CN106442708B - Stress evaluation method based on domain motion threshold field - Google Patents
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Abstract
The invention discloses a kind of stress evaluation methods based on domain motion threshold field, for each stress parameters, it obtains the normalization magnetic domain quantized value under different magnetic field intensity: first obtaining domain pattern of the feeromagnetic metal component under stress parameters and magnetic field strength, binaryzation again after being pre-processed to domain pattern, statistics represents the pixel quantity of 180 degree and -180 degree magnetic domain, 180 degree magnetic domain area and -180 degree magnetic domain area are calculated, normalization magnetic domain quantized value is calculated；Fitting obtains the S that normalization magnetic domain quantized value changes with field strength valuesNom- H curve obtains 4 threshold fields, and fitting obtains expression formula of 4 threshold fields about stress parameters, when carrying out stress evaluation to feeromagnetic metal component, acquisition S firstNom- H curve obtains 4 threshold fields, and 4 stress values are calculated, and obtains final stress value after average.The present invention realizes the high linearity to feeromagnetic metal component stress and minimal stress variation, high sensitivity, high spatial resolution detection by threshold field.
Description
Technical field
The invention belongs to technical field of nondestructive testing, more specifically, are related to a kind of based on domain motion threshold field
Stress evaluation method.
Background technique
Now in the industry, feeromagnetic metal component, in railway traffic, aerospace, the departments such as metallurgical industry boiler, pipeline,
A large amount of uses of bridge, rail, pressure vessel etc., as active time extends, unavoidably there is stress in feeromagnetic metal component
Concentration phenomenon so that component fracture etc. and cause accident.Stress mornitoring ensures that feeromagnetic metal component is on active service safely in engineering
Important means.Traditional magnetic stress detection includes the skills such as hysteresis loop method, Barkhausen's method (MBN), detection method of eddy, magnetic memory method
Art.These traditional technologies establish macroscopical parameter of magnetic characteristic such as coercivity, remanent magnetism, magnetic domain loss from material macroscopic view magnetic characteristic
With the corresponding relationship of stress, has the shortcomings that sensitivity is low, spatial resolution is not high to stress evaluation, can not accurately assess ferromagnetic
The stress state of property material microcosmos area.
In recent years, with observation of magnetic domain technological progress, the dynamic behaviour of magnetic microstructure is gradually obtained in field of non destructive testing
It is widely applied.Magnetic domain dynamic behaviour, which is assessed, can be achieved the quickly detection of feeromagnetic metal component inside stress high-resolution, high-precision.
However, magnetic domain characterization is also limited to qualitative description, the quantization of domain motion characteristic and its evaluation studies country to stress at present
It is in space state outside.
Summary of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide a kind of stress based on domain motion threshold field
Appraisal procedure realizes the high linearity changed to feeromagnetic metal component stress and minimal stress, high sensitivity, high spatial resolution
Detection.
For achieving the above object, the present invention is based on the specific steps of the stress evaluation method of domain motion threshold field
Are as follows:
S1: the stress parameters collection φ={ σ simulated needed for feeromagnetic metal component determine according to actual needs1,σ2…,σKWith
And change of magnetic field strength range [- Hmax,Hmax], wherein K indicates stress parameters quantity, HmaxIndicate maximum field strength；
S2: setting stress parameters serial number k=1；
S3: by magnetic field strength H from-HmaxIt is gradually increased to Hmax, then gradually reduce to-Hmax, obtain stress parameters σkIt is lower every
The corresponding normalization magnetic domain quantized value S of a magnetic field strength HNom, the corresponding normalization magnetic domain quantized value S of each magnetic field strength HNom's
Acquisition methods the following steps are included:
S3.1: feeromagnetic metal component is obtained in stress parameters σkWith the domain pattern under magnetic field strength H；
S3.2: denoising is carried out to domain pattern；
S3.3: binaryzation is carried out to domain pattern, 180 degree magnetic domain is represented with 0 representative -180 degree magnetic domain, 1；
S3.4: to binaryzation domain pattern, in binaryzation domain pattern 0 and 1 pixel quantity is counted, is denoted as respectively
n-180°And n180°, calculate 180 degree magnetic domain areaWith -180 degree magnetic domain areaS is indicated
The area of single pixel point in domain pattern；Then magnetic domain quantized value Δ S is calculated according to the following formula:
S3.5: being normalized magnetic domain quantized value using following formula, obtains normalization magnetic domain quantized value SNom:
S4: according to the corresponding normalization magnetic domain quantized value S of magnetic field strength H each in step S3Nom, it is fitted and is currently answered
Force parameter σkThe S that lower normalization magnetic domain quantized value changes with field strength valuesNom- H curve；According to SNom- H curve obtains 4 orders
SNomFor 1 or -1 threshold limit value magnetic field Hth1(k)、Hth2(k)、Hth3(k)、Hth4(k)；
S5: if k < K, k=k+1, return step S3 is enabled otherwise to enter step S6；
S6: according to K stress parameters σkCorresponding 4 threshold fields carry out linear fit and obtain threshold field expression formula:
Hth1=a1σ+b1
Hth2=a2σ+b2
Hth3=a3σ+b3
Hth4=a4σ+b4
Wherein, am、bmIt is the linear dimensions in threshold field expression formula respectively, m=1,2,3,4；
S7: it when carrying out stress evaluation to feeromagnetic metal component, uses obtained with the same way in step S3 first
SNom- H curve obtains 4 threshold fields, then substitutes into the threshold field expression formula of step S6,4 stress value σ are calculated
(1), 4 stress value σ (1), σ (2), σ (3) and σ (4) are averagely obtained final stress value σ by σ (2), σ (3) and σ (4).
