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Wavelet-based microcrack location method by utilizing nonlinear ultrasonic opposite-side exciting mixing frequency

A non-linear ultrasonic and positioning method technology, which is applied to the analysis of solids using sound waves/ultrasonic waves/infrasonic waves, material analysis using sound waves/ultrasonic waves/infrasonic waves, and measuring devices. It can solve specific locations where micro-cracks cannot exist and give solutions and other issues to achieve good reference, improve utilization, and avoid safety accidents

Inactive Publication Date: 2018-10-26
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although great breakthroughs have been made in the research on metal microcracks, the existing technologies and methods can only give a qualitative judgment on whether there are microcracks in the metal sheet, but cannot give a solution to the specific location of the microcracks.

Method used

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  • Wavelet-based microcrack location method by utilizing nonlinear ultrasonic opposite-side exciting mixing frequency
  • Wavelet-based microcrack location method by utilizing nonlinear ultrasonic opposite-side exciting mixing frequency
  • Wavelet-based microcrack location method by utilizing nonlinear ultrasonic opposite-side exciting mixing frequency

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] A microcrack localization method based on non-linear lamb wave different-side excitation mixing, see figure 1 , the method includes the following steps:

[0046] 101: The first sensor and the second sensor are respectively arranged on both sides of the tested object to form non-linear lamb wave different-side excitation;

[0047] 102: Collect the mixed frequency signal generated by the fatigue crack existing in the tested piece under the action of different side excitation;

[0048] 103: Perform time-frequency analysis on the mixed frequency signal through wavelet transform, extract the characteristic frequency and the time when the characteristic frequency appears, and realize the identification and location of the fatigue damage structure.

[0049] Wherein, the collection in step 102 is specifically:

[0050] First fix the frequency S transmitted by the first RF output port 10, under the premise of matching the frequency responses of the first sensor and the second...

Embodiment 2

[0058] The scheme in this embodiment 1 will be described in further detail below in conjunction with specific drawings and examples, see below for details:

[0059] 201: Build a non-linear lamb wave different-side excitation mixing detection experimental system, collect the mixed-frequency signal generated by the fatigue crack 5 existing in the test piece 14 under the action of different-side excitation, and use it for subsequent processing and analysis;

[0060] Among them, the experimental system such as figure 2 As shown, the detailed operation of the step 201 is:

[0061] 1) Build a nonlinear lamb wave different-side excitation mixing detection experimental system;

[0062] The system includes: a first attenuator 1 and a second attenuator 2 corresponding to the two radio frequency outputs, a low-pass filter structure 3 for processing the two output signals 10 and 11 of the nonlinear ultrasonic instrument 13, and a low-pass filter structure 3 for processing the second Th...

specific Embodiment approach

[0065] The specific implementation is as follows: first fix the frequency S transmitted by the first radio frequency output port 10 10 , under the premise of matching the frequency response of the first sensor 4 and the second sensor 7, set a frequency scanning range (f1, f2) and scanning step size f0, and set the frequency S transmitted by the second RF output port 11 11 According to the range and step size set above, apply the excitation with frequencies f1, f1+f0, f1+2f0, f1+3f0...f2 in sequence, observe and record the best effect of the mixing effect, that is, the amplitude of the mixing signal reaches The corresponding frequency S at the maximum 11 , as the excitation source of the second radio frequency output port 11. According to the nonlinear ultrasonic mixing theory, the frequency of the target feature mixing signal to be extracted is S 10 +S 11 .

[0066] The embodiment of the present invention is described based on the RAM-5000-SNAP nonlinear ultrasonic instrum...

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Abstract

The invention discloses a wavelet-based microcrack location method by utilizing nonlinear ultrasonic opposite-side exciting mixing frequency. The wavelet-based microcrack location method includes: respectively arranging a first sensor and a second sensor on two sides of a to-be-tested piece to form nonlinear opposite-side lamb wave excitation; acquiring a mixing frequency signal generated, by a fatigue crack existing in the to-be-tested piece, under the action of opposite-side excitation; by means of wavelet transformation, subjecting the mixing frequency signal to time-frequency analysis, andextracting characteristic frequency and emerging time of the characteristic frequency to realize recognition and location of a fatigue damage structure. The wavelet-based microcrack location method has the advantages that the wavelet transformation theory and the MATLAB (matrix laboratory) software are combined and applied to a nondestructive testing field, a method for detecting and locating microcracks in metal sheets from a time-frequency analysis angle is provided; by combining excitation with experiment and optimizing parameters continuously, the optimal parameters capable of representing the characteristic frequency of the mixing frequency signal can be acquired, and accuracy and feasibility of a wavelet transformation based nonlinear opposite-side lamb wave exciting mixing frequency locating method are indicated in a result.

Description

technical field [0001] The invention relates to damage location applied in the field of metal non-destructive testing, in particular to a method for realizing micro-crack location by using wavelet transform to analyze non-linear lamb wave mixing detection signals. Background technique [0002] Metal sheets are widely used in military, industrial, medical and aerospace fields. During use, materials will inevitably be affected by external factors such as repeated loads, temperature changes, and corrosion, which will cause fatigue. When fatigue accumulates to a certain extent It will develop into macroscopic cracks, causing safety accidents and major economic losses. [0003] At present, there are four mature methods for non-destructive testing of metals: 1) Ultrasonic flaw detection, which mainly detects metallurgical defects, such as slag inclusions, holes, cracks, etc.; 2) X-ray flaw detection, which detects high-density inclusions in parts, Defects such as tungsten inclusi...

Claims

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Application Information

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IPC IPC(8): G01N29/04
CPCG01N29/041G01N29/048G01N2291/0234
Inventor 李一博王雪王晢马畅曾周末张硕
Owner TIANJIN UNIV
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