CN110231394A - The irregular crackle imaging method of nonferromugnetic material based on ac magnetic field - Google Patents
The irregular crackle imaging method of nonferromugnetic material based on ac magnetic field Download PDFInfo
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Abstract
The invention discloses a kind of irregular crackle imaging methods of nonferromugnetic material based on alternating current field measurement, it is related to nondestructive detecting defect technical field of imaging, it include: to obtain alternating electromagnetic scene by grid checking method to sweep resultant magnetic fields signal Bz amplitude matrix, the gradient field matrix of distorted magnetic field signal Bz maximum distortion numerical value is obtained using gradient fields, reflect induced current in the aggregation situation of irregular crackle endpoint and edge, further by seeking extreme value, dispel background, normalization operation and gradation conversion, obtain the irregular intuitive imaging results of crackle surface profile of nonferromugnetic material, the visualization assessment and remaining life for being advantageously implemented nonferromugnetic material crackle are precisely predicted.
Description
Technical field
The present invention relates to nondestructive detecting defect technical field of imaging, more particularly to one kind to be based on alternating current field measurement technology
The irregular crackle imaging method of nonferromugnetic material.
Background technique
The non-ferromagnetic conductive materials such as stainless steel, aluminium alloy have a wide range of applications in industrial circle, due to for a long time in corruption
It is on active service in erosion medium, complex stress environment, material surface can produce various irregular crackles, and the safety of structure is threatened to be on active service.It hands over
Galvanic electricity magnetic field detection (Alternating Current Field Measurement-ACFM) technology be a kind of emerging electromagnetism without
Detection technique is damaged, is mainly used for conductive material surface crack detection, is induced using detection probe in conductive surface of test piece
Uniform current, electric current generate disturbance around defect and space magnetic field are caused to distort, and the inspection of defect is carried out by measurement distorted magnetic field
It surveys and assesses.In the presence of zero defect, conductive surface of test piece electric current is in uniform state, space magnetic field undisturbed.
In existing non-destructive testing technology, the technologies such as magnetic powder, leakage field are only used for ferrimagnet defects detection；It is ultrasonic main
For Inner Defect Testing；The waste liquid that Liquid penetrant testing needs to dispel coating and generates to body structure surface thorough cleaning, detection process
Pollution can be generated to environment；Eddy detection technology is difficult to realize the imaging of the irregular crackle of any direction by impedance analysis method
Display.Alternating current field measurement technology has outstanding advantage in conductive material surface field of crack detection, at present ac magnetic field
Detection technique is determined according to the butterfly diagram of characteristic signal Bx and Bz or its composition, wherein Bx with Bz signal is respectively parallel
In surface of test piece (parallel with probe scanning direction) and perpendicular to the magnetic field signal of surface of test piece, this feature signal can only determine to lack
Sunken presence, and regular crack is assessed, the imaging that cannot achieve irregular crackle is shown, cannot intuitively be shown irregular
The surface profile of crackle.
Therefore, it is necessary to propose that a kind of intuitive is good, can be realized nonferromugnetic material surface imperfection crackle imaging side
Method is presented the surface profile visualization pattern of irregular crackle, provides essence for the defect estimation of nonferromugnetic material, life prediction
Quasi- data supporting.
Summary of the invention
In view of the above-mentioned problems, the present invention provides a kind of nonferromugnetic materials based on alternating current field measurement technology not to advise
Then crackle imaging method is intuitively presented the surface profile visualization pattern of irregular crackle, comments for the defect of nonferromugnetic material
Estimate, life prediction provides accurate, visualized data support.
The present invention provides a kind of irregular crackle imaging method of nonferromugnetic material based on alternating current field measurement, packets
It includes:
Step 1 is popped one's head in using alternating current field measurement and obtains the irregular crackle of nonferromugnetic material with grid scanning mode
Top same plane different location magnetic field signal Bz amplitude, definition probe scanning direction is X-direction, in the scanning path of X-direction
Equidistant n location point is extracted, extracting equidistant scanning number of path in the direction vertical with probe scanning direction is m, by above
The magnetic field signal Bz amplitude of location point forms m row n column matrixTo each row element [a of matrix Ai1 ai2
… ain] along the X direction (matrix A line direction) seek gradientObtain the gradient fields of matrix A
Matrix
Step 2 seeks the extreme value PGX in the gradient fields matrix B all elementsBz, determine extreme value PGXBzWhether it is less than
0, if it is multiplied by -1, obtain positive peak Matrix C；
Step 3 determines that whether each element if it is multiplied by 0, obtains dispel back less than 0 in positive peak Matrix C
Scape matrix D；
The amplitude for dispelling background matrix D all elements is normalized to the section 0-1, obtains normalization matrix E by step 4,
Irregular crackle surface profile color image F is drawn by the corresponding coordinate position of each element of normalization matrix E；
The color image F is converted to grayscale image G by step 5, obtains the irregular crack surfaces wheel of nonferromugnetic material
Wide image.
