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Method for non-contact wave velocity extraction of Rayleigh wave of anisotropic blocky material

A wave velocity extraction, non-contact technology, applied in the detection of response signals, etc., to achieve the effect of avoiding random errors

Active Publication Date: 2012-07-04
BEIJING UNIV OF TECH
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  • Abstract
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Problems solved by technology

[0005] The purpose of the present invention is to solve the problem of extracting the Rayleigh wave broadband continuous wave velocity of isotropic bulk materials, and propose an advanced material wave velocity extraction method

Method used

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  • Method for non-contact wave velocity extraction of Rayleigh wave of anisotropic blocky material
  • Method for non-contact wave velocity extraction of Rayleigh wave of anisotropic blocky material
  • Method for non-contact wave velocity extraction of Rayleigh wave of anisotropic blocky material

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Embodiment Construction

[0039] The content of the present invention will be further described in detail below in conjunction with specific examples:

[0040] Step 1): Establish the formula for wave velocity extraction.

[0041] In the case of single frequency excitation / reception, figure 2 In the schematic diagram of leakage surface wave propagation shown, the propagation time of the direct reflection echo I on the upper surface and the propagation time of the leakage surface wave L are respectively:

[0042] t 1 = 2 ( R - Vz ) v w - - - ( 1 )

[0043] t 2 = 2 ( R - Vz cos θ SAW ) v w + 2 · Vz · tan θ SAW v SAW - - - ( 2 )

[0044] Where R is the focus radius, Vz is the defocus distance, v w Is the ultrasonic wave speed of water, θ SAW To generate the Rayleigh angle of the surface wave, v SAW Is the surface wave velocity of the material. So the time difference between ...

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Abstract

The invention discloses a method for the non-contact wave velocity extraction of a Rayleigh wave of an anisotropic blocky material, and the method belongs to the technical field of nondestructive examination. In the nondestructive examination for mainly measuring the wave velocity of an acoustic wave, a V(z) curve formed by the interference of a leaky surface wave and a directly reflected wave, namely a longitudinal wave, comprises much information at the microstructure aspect of the material; the method is based on a defocusing measurement system; a wide-frequency pulse is utilized as an excitation source; an ultrasonic wave comprising a plurality of frequency components is received; and the V(z) curve of the material and an oscillating period thereof are obtained through an improved two-dimensional Fourier transform technique, so as to achieve the extraction of the wave velocity of the Lamb wave of the blocky material. By using the method, the wave velocities of the Rayleigh waves of different materials can be extracted; the wave velocity of the Rayleigh wave can be extracted in a wide frequency scope; a single-frequency point-by-point way is replaced; the wave velocities of the Rayleigh waves in different frequency ranges can be extracted; an averaged value is selected as the wave velocity of the Rayleigh wave of the material; and the random error caused by an accidental factor in a single-frequency extraction process is avoided.

Description

Technical field [0001] The invention belongs to the field of non-destructive testing, and specifically relates to a method for extracting the wave velocity of the Rayleigh wave of isotropic bulk materials. Background technique [0002] With the continuous development of materials science, various functional materials continue to emerge, but due to the influence of the preparation process, the geometric dimensions of many new materials are very limited, such as metallic glass and bulk nanomaterials. Therefore, the use of destructive traditional mechanical performance testing methods such as tension will not meet the needs of new materials. In the non-destructive testing, which mainly measures the acoustic wave velocity, the V(z) curve formed by the interference of the leaky surface wave and the direct reflected wave contains a lot of information on the microstructure of the material. Using an ultrasound microscope as a wave velocity measurement tool can be It is used to detect th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/36
Inventor 何存富吕炎宋国荣柳艳丽高忠阳吴斌
Owner BEIJING UNIV OF TECH
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