Nonlinear wave detection method for high-cycle fatigue damage of metal sheet

A metal thin plate, high-cycle fatigue technology, applied in the use of sound waves/ultrasonic waves/infrasonic waves to analyze solids, use sound waves/ultrasonic waves/infrasonic waves for material analysis, and measurement devices, etc., can solve insensitivity and other problems, and achieve the effect of improving accuracy

Pending Publication Date: 2021-08-31
ZHEJIANG UNIV OF TECH
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Problems solved by technology

Although the nondestructive testing technology included in the linear ultrasonic testing technique is ideal for detecting macroscopic defects in materials...

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  • Nonlinear wave detection method for high-cycle fatigue damage of metal sheet
  • Nonlinear wave detection method for high-cycle fatigue damage of metal sheet
  • Nonlinear wave detection method for high-cycle fatigue damage of metal sheet

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Embodiment 1

[0081] A nonlinear wave detection method for high cycle fatigue damage of metal sheets, the specific steps are as follows:

[0082] S1: First use Matlab to solve the Rayleigh-Lamb equation, and draw the dispersion curves of the phase velocity and group velocity of the high-strength steel FV520B plate specimen.

[0083] S101: The expression of the Rayleigh-Lamb equation is as follows:

[0084] symmetrical mode; Anti-symmetric mode where, Wave number:

[0085] Angular frequency: w=2πf, d is the thickness, f is the frequency, c P is the phase velocity.

[0086] S102: Finally, the above equation can be regarded as g(f,c p )=0, it will be found that for a given plate structure, there will be c in the equation p and f two unknown parameters, usually we can not calculate the exact analytical solution according to the above equation. Through the idea of ​​dichotomy, a more accurate numerical solution can be obtained with the help of Matlab programming. The specific steps ...

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Abstract

The invention discloses a nonlinear detection method for high-cycle fatigue damage of a metal sheet. The method is suitable for detection and characterization of fatigue early-stage micro-defects and micro-damages in the metal sheet, and belongs to the field of nondestructive testing. The method comprises the steps: firstly, determining the excitation frequency of a fundamental frequency wave according to a measured object and a nonlinear Lamb wave resonance condition; arranging a pair of detection probes, namely an ultrasonic transmitting probe and an ultrasonic receiving probe, in the same side direction of a test piece, and carrying out nonlinear detection on the metal sheet structure; scanning different positions of the test piece by changing the excitation time delay of an excitation signal, and extracting a fundamental wave amplitude and a second harmonic amplitude; and finally, according to the change rule of the ultrasonic nonlinear coefficient along with the detection position, achieving detection of the fatigue damage of the metal plate and characterization of the damage degree. According to the invention, a band-pass filter at a certain frequency is introduced, and an original high-pass filter is replaced by the band-pass filter, so that the received signal is purer, and meanwhile, the data processing difficulty is greatly reduced.

Description

technical field [0001] The invention relates to the technical field of high-cycle fatigue damage detection of metal materials, in particular to a nonlinear wave detection method for high-cycle fatigue damage of thin metal plates. Background technique [0002] As an important energy conversion device, centrifugal compressor is widely used in important fields such as electric power, energy, metallurgy, petroleum, and chemical industry. The impeller and blade are the core modules of the centrifugal compressor, and FV520B high-strength steel is used as a common material for making the impeller and blade. Because of the harsh working environment, complex load bearing and long service time, fatigue failure is often prone to occur. For well-designed structural parts, early fatigue damage of materials (before the formation of macroscopic cracks) occupies a large proportion of the entire fatigue life, and for fatigue-damaged structural parts, its early performance degradation account...

Claims

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Application Information

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IPC IPC(8): G01N29/04G01N29/12
CPCG01N29/041G01N29/12G01N2291/0234G01N2291/0289
Inventor 陈冰冰周启文王鹏飞杜超郑三龙王超
Owner ZHEJIANG UNIV OF TECH
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