Detecting method and sensor for cracks of civil structure based on optical fiber long chirped grating frequency domain reflection technology

A technology of chirped grating and frequency domain reflection, which is applied in the direction of transmitting sensing components, instruments, measuring devices, etc. by using optical devices, can solve the problem of failure of strain gauge sensors, insufficient accurate detection of structural cracks and accurate position information, and inability to obtain overall Information and other issues, to achieve the effect of high spatial positioning accuracy, high cost performance, and good system stability

Active Publication Date: 2012-10-24
SOUTHEAST UNIV
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Problems solved by technology

However, research and engineering practice have shown that due to local stress concentration and cracks in the structure, the strain gauge sensor will fail
The fiber optic FBG sensor can only measure the strain distribution of a series of discrete points, but cannot obtain the overall information
The spatial resolution of the Brillouin scattering optical fiber sensor can only reach tens of centimeters at most, which is not enough to accurately detect structural cracks and accurate position information

Method used

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  • Detecting method and sensor for cracks of civil structure based on optical fiber long chirped grating frequency domain reflection technology
  • Detecting method and sensor for cracks of civil structure based on optical fiber long chirped grating frequency domain reflection technology

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specific Embodiment approach 1

[0012] Specific implementation mode one: the following combination figure 1 , 2 This embodiment will be specifically described. The tunable laser 1 emits a narrow linewidth laser whose wavelength changes with time, enters the coupler 2 and is divided into two paths. One path of light is used as a reference light and passes through the polarization controller 5 and the coupler 4 before entering the photodetector 7, and the other path is used as a transmission path. The photosensitive light enters the long chirped grating sensor 6 through the coupler 3 and is reflected by the grating. The reflected light passes through coupler 3 into coupler 4 and then into photodetector 7 . The current signal output by the optical signal after passing through the photodetector 7 is collected by the data acquisition card 8, and then the signal is analyzed by the signal processing part 9 to obtain the change of the reflected light signal of the optical fiber long chirped grating contained in th...

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Abstract

The invention discloses a detecting method and a sensor for cracks of a civil structure based on an optical fiber long chirped grating frequency domain reflection technology. In the detecting method, a distributed optical fiber monitoring system is formed on the basis of the frequency domain analysis technology of optical fiber long chirped grating so as to realize the strain monitoring and crackpositioning of a structure. Compared with the prior art, the invention has the advantages that spatial resolution is high, micrometer-grade spatial resolution can be realized, and the spatial positioning accuracy is high; the distributed detection of tiny cracks and damages of materials can be realized; the sensitivity is high, the system stability is good; in addition, the sensor has simple structure, low cost and high cost performance.

Description

technical field [0001] The invention relates to a frequency domain analysis technology distributed optical fiber monitoring system based on optical fiber long chirped grating and an implementation method thereof, which can realize strain monitoring and crack positioning of structures. Background technique [0002] Structural health monitoring is to obtain the internal information of the structure through various non-destructive testing methods, and make safety evaluation and necessary early warning. The sensors currently used for structural health monitoring mainly include strain gauges, fiber Bragg grating (FBG) sensors, and distributed fiber optic sensors based on Brillouin scattering. However, the research and engineering practice show that due to the local stress concentration and cracks in the structure, the strain gauge sensor will fail. The fiber optic FBG sensor can only measure the strain distribution of a series of discrete points, but cannot obtain the overall in...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/16G01D5/26
Inventor 孙安吴智深
Owner SOUTHEAST UNIV
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