Hole-edge crack diagnosis method based on optical fiber spectrum image analysis

Abstract

A hole-edge crack diagnosis method based on optical fiber spectrum image analysis includes the following steps: (1) selecting a test sample and designing the test sample; (2) performing structural mechanics analysis to the test sample; (3) pasting fiber Bragg grating sensors on an aluminum alloy thin board; (4) according to finite element simulation results, backstepping the principle of a reflective spectrum image of the FBG sensors; (5) installing the aluminum alloy thin board, on which the FBG sensors are pasted, on a fatigue test machine to perform fatigue crack propagation test; (6) processing signals collected by the FBG sensors; and (7) repeating the steps (1) - (5) to verify the method established in the step (6); and (8) completing real-time monitoring of the cracks. By means of the steps, the hole-edge crack diagnosis method based on transversal-arranged FBG spectrum analysis is achieved, thereby achieving the researching effect of diagnosis on length of a hole-edge crack. The method solves the positioning problem of length of the hole-edge crack in the aluminum alloy board in engineering application.

Description

technical field [0001] The invention provides a hole edge crack diagnosis method based on optical fiber spectral image analysis, which is applied to the fatigue crack monitoring problem of metal plates, and specifically relates to a method for monitoring the fatigue crack growth of aluminum alloy thin plates by using the spectral characteristics of optical fiber grating sensors , which belongs to the field of structural health monitoring. Background technique [0002] Structural health monitoring is a technology that uses advanced smart sensors to monitor the health of structures in real time. Compared with traditional non-destructive testing technology, it is more efficient and more targeted, so it is widely used in the aerospace field. Fatigue cracks are a typical damage of metal structures, if effective monitoring cannot be carried out in the initial stage of crack initiation and propagation process, it will cause serious consequences. At present, using structural health...

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Problems solved by technology

[0003] In the relevant literature and experiments, it is found that for the qualitative problem of the presence or absence of cracks in the process of crack propagation at the edge of the aluminum alloy plate hole, the smart coating sensor will have missed detection and false alarms during monitoring, and the fiber grating sensors currently used are mostly Establish the relationship between strain and crack length, and the extracted characteristic parameters are mostly statistical models without physical meaning, and do not explain the relationship between crack growth and reflection spectrum from the perspective of optical properties itself

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