The present invention is based on the stress evaluation methods of domain motion threshold field to obtain different magnetic for each stress parameters
Normalization magnetic domain quantized value under field intensity, acquisition methods are as follows: first obtain feeromagnetic metal component in stress parameters and magnetic field strength
Under domain pattern, binaryzation again after being pre-processed to domain pattern, to binaryzation domain pattern statistics represent 180 degree and-
The pixel quantity of 180 degree magnetic domain calculates 180 degree magnetic domain area and -180 degree magnetic domain area, and magnetic domain quantization is then calculated
Value, then be normalized；Fitting obtains the S that normalization magnetic domain quantized value changes with field strength valuesNom- H curve obtains 4 thresholds
It is worth magnetic field, fitting obtains expression formula of 4 threshold fields about stress parameters, is carrying out stress evaluation to feeromagnetic metal component
When, acquisition S firstNom- H curve obtains 4 threshold fields, and 4 stress values then are calculated according to threshold field expression formula,
Final stress value is obtained after average.The present invention corresponding relationship between domain motion threshold field and stress after study proposes
Magnetic domain quantitative formula realizes high linearity, height to feeromagnetic metal component stress and minimal stress variation by threshold field
Sensitivity, high spatial resolution detection.
Detailed description of the invention
Fig. 1 is magneto-optical kerr microscope schematic diagram；
Fig. 2 is magneto-optic thin film structural schematic diagram；
Fig. 3 is magneto-optic thin film domain pattern illustraton of model under different situations；
Fig. 4 is magnetizing assembly block schematic illustration；
Fig. 5 is the domain pattern of highly oriented electrical sheet under 0MPa stress different magnetic field intensity；
Fig. 6 is the domain pattern of highly oriented electrical sheet under 30.9MPa stress different magnetic field intensity；
Fig. 7 is the domain pattern of highly oriented electrical sheet under 61.9MPa stress different magnetic field intensity；
Fig. 8 is the specific embodiment flow chart of the stress evaluation method the present invention is based on domain motion threshold field；
Fig. 9 is the acquisition flow chart for normalizing magnetic domain quantized value；
Figure 10 is to carry out domain pattern pretreatment exemplary diagram using wavelet filteration method in the present embodiment；
Figure 11 is that domain pattern binaryzation exemplary diagram is adopted in the present embodiment；
Figure 12 is SNom- H curve exemplary diagram；
Figure 13 is S under different stressNom- H curve and threshold field and stress relation exemplary diagram；
Figure 14 is the relationship contrast curve chart between different characteristic parameter and stress.
Specific embodiment
A specific embodiment of the invention is described with reference to the accompanying drawing, preferably so as to those skilled in the art
Understand the present invention.Requiring particular attention is that in the following description, when known function and the detailed description of design perhaps
When can desalinate main contents of the invention, these descriptions will be ignored herein.
Technical solution in order to better illustrate the present invention is first briefly described the principle of observation of magnetic domain method.
Using based on magneto-optical kerr microscope (MOKE) and magneto-optic thin film (MOIF) Lai Jinhang observation of magnetic domain in the present embodiment.Fig. 1 is magnetic
Light Ke Er microscope schematic diagram.Fig. 2 is magneto-optic thin film structural schematic diagram.As depicted in figs. 1 and 2, a branch of natural light is by being polarized
Device becomes linearly polarized light, and linearly polarized light interacts by MOIF, and with magneto-optic Bi-YIG layers in MOIF, so that linearly polarized light is inclined
Vibration face changes with faraday rotation angle.Light passes through in entire MOIF Bi-YIG layers of magneto-optic, encounters in MOIF and occurs instead after Al layers
It penetrates.Reflected light is again and after second of Faraday effect of Bi-YIG layers of magneto-optic generation, after compensator and analyzer, faraday
Corner is detected and is imaged, and records and saves finally by high-speed camera.Since MOIF magnetic domain is to vertical magnetic field
Very sensitive, magnetic flux leakage vertical component makes magnetized state in MOIF change.
