Multi-crack damage identification apparatus and method for cantilever flexible beam

Abstract

The invention discloses a multi-crack damage identification apparatus and method for a cantilever flexible beam. The apparatus comprises a flexible beam, a mechanical clamping device, a detection device, a vibration exciter, a signal generator, a power amplifier, a fiber Bragg grating demodulator and a computer. One end of the flexible beam with multiple cracks is fixed through the mechanical clamping device; a multi-channel FBG optical fiber sensor group is adhered on the flexible beam and is evenly distributed along the length direction of the flexible beam; a signal generated by the signal generator is amplified by the power amplifier and then enters the vibration exciter; the vibration exciter excites low-order mode vibration of the flexible beam; the vibration results in curvature changes at measurement points of each sensor of the beam; the sensors input the curvature changes into the fiber Bragg grating demodulator in the form of wavelength changes; a demodulated signal enters the computer for modal analysis of the flexible beam, drafting of a modal curvature curve, calculation of damage indexes and establishment of a wavelet neural network identification model; and finally, the purpose of accurate identification of the depth and the location of the cracks of the flexible beam is achieved.

Description

technical field [0001] The invention relates to the field of damage identification of large flexible structures, in particular to a multi-crack damage identification device and method for a cantilever flexible beam. Background technique [0002] Due to impacts, earthquakes, wind loads, corrosion, etc., the internal structure of the material will change during the service period of the space flexible structure, resulting in various damages. For large structures, damage threatens the safety of people's lives and properties all the time. Therefore, it is particularly important to detect damage in time and repair it. Early damage identification technology used ultrasonic, X-ray, electromagnetic wave and other means to detect damage. Since the approximate location of the damage needs to be known in advance and the damaged part is required to be easily accessible, it is limited in practical engineering applications. According to the different structural responses, modern damage ...

AI Technical Summary

Problems solved by technology

However, for the identification method based on modal curvature, in actual engineering applications, the measurement accuracy has a significant impact on the results, and it is often required that the location of the measurement points is relatively close and the number of measurement points is relatively large. Otherwise, based on the modal curvature interpolation of the measurement points The estimated curve will introduce a large error

In addition, it is difficult to obtain high-order mode shapes in engineering applications. In traditional low-amplitude vibration tests, the magnitude of modal curvature changes is too small to play an effective role in discrimination.

These shortcomings make this method unsuitable for large and complex projects

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