CN107024535A - A kind of multiple index depth detection method of the vertical defect based on surface wave - Google Patents
A kind of multiple index depth detection method of the vertical defect based on surface wave Download PDFInfo
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- CN107024535A CN107024535A CN201610195694.8A CN201610195694A CN107024535A CN 107024535 A CN107024535 A CN 107024535A CN 201610195694 A CN201610195694 A CN 201610195694A CN 107024535 A CN107024535 A CN 107024535A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/041—Analysing solids on the surface of the material, e.g. using Lamb, Rayleigh or shear waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0426—Bulk waves, e.g. quartz crystal microbalance, torsional waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0428—Mode conversion
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Abstract
A kind of multiple index depth detection method of the vertical defect based on surface wave, belongs to supersonic guide-wave Non-Destructive Testing and evaluation areas.Surface wave is in communication process, the bulk wave of scattering is had when being interacted with defect below defect, the lower surface that bodily wave propagation runs into workpiece can be reflected, surface wave such as (namely mode conversion echo) can be converted to once again and be propagated along defect two ends by running into defect, and it is with the total distance that the time difference of flaw echo is that shear wave is propagated in thickness of workpiece direction.The mode conversion echo at defect two ends with flaw echo and transmitted wave synthesis can as depth of defect characterization parameter, the depth detection method of the vertical defect of multiple index is solved brings inaccuracy and unworthiness for the detection more than 0.45 times of wavelength depth of defect at present.In health monitoring and Nondestructive Evaluation field, with great application value and potentiality.
Description
Technical field
The present invention relates to a kind of multiple index depth detection method of the vertical defect based on surface wave, belong to supersonic guide-wave without
Damage detection and evaluation areas.
Background technology
Using surface wave to carry out, Surface Flaw Detection is especially vertical to surface or the vertical defect of class is carried out at present
When depth detection, according to parameter informations such as the size of workpiece, materials, pass through pop one's head in transmitting specific frequency or specific wavelength
Surface wave carries out defects detection.Excitating surface ripple and flaw echo are calculated according to resulting signal waveform (self excitation and self receiving)
Time difference Δ t, is multiplied by time difference Δ t with the known surface wave velocity of wave v in this workpiece and draws the total distance that surface wave is propagated,
The position of defect is determined with the half of total distance.For the detection of depth of defect, often a form received is swashed using one.Enter first
The foundation of row emulation coefficient curve, the signal waveform received according to receiving transducer records and calculates the amplitude of direct wave, defect
The amplitude of echo and the amplitude of transmitted wave, on the basis of through wave amplitude, with the amplitude and the width of transmitted wave of flaw echo
The coefficient for obtaining characterizing depth of defect information is normalized in value divided by through wave amplitude.Work is determined further according to related experiment
The characterization parameter of part depth of defect, the detection that coefficient of correlation curve carries out depth of defect is determined.But, depth of defect characterizes coefficient
Simply show preferable monotonicity in the range of depth of defect is 0.45 times of wavelength, depth of defect be 0.45 times of wavelength with
The opposite shape condition of monotonicity is showed in scope afterwards, that is to say, that whole piece coefficient curve is in general 0.45 times of wavelength depth of defect
There is flex point at place.This just brings inaccuracy and unworthiness for the detection more than 0.45 times of wavelength depth of defect.
The content of the invention
For above-mentioned existing problem, the multiple index that the present invention proposes a kind of vertical defect based on surface wave is deep
Detection method is spent, solves and brings inaccuracy and inapplicable for the detection more than 0.45 times of wavelength depth of defect at present
Property.Surface wave has the bulk wave of scattering in communication process below defect when being interacted with defect, bodily wave propagation runs into work
The lower surface of part can be reflected, and surface wave such as accompanying drawing 1-2 (namely mode conversion echo) can be converted to once again by running into defect
And propagated along defect two ends, it is with the total distance that the time difference of flaw echo is that shear wave is propagated in thickness of workpiece direction.Defect
The mode conversion echo at two ends with flaw echo and transmitted wave synthesis can as depth of defect characterization parameter, multiple index
The depth detection method of vertical defect solve brought at present for the detection more than 0.45 times of wavelength depth of defect it is inaccurate
Property and unworthiness.
Step 1：Establish emulation polyphyly number curve
The parameter informations such as size and material for target workpiece, it is determined that suitable simulation software, sets up suitable emulation
Model.According to required, depth of defect size range is determined, serial emulation is carried out.According to simulation model, extract at observation station or face
Shape information, with resulting flaw echo value, transmission wave number and defect two ends at mode conversion echo (such as accompanying drawing 1)
As ordinate after value divided by the through wave number normalized of benchmark, then with depth of defect or depth of defect divided by wavelength normalization
Processing sets up multiple index depth of defect and characterizes curve (such as accompanying drawing 2) as abscissa.
