, long transmission distance and strong resistance to electronic interference; and compared with the power-type FBG acoustic emission sensing system, the acoustic emission signal sensing system based on the matching-type FBG provided by the invention has the beneficial effects that wavelength shift information is demodulated by a matching grating method so as to obtain information of an original acoustic emission wave, the detection object is optical wavelength rather than optical power, and optical wavelength information is not affected by optical power loss during the optical transmission process, thus the detection precision is higher, the resolution power is higher and the noise is smaller.

Description

technical field [0001] The invention belongs to the technical field of acoustic emission detection, in particular to an acoustic emission signal sensing system based on a matching fiber Bragg grating. Background technique [0002] Acoustic emission is a new technology that is widely used in modern nondestructive testing and structural material research. Its principle is that the material of the stressed component will release plastic strain energy during the initiation and expansion of damage defects, and the strain energy is in the form of stress waves. Outward propagation expansion, this phenomenon is called the acoustic emission phenomenon. Acoustic emission technology is the use of high-sensitivity acoustic emission sensors installed on the surface of the stressed member to form a certain number of sensor arrays to receive and collect acoustic emission signals from material defects in real time, and then through the identification, judgment and analysis of these acoustic...

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Problems solved by technology

[0004] Existing fiber grating sensing systems, such as Chinese patents ZL201010273400.1 "A Transformer Internal Temperature Detection System Based on Fiber Bragg Grating", ZL200910024155.8 "A Fiber Bragg Grating Stress Monitoring System", etc., all use fiber Bragg grating as a temperature sensor. and stress sensors; the existing acoustic emission detection systems such as Chinese patent CN2724019Y "an earthquake and landslide monitoring system based on acoustic emission" and other acoustic emission detection systems used in the acoustic emission detection system are based on piezoelectric ceramic materials. There is no relatively mature sensor system for detecting acoustic emission signals with fiber gratings

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