Crack damage monitoring and strain field measuring method based on FBG (Fiber Bragg Grating) sensor array spectrum

Abstract

The invention discloses a crack damage monitoring and strain field measuring method based on an FBG (Fiber Bragg Grating) sensor array spectrum. The method comprises the following steps: 1, selectinga test specimen to be measured; 2, performing structural mechanics analysis on the test specimen to be measured; 3, sticking a sensor to the test specimen; 4, performing a loading experiment on the test specimen stuck with the FBG sensor to determine an experimental system; 5, performing analysis on a series of obtained spectra to explore the corresponding relation between the characteristic parameters of the spectra and the initial positions of cracks as well as the extension conditions of the cracks; and 6, comparing the stress strain and the distance curve obtained by the FBG sensor with finite element simulation results. By virtue of the steps, crack damage monitoring and crack tip stress field measurement are realized, the corresponding relation between crack damages and spectra is achieved, and the feasibility of the method for measuring the crack tip strain field can be verified through experiments.

Description

technical field [0001] The invention relates to the field of structural health monitoring, in particular to a method for crack damage monitoring and strain field measurement based on FBG sensor array spectrum. Background technique [0002] In recent years, with the rapid development of industry, large-scale equipment and structures, increased design stress levels, and high-strength aluminum alloys have been put into use, many vicious fracture accidents have occurred one after another. After various studies, it is believed that these fractures all originate from the poor toughness and low hardness of aluminum, and the material is prone to cracks. However, the traditional design thought that the material is a continuous, uniform and isotropic medium, and has never considered the defects in the material. Obviously, this is inconsistent with the actual engineering. In order to ensure the safety of the structure and prevent the occurrence of fracture accidents, people began to ...

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Problems solved by technology

[0003] In the relevant literature and experiments, it is found that the crack position and expansion of the aluminum alloy crack damage are currently based on the wavelength drift of the FBG sensor, but when the strain field caused by the damage causes the FBG to split the peak, this cannot pass the wavelength drift at this time. to obtain damage information, and the relevant literature does not involve the measurement of the stress field at the crack tip

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