Step 2：Carry out experiment detection
The stimulating frequency set up according to the size of target workpiece and material parameter information and emulation polyphyly number curve and swash
Originating party formula, the suitable probe of selection is tested.As shown in figure 3, experimental system includes test piece, a sharp receipts probe, shown
Ripple device, excitation set；One swashs a receipts probe is connected with test piece, and one sharp one, which receives probe, passes through connecting line and excitation set company
Connect, excitation set is connected with oscillograph.The mode that experiment measures at the defect clawback, transmitted wave and defect two ends of test piece turns
Ripple (such as accompanying drawing 1) is gained, record obtains the waveforms amplitude of four sign depth of defects of the above.
Step 3：Determine depth of defect
Four defect informations of mode conversion echo at defect clawback, transmitted wave and defect two ends measured according to experiment,
Divided by a reference value direct wave obtains one group of four coefficient value.One group of four coefficient depth of defect obtained by contrast simulation characterizes bent
Line, determines the depth of defect.
Multiple index includes flaw echo depth of defect and characterizes coefficient, transmitted wave depth of defect sign coefficient, defect left end mould
State conversion echo depth of defect characterizes coefficient, defect right-hand member mode conversion echo depth of defect and characterizes coefficient；Flaw echo defect
Depth characterizes coefficient to run into the flaw echo that defect reflection is returned during surface wave propagation, and it is according to for different depth
The flaw echo depth of defect sign coefficient that the flaw echo amplitude that defect reflection is returned is different and sets up；Transmitted wave depth of defect
Coefficient is characterized to run into the transmitted wave that defect continues to propagate through defect during surface wave propagation, it is according to for different depths
The transmitted wave depth of defect spent the transmission wave amplitude difference of defect transmissive and set up characterizes coefficient；Defect left end mode conversion
Echo depth of defect characterize coefficient be surface wave in communication process, scattering is had below defect when being interacted with defect
Bulk wave, the lower surface that bodily wave propagation runs into workpiece can be reflected, and running into defect can be converted to along the propagation of defect left end once again
Surface wave, it is according to the defect left end mode turn that the defect defect left end mode conversion echo amplitude of different depth is different and sets up
Gain ripple depth of defect and characterize coefficient；Defect right-hand member mode conversion echo depth of defect sign coefficient is surface wave in communication process
In, the bulk wave of scattering is had when being interacted with defect below defect, the lower surface that bodily wave propagation runs into workpiece can be reflected back
Come, the surface wave propagated along defect right-hand member can be converted to once again by running into defect, and it is according to the defect defect right-hand member mould of different depth
The defect right-hand member mode conversion echo depth of defect that state converts back wave amplitude difference and set up characterizes coefficient.
Brief description of the drawings
Mode conversion echo simulation figure of Fig. 1 surface waves at defect two ends；
Figure 25 00kHz multiple indexs depth of defect characterizes curve；
Fig. 3 tests schematic diagram；
Fig. 4 COMSOL simulation models；
Propagation of Figure 55 00kHz lower surface ripples in aluminium sheet；
Defect clawback and mode conversion echo information under Figure 65 00kHz；
Fig. 7 Electromagnetic Acoustic Transducer schematic diagrames；
Fig. 8 experiments measure mode conversion echo on the left of flaw echo and defect；
Fig. 9 experiments measure mode conversion echo on the right side of transmitted wave and defect；
Embodiment
Present disclosure is described in further detail below in conjunction with 500kHz examples：
Step 1：Establish emulation polyphyly number curve
The parameter informations such as size and material for target workpiece, determine COMSOL simulation softwares, set up suitable emulation
Model (such as accompanying drawing 4).According in target workpiece surface wave velocity of wave be 3000m/s, calculatings wavelength be 6mm, determine depth of defect
Size range is 0-7.2mm, carries out serial emulation (such as accompanying drawing 5).According to simulation model, the shape information at observation station is extracted,
The shape information at observation station is read with MATlab and to carry out Hilbert transform (such as accompanying drawing 6) more accurate to ensure to obtain
Amplitude information.Extract the maximum at ripple bag：Turned with the mode at obtained flaw echo value, transmission wave number and defect two ends
Handled after gaining wave number divided by the through wave number normalized of benchmark as ordinate, then with depth of defect divided by wavelength normalization
As abscissa, set up multiple index depth of defect and characterize curve (such as accompanying drawing 2).
