Method for detecting peripheral defect of hollow cylinder by ultrasonic frequency dispersion compensation principle

A hollow cylinder, dispersion compensation technology, applied in the direction of processing the response signal of the detection, can solve the problems of difficulty and loss of detection range, etc.

Active Publication Date: 2016-02-03
ZHEJIANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But this requires a completely symmetrical excitation of the T(0,1) mode on the pipe, which is difficult to achieve in practice
In addition, increasing the resolution of detecting defects often requires a higher center frequency, which, however, results in a loss of effective detection range

Method used

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  • Method for detecting peripheral defect of hollow cylinder by ultrasonic frequency dispersion compensation principle
  • Method for detecting peripheral defect of hollow cylinder by ultrasonic frequency dispersion compensation principle
  • Method for detecting peripheral defect of hollow cylinder by ultrasonic frequency dispersion compensation principle

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Embodiment

[0065] A certain 304 stainless steel pipe is detected by the above method. The length of the pipe is 1500mm, the outer diameter is 101mm, and the wall thickness is 1mm. A magnetostrictive material 8 with a thickness of 0.1mm and a width of 10mm is pasted on one end of the pipe. The magnetostrictive material 8 is iron cobalt-vanadium alloy, and the excitation coil 5 is surrounded by the magnetostrictive material 8. Then between the circumferential defect 7 and the excitation coil 5, the magnetostrictive material 8 is also affixed at the place where the distance from the excitation coil 5 is 322 mm; then the magnetic field excitation controller 1 is controlled to transmit a voltage pulse signal to the excitation coil 5, and the receiving coil 6 The reference signal s transmitted from the excitation coil 5 for the first time is successively received respectively ref (θ, t) and the echo signal s reflected from the circumferential defect 7 obj (θ, t), data is collected every 11°15...

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Abstract

The invention discloses a method for detecting the peripheral defect of a hollow cylinder by an ultrasonic frequency dispersion compensation principle. The method comprises the following steps of (1) stimulating out ultrasonic guide waves in the hollow cylinder, and using a guide wave receiver for respectively obtaining a reference signal s<ref>(theta,t) and a peripheral defect echo signal s<obj>(theta,t); (2) calculating the peripheral defect position according to the time differences and the sound speed of the two signals; (3) performing two-dimensional Fourier transform on the s<ref>(theta,t) and the s<obj>(theta,t), exerting the phase shifting, and performing the one-dimension Fourier conversion relevant to the (n-theta) transform pair to obtain the distributions shown as the accompanying drawing on a (theta, omega) domain; (4) using the first distribution shown as the accompanying drawing as the reference for performing Wiener filtering on the second distribution shown as the accompanying drawing; (5) calculating the distribution A(theta) of the amplitude value s<dec> (theta,t) along the hollow cylinder peripheral rotating angle theta and the half height width of the distribution A(theta), i.e., the peripheral dimension of the defect of the hollow cylinder. The method has the advantages that the measurement on the position and the dimension of the peripheral defect of the hollow cylinder is realized; higher precision is realized.

Description

technical field [0001] The invention relates to the non-destructive detection of the circumferential defect of the hollow cylinder, in particular to a method for detecting the position and size of the circumferential defect of the hollow cylinder by using a guided wave dispersion compensation algorithm. Background technique [0002] Nowadays, pipelines are used more and more in the transportation industry, and pipeline accidents also increase accordingly, which has brought huge losses to the national economy and threatened people's lives. Therefore, it is particularly important to carry out economical, applicable, simple and effective non-destructive testing on pipelines. The technology of non-destructive detection of pipeline defects using ultrasonic guided wave technology has also attracted more and more attention. [0003] In the existing research, Gazis et al. gave the calculation expression of hollow cylinder dynamic analysis under the assumption of linear isotropic el...

Claims

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Application Information

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IPC IPC(8): G01N29/44
Inventor 居冰峰王传勇孙泽青杜慧林孙安玉
Owner ZHEJIANG UNIV
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