The irregular crackle imaging method of nonferromugnetic material provided by the invention based on alternating current field measurement technology leads to
It crosses and X-direction gradient is sought to characteristic signal Bz amplitude, obtain the gradient field matrix for being able to reflect current collection position, further body
The now Endpoint location information of irregular crackle determines that element extreme value and step 3 in gradient field matrix dispel back by step 2
Scape field algorithm can obtain the posivtive spike value matrix of reflection crack surfaces contour images, by step 4 normalization and step 5 gray scale
Cromogram is changed into grayscale image by conversion, can intuitively reflect that the irregular crackle any angle surface profile of nonferromugnetic material can
Depending on changing image.
Detailed description of the invention
Fig. 1 is the irregular crackle imaging side of the nonferromugnetic material provided by the invention based on alternating current field measurement technology
Method flow chart；
Fig. 2 is stainless steel test block provided in an embodiment of the present invention and irregular crackle photo；
Fig. 3 is the irregular crackle of stainless steel surface of test piece provided in an embodiment of the present invention and grid scanning path schematic diagram；
Fig. 4 is the grid scanning different location point magnetic field provided in an embodiment of the present invention based on alternating current field measurement technology
The cromogram that signal Bz amplitude matrix is formed；
Fig. 5 is the image that gradient fields matrix provided in an embodiment of the present invention is formed；
Fig. 6 is the image provided in an embodiment of the present invention for seeking extreme value and dispel matrix formation after background；
Fig. 7 is normalized image provided in an embodiment of the present invention；
Fig. 8 is the visual image provided in an embodiment of the present invention that irregular crackle surface profile is presented.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, with reference to the accompanying drawing and specific embodiment to this
Invention is described in further detail, it is clear that described embodiment is a part of the embodiment of the present invention, rather than all real
Apply example.Based on the embodiment of the present invention, those skilled in the art obtain without creative efforts other
Embodiment shall fall within the protection scope of the present invention.
In embodiments of the present invention, the method is applied to the nonferromugnetic material based on alternating current field measurement technology not
The imaging of regular crack surface profile obtains alternating electromagnetic scene by grid checking method first and sweeps resultant magnetic fields signal Bz amplitude
Matrix obtains the Bz maximum distortion of distorted magnetic field signal using gradient fields according to the principle of ac magnetic field current collection and disturbance
The gradient field matrix of numerical value, reflection induced current further pass through and seek in the aggregation situation of irregular crackle endpoint and edge
Extreme value dispels background, normalization operation and gradation conversion, obtains the irregular crackle surface profile of nonferromugnetic material and is intuitively imaged
As a result, being advantageously implemented the visualization assessment of nonferromugnetic material crackle and remaining life is precisely predicted.
Embodiment one
Fig. 1 is the irregular crackle of the nonferromugnetic material provided in an embodiment of the present invention based on alternating current field measurement technology
Imaging method flow chart, comprising:
S1 prepares stainless steel test block, and test block surface is equipped with irregular crackle, as shown in Fig. 2, the wide 0.5mm of irregular crackle,
It is formed respectively by 0 °, 30 °, 60 ° and 90 ° four sections of crackles are presented, every section of crackle long 30.0mm, deep 4.0mm.Define probe scanning
Direction is X-direction, using grid checking method, is popped one's head in using alternating current field measurement in the same height of the irregular crack surfaces of test block
Spend plane along the region scanning path detection 48mm × 48mm, as shown in Figure 3.X-direction scanning step-length is 2.0mm, and X-direction is taken to sweep
Looking into equally spaced position points on path is 25, and the spacing in scanning path is 2.0mm in the Y direction, takes the equidistant scanning path of Y-direction
Number is 25, obtains the magnetic field signal Bz amplitude of the above location point, and forming line number m is 25, the matrix A that columns n is 25, matrix A
Partial Elements are as follows:
For the size of element in visual representation matrix A, using abscissa (X-direction) and the corresponding position of ordinate (Y-direction)
The magnetic field signal Bz amplitude set a little draws planar coloured figure, as shown in Figure 4.It can be seen that magnetic field signal Bz amplitude exists in matrix A
It is disturbed around irregular crackle, positive negative peak is presented, can not intuitively show the surface profile of crackle.To each in matrix A
Capable element seeks gradient according to X-directionGradient fields matrix B is obtained, respective coordinates are utilized
The gradient fields matrix B of location point draws gradient fields matrix image, as shown in Figure 5.It can be seen that positive peak is presented in gradient field matrix
And negative peak needs to carry out seeking in step s 2 to gradient fields matrix B extreme value processing for maximum extreme value of seeking to distort.
