Method for real-time monitoring of crack on composite-repaired structure based on fiber Bragg grating (FBG) sensor

A composite material and real-time monitoring technology, which is applied in the direction of applying stable tension/pressure to test the strength of materials, analyzing materials, and analyzing materials through optical means to achieve good compatibility, high sensitivity, and high reliability.

Inactive Publication Date: 2018-07-27
CHINA SPECIAL TYPE FLIER RES INST
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Problems solved by technology

Once cracks appear in the repaired structure, if effective monitorin

Method used

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  • Method for real-time monitoring of crack on composite-repaired structure based on fiber Bragg grating (FBG) sensor
  • Method for real-time monitoring of crack on composite-repaired structure based on fiber Bragg grating (FBG) sensor
  • Method for real-time monitoring of crack on composite-repaired structure based on fiber Bragg grating (FBG) sensor

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Embodiment

[0025] The invention is a crack diagnosis method based on the spectral characteristics of the fiber Bragg grating sensor, the process is as follows figure 1 As shown, the specific steps are as follows:

[0026] Step 1: Select the test piece and design the sample piece. Its specification is 350mm*80mm*3mm, and the material is 2A12 aluminum alloy sheet. mm center hole, and prefabricated cracks with a predetermined length of 20mm on both sides of the hole, using wire cutting, such as figure 2 shown;

[0027] Step 2: Carry out structural mechanics analysis on the sample, analyze the stress at both ends of the sample, and perform finite element simulation analysis on the sample to determine the stress distribution of the crack tip area when the crack extends to a specific length; Before the finite element analysis, it is necessary to determine the external loading conditions, such as the type of load, and related parameters such as the material of the sample, elastic modulus, et...

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Abstract

The invention relates to a method for real-time monitoring of a crack on a composite-repaired structure based on a FBG sensor. The method comprises the following steps: step 1, selecting a test piece;step 2, carrying out structural mechanics analysis on the test piece and analyzing stress on two ends of the test piece; step 3, sticking the FBG sensor on an aluminum alloy thin plate (a 2A12 thin plate) according to finite element simulation results; step 4, mounting the aluminum alloy thin plate repaired by a composite and adhered by the FBG sensor on a fatigue testing machine for fatigue crack propagation tests; step 5, analyzing the wavelength changes of the crack after installation of the FBG sensor on the tip of the crack; and step 6, repeating steps 1-5. The method provided by the invention carries out real-time monitoring on the process of crack propagation and is more visual and effective than other methods. The FBG sensor used in the method has the advantages of small size, high sensitivity, electromagnetic interference resistance, corrosion resistance, high reliability, good compatibility with the composite, etc.

Description

technical field [0001] The invention belongs to the technical field of structural health monitoring, and in particular relates to a method for real-time monitoring of cracks in repaired structures of composite materials based on FBG sensors. Background technique [0002] Aluminum alloy materials are widely used in aeronautical structural metal materials. After the cracks in aluminum alloy are repaired with composite materials, the cracks do not disappear. At present, there is still no one to monitor the crack propagation after repairing aluminum alloy damaged structural composite materials. Sophisticated monitoring methods. Once cracks appear in the repaired structure, if effective monitoring cannot be carried out, it will cause extremely serious consequences. [0003] The strain distribution at the crack tip of the repaired composite structure has obvious non-uniform characteristics. When the FBG sensor is subjected to non-uniform strain along its axial length direction, t...

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Application Information

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IPC IPC(8): G01N3/08G01N21/17
CPCG01N3/08G01N21/17G01N2203/0066G01N2203/0641
Inventor 石志想刘元海张辰玉袁猛张莹颖张登朱利敏王浩伟张吉琴陈锐
Owner CHINA SPECIAL TYPE FLIER RES INST
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