Metal plate defect location method based on laser Lamb wave frequency-wave number analysis

A wave frequency, metal plate technology, applied in the field of metal plate defect positioning, can solve the problems of inability to realize multi-frequency defect imaging and single

Active Publication Date: 2017-06-30
BEIJING UNIV OF TECH
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  • Claims
  • Application Information

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Problems solved by technology

Lamb waves with different center frequencies have different sensitivities to defects, but piezoelectric excitation can only excite a single center frequency at a time, and it is not convenient to realize multi-frequency defect imaging

Method used

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  • Metal plate defect location method based on laser Lamb wave frequency-wave number analysis
  • Metal plate defect location method based on laser Lamb wave frequency-wave number analysis
  • Metal plate defect location method based on laser Lamb wave frequency-wave number analysis

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Embodiment Construction

[0040] Provide following experimental examples in conjunction with the content of the inventive method:

[0041] figure 1It is a laser ultrasonic detection system, which is divided into two parts: excitation and reception. The laser ultrasonic excitation part includes a laser controller, a pulse laser, and a laser excitation probe. The laser controller provides energy to the pulsed laser to excite the pulsed laser to generate pulsed laser, which is then emitted by the laser excitation probe. At the same time, the laser controller provides a synchronous trigger signal to the oscilloscope to realize the synchronous excitation and acquisition of laser ultrasonic signals. The laser ultrasonic receiving system includes a continuous pulse laser, a beam splitter, a demodulator, and a laser receiving probe. The continuous pulse laser outputs continuous laser light, which is divided into two beams after passing through the beam splitter. One beam is directly input to the demodulato...

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Abstract

The invention discloses a metal plate defect location method based on laser Lamb wave frequency-wave number analysis and belongs to the field of laser ultrasonic non-destructive testing. The method comprises the following steps: firstly, excitation is performed by a laser excitation probe in a fixed position on a metal plate, a laser receiving probe scans defect lines to receive N groups of Lamb wave data, and a time-space wave field on a scanning path is obtained; secondly, signals under specific center frequency are extracted from the acquired N groups of Lamb wave data with a continuous wavelet transform method, and analyzability of a defect location result is guaranteed; finally, the extracted wave field signals are subjected to space-frequency-wave number imaging with short-space two-dimensional Fourier transform algorithm, and defect location is realized according to characteristics of a wave number spectrum on the scanning path. One completely non-contact type detection method is provided, and action rules between Lamb waves and defects in the wave number field are disclosed.

Description

technical field [0001] The invention provides a metal plate defect location method based on laser Lamb wave frequency-wavenumber analysis, which belongs to the technical field of laser ultrasonic nondestructive testing. Background technique [0002] Plate structure or plate-like structure has a large number of applications in the aviation industry and petrochemical industry. The detection and research of plate structure by non-destructive testing method not only has high scientific research value, but also has important economic and social significance. [0003] Non-destructive testing for large plate structures mainly includes X-ray testing methods, eddy current testing methods, thermal imaging methods, ultrasonic methods and so on. These methods have been widely used in industrial field detection, but inevitably there are some problems. For example, X-rays have radiation effects, and the human body will be seriously injured if exposed to high-intensity rays for a long tim...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/95G01N21/01
CPCG01N21/01G01N21/88G01N21/8851G01N21/95G01N2021/0112G01N2201/06113
Inventor 刘增华冯雪健陈洪磊马春雷何存富吴斌
Owner BEIJING UNIV OF TECH
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