S2: the extreme value PGX in the gradient fields matrix B all elements is soughtBz, extreme value PGX in the present embodimentBzFor positive value,
Due to PGXBzGreater than 0, without carrying out element replacement processing, gradient fields matrix B is changed into positive peak Matrix C, is directly entered step
Rapid S3 processing, dispels the background value less than 0.
S3: determine that each element, will be in positive peak Matrix C if it is multiplied by 0 whether less than 0 in positive peak Matrix C
All elements less than 0 become 0, and positive peak Matrix C element background value Numerical Implementation uniformly returns 0 processing, obtain dispelling background matrix
D, as shown in Figure 6.The surface profile of crackle can be substantially presented in Fig. 6, in order to more highlight surface profile, will dispel background matrix D
Enter step 4 normalizeds.
S4 will dispel the amplitude of background matrix D all elements divided by extreme value PGXBz, background matrix D will be dispelled and normalized to
The section 0-1 obtains normalization matrix E, draws irregular crackle table by the corresponding coordinate position of each element of normalization matrix E
Facial contour color image F, as shown in Figure 7.Fig. 7 cromogram can intuitively show the surface profile of irregular crackle, for reality
Existing crackle visualization processing, enters step 5 carry out grayscale image conversions for Fig. 7 cromogram.
The color image F is converted to grayscale image G using Matlab, obtains the irregular crackle of nonferromugnetic material by S5
Surface profile image, as shown in Figure 8.The visualization pattern of irregular crackle can be more clearly presented in Fig. 8, with stainless steel test block
Surface imperfection crackle quite well, reaches higher inversion accuracy.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can easily think of the change or the replacement, and should all contain
Lid is within protection scope of the present invention.Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (5)
1. a kind of irregular crackle imaging method of nonferromugnetic material based on alternating current field measurement, which is characterized in that including
Step 1:
It is popped one's head in using alternating current field measurement and obtains same plane different location magnetic field above the irregular crackle of nonferromugnetic material
Signal Bz amplitude, definition probe scanning direction is X-direction, in the equidistant n location point of the scanning path extraction of X-direction, with
It is m that equidistant scanning number of path is extracted in the vertical direction in probe scanning direction, by the magnetic field signal Bz amplitude shape of the above location point
At m row n column matrixTo each row element [a of matrix Ai1 ai2 … ain] (matrix A row along the X direction
Direction) seek gradientObtain the gradient field matrix of matrix A
2. the irregular crackle imaging method of the nonferromugnetic material according to claim 1 based on alternating current field measurement,
It is characterised in that it includes step 2:
Seek the extreme value PGX in the gradient fields matrix B all elementsBz, determine extreme value PGXBzWhether less than 0, if it is multiply
With -1, positive peak Matrix C is obtained.
3. the irregular crackle imaging method of the nonferromugnetic material according to claim 1 based on alternating current field measurement,
It is characterised in that it includes step 3:
Determine that whether each element if it is multiplied by 0, obtains dispel background matrix D less than 0 in positive peak Matrix C.
4. the irregular crackle imaging method of the nonferromugnetic material according to claim 1 based on alternating current field measurement,
It is characterised in that it includes step 4:
The amplitude for dispelling background matrix D all elements is normalized into the section 0-1, normalization matrix E is obtained, by normalization matrix
The corresponding coordinate position of each element of E draws irregular crackle surface profile color image F.
