Supersonic guide-wave time reversion detection apparatus and method for defect of pipeline

A time-reversal, ultrasonic guided wave technology, used in pipeline systems, mechanical equipment, gas/liquid distribution and storage, etc., can solve problems such as limiting the flexibility of guided wave detection methods, difficulty in waveform identification, and difficulty in small defect identification.

Active Publication Date: 2007-06-13
BEIJING UNIV OF TECH
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Problems solved by technology

[0006] Since the device has only one signal excitation channel, it determines that only the same signal can be excited by one or more sensor units at the same time, this excitation method greatly limits the flexibility of the guided wave detection method
[0007] Existing guided wave detection methods usually use guided waves that excite approximately a single mode for defect detection, but due to the multi-mode characteristics of guided waves, the mode conversion phenomenon that occurs at the defect will also disperse the energy, making each The amplitude of the wave packets of modal defects is relatively small, which makes it difficult to identify small defects
If the detection energy is simply increased by increasing the number of cycles of the excitation signal, the reflected echo packet will be extended in time due to the dispersion phenomenon, which will cause difficulties in waveform identification
So far, no relevant literature has proposed a better solution to this problem.

Method used

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  • Supersonic guide-wave time reversion detection apparatus and method for defect of pipeline
  • Supersonic guide-wave time reversion detection apparatus and method for defect of pipeline
  • Supersonic guide-wave time reversion detection apparatus and method for defect of pipeline

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Embodiment 1

[0056] As shown in Figure 3, the pipeline simulated in this numerical experiment example is a steel pipe with a length of 1.8m, an outer diameter of 70mm, and a wall thickness of 3.5mm. The density is 7932kg / m 3 , the longitudinal wave velocity is 5960m / s, and the transverse wave velocity is 3260m / s.

[0057] Taking the detection process of an oblique crack defect with a length of 35mm, a width of 2mm, and an angle of 45° with the axial direction of the pipeline at a distance of 720mm from the excitation end of the pipeline as an example, the description is as follows.

[0058] 1) Calculate the group velocity dispersion curve according to the pipeline parameters, as shown in Figure 5. Select 140kHz as the excitation frequency, and simulate the 48-channel guided wave multi-channel excitation / receiving device 7 by simultaneously loading 5 periods of sinusoidal axial displacement loads plus the Hanning window on 48 nodes at the end of the pipeline near the defect, and The longi...

Embodiment 2

[0067]Embodiment 2 still detects the penetrating oblique crack defect at a distance of 720 mm from the excitation end of the pipeline, with an inclination angle of 45 degrees, a length of 35 mm, and a width of 2 mm. The detection method and steps are exactly the same as those in Embodiment 1, except that the window width T of the signal intercepting rectangular window is different. The window width T in this embodiment ensures that the rectangular window can intercept defect echo information of at least one mode. For the generation of the time-reversed excitation signal, T=0.06 ms is selected according to FIG. 6( a ). And the rectangular window starts to intercept the defect reflection echo signals in the signals received by 48 nodes from the same time starting point of 0.27 ms. Using such a time-reversal excitation signal to obtain the final time-reversal detection signal is shown in Fig. 6(e).

[0068] It can be seen from Embodiment 1 and Embodiment 2 that the time-reversal...

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Abstract

The invention relates to pipeline defect ultrasound guided wave time reversal detection device and method. The method includes the following steps: selecting detecting frequency according to the detected pipeline corresponding free hollow column structure group velocity dispersion curve; inputting the frequency into the arbitrary function generator to generate center frequency used as single sound signal; sending the signal to each passage of exciting/receiving set to transducer unit; exciting longitudinal axis symmetry guided wave modal; sending the reflected signal to the computer and gaining reversal excitation signal by time reversal; repeatedly exciting guided signal to detect. The invention realize space and time focus for guided wave detection, greatly improve detection capability for little defect.

Description

technical field [0001] The invention relates to an ultrasonic guided wave time-reversal detection device and method for pipeline defects, belonging to the field of non-destructive testing. Background technique [0002] As an important part of production systems, transportation and manufacturing equipment, pipelines play an irreplaceable role in industries such as machinery, petroleum, chemical, food and urban water supply. However, after the pipeline has been in service for a long time, pipeline leakage due to corrosion, wear, accidental damage and other reasons occurs from time to time, causing great losses to the country and the people. Therefore, it is imminent to vigorously develop pipeline detection technology. [0003] Ultrasonic guided wave has the characteristics of small attenuation along the propagation path and long propagation distance. The detection signal can also contain the overall information from the excitation point to the receiving point. It is very suit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F17D5/06
Inventor 吴斌邓菲何存富
Owner BEIJING UNIV OF TECH
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