Step 2：Carry out experiment detection
The stimulating frequency that the parameter informations such as size and material according to target workpiece and emulation polyphyly number curve are set up
500kHz and point mode of excitation, selection Electromagnetic Acoustic Transducer (such as accompanying drawing 7) carry out experiment detection.As shown in Figure 3, experimental system
Steel plate including 400mm*650mm*25mm, one swash one and receive receiving transducer, oscillograph, excitation set.Experiment measures workpiece, defect
Mode conversion echo (such as accompanying drawing 8-9) at clawback, transmitted wave and defect two ends, record obtains four sign depth of defects of the above
Waveforms amplitude.
Step 3：Determine depth of defect
Four defect informations of mode conversion echo at defect clawback, transmitted wave and defect two ends measured according to experiment,
It is read out and is handled with MATlab, is most worth with amplitude divided by a reference value direct wave obtains one group of four coefficient value.Contrast simulation
One group of resulting four coefficient depth of defect characterizes curve, determines the depth 1mm of defect.
A kind of depth of the vertical defect of plate based on surface wave provided above with 500kHz exemplary operations the present invention is examined
Survey method is described.The explanation of above example, which is served mainly to facilitate, understands that surface wave is produced in being interacted with defect
Mode conversion echo it is very important, returned for the mode conversion added in traditional defect clawback, transmitted wave at defect two ends
Ripple can preferably characterize the depth of defect, to break through the limitation of flex point at 0.45 times of wavelength depth of defect；Simultaneously for ability
The those skilled in the art in domain, the method according to the present invention is had in variation, this specification in embodiment and scope
Appearance should not be construed as limiting the invention.
Claims (1)
1. a kind of multiple index depth detection method of the vertical defect based on surface wave, it is characterised in that：This method includes flow
It is as follows：
Step 1：Establish emulation polyphyly number curve
The parameter informations such as size and material for target workpiece, it is determined that suitable simulation software, sets up suitable simulation model；
According to required, depth of defect size range is determined, serial emulation is carried out；According to simulation model, the ripple at observation station or face is extracted
Shape information is straight with the mode conversion Echo Rating divided by benchmark at resulting flaw echo value, transmission wave number and defect two ends
As ordinate after up to wave number normalized, then using depth of defect or depth of defect divided by wavelength normalization processing be used as it is horizontal sit
Mark, sets up multiple index depth of defect and characterizes curve；
Step 2：Carry out experiment detection
The stimulating frequency set up according to the size of target workpiece and material parameter information and emulation polyphyly number curve and the side of exciting
Formula, the suitable probe of selection is tested；Experimental system includes test piece, a sharp receipts probe, oscillograph, excitation set；
One swash one receive probe is connected with test piece, one swash one receive probe is connected by connecting line with excitation set, excitation set and
Oscillograph is connected；Experiment measures the mode conversion echo at the defect clawback, transmitted wave and defect two ends of test piece, records
The waveforms amplitude of four sign depth of defects more than；
Step 3：Determine depth of defect
Four defect informations of mode conversion echo at defect clawback, transmitted wave and defect two ends measured according to experiment, divided by
A reference value direct wave obtains one group of four coefficient value；One group of four coefficient depth of defect obtained by contrast simulation characterizes curve,
Determine the depth of defect；
Multiple index includes flaw echo depth of defect and characterizes coefficient, transmitted wave depth of defect sign coefficient, defect left end mode turn
Gain ripple depth of defect and characterize coefficient, defect right-hand member mode conversion echo depth of defect sign coefficient；Flaw echo depth of defect
Coefficient is characterized to run into the flaw echo that defect reflection is returned during surface wave propagation, it is according to for different deep defects
The flaw echo depth of defect sign coefficient that the flaw echo amplitude reflected is different and sets up；Transmitted wave depth of defect is characterized
Coefficient is runs into the transmitted wave that defect continues to propagate through defect during surface wave propagation, it is according to scarce for different depth