5. the irregular crackle imaging method of the nonferromugnetic material according to claim 1 based on alternating current field measurement,
It is characterised in that it includes step 5:
The color image F is converted into grayscale image G, obtains the irregular crackle surface profile map picture of nonferromugnetic material.
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Cited By (8)
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| CN111189905A (en) * | 2020-01-09 | 2020-05-22 | 中国石油大学(华东) | Three-dimensional size evaluation method for corrosion defects of underwater structure based on alternating-current electromagnetic field |
| CN111189906A (en) * | 2020-01-09 | 2020-05-22 | 中国石油大学(华东) | Online intelligent judgment and classification identification method for defects of alternating current magnetic field |
| CN111398409A (en) * | 2020-01-09 | 2020-07-10 | 中国海洋石油集团有限公司 | Underwater conductive metal material crack section reconstruction method based on alternating current electromagnetic field |
| CN112857197A (en) * | 2021-04-09 | 2021-05-28 | 中国石油大学(华东) | Rotating electromagnetic field non-ferromagnetic material crack size measurement method |
| CN112964777A (en) * | 2021-04-14 | 2021-06-15 | 中国特种设备检测研究院 | Double-excitation detection method for surface crack trend |
| CN114234785A (en) * | 2021-12-23 | 2022-03-25 | 中国特种设备检测研究院 | Method for detecting cracks on surface and near surface of connecting pipe fillet weld based on field gradient imaging |
| CN117074513A (en) * | 2023-10-13 | 2023-11-17 | 中国石油大学(华东) | Defect identification method based on alternating current electromagnetic field and array detection probe |
| CN118154586A (en) * | 2024-05-09 | 2024-06-07 | 深圳市冠森高捷电子技术有限公司 | Intelligent connector crack defect detection method based on machine vision |
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| CN111398409B (en) * | 2020-01-09 | 2023-04-21 | 中国海洋石油集团有限公司 | Underwater conductive metal material crack profile reconstruction method based on alternating current electromagnetic field |
| CN111189906A (en) * | 2020-01-09 | 2020-05-22 | 中国石油大学(华东) | Online intelligent judgment and classification identification method for defects of alternating current magnetic field |
| CN111398409A (en) * | 2020-01-09 | 2020-07-10 | 中国海洋石油集团有限公司 | Underwater conductive metal material crack section reconstruction method based on alternating current electromagnetic field |
| CN111189905A (en) * | 2020-01-09 | 2020-05-22 | 中国石油大学(华东) | Three-dimensional size evaluation method for corrosion defects of underwater structure based on alternating-current electromagnetic field |
| CN111189906B (en) * | 2020-01-09 | 2023-09-29 | 中国石油大学(华东) | On-line intelligent judging and classifying identification method for alternating current magnetic field defects |
| CN111189905B (en) * | 2020-01-09 | 2023-09-05 | 中国石油大学(华东) | Three-dimensional size assessment method for corrosion defect of underwater structure based on alternating-current electromagnetic field |
| CN112857197A (en) * | 2021-04-09 | 2021-05-28 | 中国石油大学(华东) | Rotating electromagnetic field non-ferromagnetic material crack size measurement method |
| CN112857197B (en) * | 2021-04-09 | 2022-04-19 | 中国石油大学(华东) | Rotating electromagnetic field non-ferromagnetic material crack size measurement method |
| CN112964777A (en) * | 2021-04-14 | 2021-06-15 | 中国特种设备检测研究院 | Double-excitation detection method for surface crack trend |
| CN112964777B (en) * | 2021-04-14 | 2024-02-06 | 中国特种设备检测研究院 | Double-excitation detection method for surface crack trend |
| CN114234785A (en) * | 2021-12-23 | 2022-03-25 | 中国特种设备检测研究院 | Method for detecting cracks on surface and near surface of connecting pipe fillet weld based on field gradient imaging |
| CN117074513A (en) * | 2023-10-13 | 2023-11-17 | 中国石油大学(华东) | Defect identification method based on alternating current electromagnetic field and array detection probe |
| CN117074513B (en) * | 2023-10-13 | 2023-12-15 | 中国石油大学(华东) | Defect identification method based on alternating current electromagnetic field and array detection probe |
| CN118154586A (en) * | 2024-05-09 | 2024-06-07 | 深圳市冠森高捷电子技术有限公司 | Intelligent connector crack defect detection method based on machine vision |
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