Acoustic emission signal sensing system based on fiber Bragg grating

Abstract

The invention provides an acoustic emission signal sensing system based on fiber Bragg grating (FBG). The system comprises a fiber grating sensing unit and a signal processing unit; the fiber grating sensing unit comprises an FBG sensor, a light source, an isolator and a Y-type fiber coupler; the signal processing unit comprises a photoelectric switching circuit, an amplification circuit, a filter circuit, an A/D circuit and an FPGA (field-programmable gate array); the FBG sensor is firmly fixed in a packaging material, and a couplant is added between the packaged FBG sensor and a member to be detected. The system provided in the invention has the following advantages: a wide detection frequency band, detection scope being in a range of 50 KHz to 300 KHz; high sensitivity, strain resolution being 2 (mu epsilon) microstrani; a fast response speed more than 10 MHz; a long transmission distance which enables long distance between a detection spot and a monitoring spot to be feasible thanks to low loss transmission of fibers; strong capability in resisting electromagnetic interference, vibration, dampness, corrosion, etc., which enables the system to be used normally for a long time in a severe environment. A sensor made of fibers in the invention has the advantages of light weight, small volume, good imbedibility, etc.

Description

technical field [0001] The invention relates to an acoustic emission signal sensing system based on a fiber Bragg grating, and belongs to the technical field of acoustic emission detection. Background technique [0002] As the embodiment of the country's comprehensive strength and military strength, aviation aircraft plays an increasingly important role in modern warfare. It plays an increasingly important role in early warning, reconnaissance, anti-tank, air defense, electronic warfare, and air command systems. Aircraft has become the most important weapon for gaining the initiative in war, and will have an important and even decisive impact on the course and outcome of the war. However, because the structure of the aircraft is very precise and complex, it often works in various harsh environments, as well as flying at hypersonic speeds, etc., resulting in an increased probability of failure, such as cracks in parts, corrosion, structural fractures, etc., these The process...

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Problems solved by technology

Existing acoustic emission detection systems such as Chinese patents CN101561420A "intelligent acoustic emission continuous monitor", CN101446507 "USB2.0 multi-channel acoustic emission detection system", CN2724019 "an earthquake and landslide monitoring system based on acoustic emission", etc. The acoustic emission sensors used in the acoustic emission detection system are all based on piezoelectric ceramic materials, which have large volume, narrow frequency band, poor anti-vibration ability, short transmiss...

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