The transmitted wave depth of defect for falling into the transmission wave amplitude difference of transmissive and setting up characterizes coefficient；Defect left end mode conversion echo
Depth of defect characterize coefficient be surface wave in communication process, the body of scattering is had when being interacted with defect below defect
Ripple, the lower surface that bodily wave propagation runs into workpiece can be reflected, and the table propagated along defect left end can be converted to once again by running into defect
Face ripple, it is according to the defect left end mode conversion that the defect defect left end mode conversion echo amplitude of different depth is different and sets up
Echo depth of defect characterizes coefficient；Defect right-hand member mode conversion echo depth of defect sign coefficient is surface wave in communication process
In, the bulk wave of scattering is had when being interacted with defect below defect, the lower surface that bodily wave propagation runs into workpiece can be reflected back
Come, the surface wave propagated along defect right-hand member can be converted to once again by running into defect, and it is according to the defect defect right-hand member mould of different depth
The defect right-hand member mode conversion echo depth of defect that state converts back wave amplitude difference and set up characterizes coefficient.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108645920A (en) * | 2018-04-09 | 2018-10-12 | 华南理工大学 | A kind of direct wave suppressing method of the rail flaw ultrasonic detection based on denoising and alignment |
| CN109900788A (en) * | 2019-03-18 | 2019-06-18 | 阜阳师范学院 | A kind of device and measurement method can be used for carrying out the sound absorption characteristics of acoustical material in-site measurement |
| CN110363767A (en) * | 2019-08-09 | 2019-10-22 | 中国特种设备检测研究院 | A kind of gridding ultrasound tomography detection method of shaft-like workpiece defect |
| CN113325072A (en) * | 2021-04-30 | 2021-08-31 | 北京航空航天大学 | Metal plate corrosion damage depth evaluation system and method |
| CN115406383A (en) * | 2021-05-28 | 2022-11-29 | 中国石油天然气股份有限公司 | Method for detecting corrosion depth of storage tank top |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101398411A (en) * | 2008-11-07 | 2009-04-01 | 哈尔滨工业大学 | Rail tread defect rapid scanning and detecting method and device thereof |
| CN101571513A (en) * | 2009-06-16 | 2009-11-04 | 北京理工大学 | Ultrasonic guided wave detection device for quality evaluation of composite laminated plate |
| CN102809610A (en) * | 2012-06-04 | 2012-12-05 | 北京航空航天大学 | Phased array ultrasonic testing method based on improved dynamic depth focusing |
| CN105102975A (en) * | 2013-04-02 | 2015-11-25 | 杰富意钢铁株式会社 | Ultrasonic flaw-detection method and ultrasonic flaw-detection device |
-
2016
- 2016-03-30 CN CN201610195694.8A patent/CN107024535B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101398411A (en) * | 2008-11-07 | 2009-04-01 | 哈尔滨工业大学 | Rail tread defect rapid scanning and detecting method and device thereof |
| CN101571513A (en) * | 2009-06-16 | 2009-11-04 | 北京理工大学 | Ultrasonic guided wave detection device for quality evaluation of composite laminated plate |
| CN102809610A (en) * | 2012-06-04 | 2012-12-05 | 北京航空航天大学 | Phased array ultrasonic testing method based on improved dynamic depth focusing |
| CN105102975A (en) * | 2013-04-02 | 2015-11-25 | 杰富意钢铁株式会社 | Ultrasonic flaw-detection method and ultrasonic flaw-detection device |
Non-Patent Citations (2)
| Title |
|---|
| 关建飞等: "表面垂直裂痕诱发瑞利波散射的数值分析", 《应用声学》 * |
| 赵继辰等: "螺旋波纹管导波检测技术的数值仿真和试验研究", 《机械工程学报》 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108645920A (en) * | 2018-04-09 | 2018-10-12 | 华南理工大学 | A kind of direct wave suppressing method of the rail flaw ultrasonic detection based on denoising and alignment |
| CN108645920B (en) * | 2018-04-09 | 2020-12-22 | 华南理工大学 | Denoising and alignment-based direct wave suppression method for ultrasonic flaw detection of steel rail |
| CN109900788A (en) * | 2019-03-18 | 2019-06-18 | 阜阳师范学院 | A kind of device and measurement method can be used for carrying out the sound absorption characteristics of acoustical material in-site measurement |
| CN110363767A (en) * | 2019-08-09 | 2019-10-22 | 中国特种设备检测研究院 | A kind of gridding ultrasound tomography detection method of shaft-like workpiece defect |
| CN110363767B (en) * | 2019-08-09 | 2021-04-02 | 中国特种设备检测研究院 | Gridding ultrasonic tomography detection method for shaft workpiece defects |
| CN113325072A (en) * | 2021-04-30 | 2021-08-31 | 北京航空航天大学 | Metal plate corrosion damage depth evaluation system and method |
| CN115406383A (en) * | 2021-05-28 | 2022-11-29 | 中国石油天然气股份有限公司 | Method for detecting corrosion depth of storage tank top |
| CN115406383B (en) * | 2021-05-28 | 2024-05-28 | 中国石油天然气股份有限公司 | Method for detecting corrosion depth of top of storage tank |
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