Calculation Method for Separation of Bending Mode Reflection Signals Based on Ultrasonic Guided Waves

A technology of bending mode and ultrasonic guided wave, which is applied in the direction of processing the response signal of detection, etc., to achieve the effect of high accuracy of results, saving manpower, and easy implementation

Active Publication Date: 2017-08-25
BEIJING UNIV OF TECH
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Problems solved by technology

However, the current ultrasonic guided wave testing technology often only considers the reflected and transmitted non-bending mode guided waves, and pays little attention to the bending mode generated by mode conversion, and the bending mode signal contains rich defect information, so the symmetrical mode is separated It is of great significance to promote the ultrasonic guided wave detection technology with the bending mode signal

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  • Calculation Method for Separation of Bending Mode Reflection Signals Based on Ultrasonic Guided Waves
  • Calculation Method for Separation of Bending Mode Reflection Signals Based on Ultrasonic Guided Waves
  • Calculation Method for Separation of Bending Mode Reflection Signals Based on Ultrasonic Guided Waves

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Embodiment Construction

[0033] In conjunction with the content of the method of the present invention, the calculation method example of the following double-hole defect T (0, 1) mode and bending mode reflection coefficient in the pipe is provided, and the specific steps are as follows: figure 1 Shown:

[0034] 1) Build as figure 2 The three-dimensional pipeline model shown has a model length of 3000mm, an outer diameter of 76.2mm, a wall thickness of 5.5mm, a ratio of diameter to thickness of 13.85, and a density of 7843kg / m 3 , Young's modulus is 210GPa, Poisson's ratio is 0.28; 90 excitation nodes are set on the outer ring of the pipe end; at a distance of 2000mm from the signal excitation end, circular hole defects distributed in the circumferential direction are set, and the diameter of the circular hole is 5.5mm, the angle between the centers of the two circular holes must be greater than 10 degrees; the distance between the signal monitoring surface and the defect center is 1000mm, and 90 equ...

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Abstract

The invention discloses a calculation method for separating symmetrical and bending mode wave packets and extracting weak bending mode signals. The invention is based on the wave structure characteristic theory of axisymmetric mode and bending mode, and uses finite element software to establish related models. Extract the transient displacement signal of the signal acquisition node on the guided wave monitoring surface, delay and superimpose the collected signal in the frequency domain according to the relevant formula; then perform inverse Fourier transform on the superimposed frequency domain signal to obtain the separation After the guided wave modal wave envelope of each order, the reflection coefficient of each mode is obtained by using the Hilbert yellow envelope. Use the secondary development function of finite element software to write the secondary development program, and quantitatively analyze the impact of detection parameters such as defect size characteristics, position distribution, defect number, and center excitation frequency on the bending mode reflected from the defect through mode conversion. Therefore, the reflection coefficient of the axisymmetric mode and the bending mode is comprehensively used to evaluate the defect position distribution.

Description

technical field [0001] The invention relates to a calculation method for quantitative analysis of the action mechanism of ultrasonic guided waves propagating in a tubular waveguide and defects, especially using the wave structure characteristics of axisymmetric mode and bending mode to separate symmetrical and bending mode wave packets and extract bending For weak modal signals, the reflection coefficients of each mode are obtained by using the Hilbert yellow envelope, and the reflection coefficients of the axisymmetric mode and the bending mode are comprehensively used to evaluate the defect position distribution Background technique [0002] Thick-walled pipe refers to a tubular steel structure with a ratio of outer diameter to wall thickness of less than 20. Thick-walled pipes are widely used in the fields of petroleum, chemical industry, and thermal power generation. Since the pipes work in high-temperature and high-pressure environments and the inner and outer walls of ...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N29/44
Inventor 郑明方何存富吴斌吕炎丁俊才
Owner BEIJING UNIV OF TECH
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