Fig. 3 is magneto-optic thin film domain pattern illustraton of model under different situations.Wherein, Fig. 3 (a) is that magneto-optic is thin under no magnetic field conditions
Film domain pattern；Fig. 3 (b) is magneto-optic thin film domain model figure under no magnetic field conditions；Fig. 3 (c) is magneto-optic under magnetic field vertically upward
Thin film magnetic domains variation model figure；Fig. 3 (d) is magneto-optic thin film magnetic domain variation model figure vertically downward.As shown in Fig. 3 (a), without outer
Add magnetic field conditions, light and shade magnetic domain area equation in MOIF domain pattern, illustraton of model can be indicated with Fig. 3 (b).It is certain when applying
Vertically upward behind magnetic field, bright magnetic domain area expansion, dark magnetic domain area reduces, shown in illustraton of model such as Fig. 3 (c).On the contrary, when applying
Add centainly vertically downward behind magnetic field, dark magnetic domain area expansion, bright magnetic domain area reduces, shown in illustraton of model such as Fig. 3 (d).When
When MOIF is placed on ferrimagnet surface, the magnetic domain on ferrimagnet surface can generate magnetic flux leakage.The magnetic flux leakage vertical component makes
It obtains MOIF magnetized state to change, while daraf(reciprocal of farad) corner is changed.Due to using general view microscope, farad
Signal by analyzer when be averaged.Finally, light and dark image is sample different directions magnetic domain.Magnetic domain is adding magnetic outside
Off field, neticdomain wall moves, movement speed and pinning strength, internal stress size, anisotropy, dislocation density etc. inside because
Element is closely related, while being influenced by applied stress, temperature, bigoted magnetic field.Fig. 4 is magnetizing assembly block schematic illustration.
By taking highly oriented electrical sheet as an example, its magnetic domain figure outside difference plus under tensile stress and different magnetic field intensity is obtained respectively
Picture.Fig. 5 is the domain pattern of highly oriented electrical sheet under 0MPa stress different magnetic field intensity.Fig. 6 is 30.9MPa stress different magnetic field
The domain pattern of highly oriented electrical sheet under intensity.Fig. 7 is the magnetic domain of highly oriented electrical sheet under 61.9MPa stress different magnetic field intensity
Image.As shown in Figures 5 to 7, gray scale is darker for 180 degree magnetic domain, and brighter gray scale is -180 degree magnetic domain.Such as Fig. 5 (a) and 6
(a) shown in, when magnetic field strength is 177A/m, under 0MPa and 30.9MPa effect, all magnetic domains of electrical sheet orientation both facing to
180 degree direction；However, thering is very much -180 degree magnetic domain to occur, as shown in Fig. 7 (a) at 61.9MPa.When magnetic field strength drops to
25A/m, magnetic domain orientation are changed, and when stress is 61.9MPa, -180 degree magnetic domain is expanded, the contracting of 180 degree domain width
It is small, as shown in Fig. 7 (b)；Under 30.9MPa stress, a large amount of -180 degree magnetic domain occurs, as shown in Fig. 6 (b)；However, being in stress
In the case where zero, all magnetic domains are still both facing to 180 degree direction, as shown in Fig. 5 (b).When magnetic field drops to 0A/m situation,
When stress is 0, a large amount of -180 degree magnetic domain occurs, as shown in Fig. 5 (c)；In 30.9MPa and 61.9MPa, -180 degree magnetic domain
It is all expanded, 180 degree domain width reduces；This phenomenon shows that metal component internal stress increases, and makes magnetic in magnetic history
Magnetic field strength required for farmland is all flipped increases.
As it can be seen that the present invention is exactly this right by extracting there are corresponding relationship between magnetic domain dynamic behaviour and application
Characteristic value in should being related to establishes the relational model between characteristic value and stress, so that stress be quantitatively evaluated.Fig. 8 is the present invention
The specific embodiment flow chart of stress evaluation method based on domain motion threshold field.As shown in figure 8, the present invention is based on magnetic
The stress evaluation method in farmland movement threshold magnetic field the following steps are included:
S801: initialization application parameter value and change of magnetic field strength range:
The stress parameters collection φ={ σ simulated needed for feeromagnetic metal component determine according to actual needs1,σ2…,σKAnd magnetic
Field intensity variation range [- Hmax,Hmax], wherein K indicates stress parameters quantity, HmaxIndicate maximum field strength.
S802: setting stress parameters serial number k=1.
S803: it obtains and normalizes magnetic domain quantized value under different magnetic field intensity:
By magnetic field strength H from-HmaxIt is gradually increased to Hmax, then gradually reduce to-Hmax, obtain stress parameters σkIt is lower each
The corresponding normalization magnetic domain quantized value S of magnetic field strength HNom.Fig. 9 is the acquisition flow chart for normalizing magnetic domain quantized value.Such as Fig. 9 institute
Show, the corresponding normalization magnetic domain quantized value S of each magnetic field strength HNomAcquisition methods the following steps are included:
S901: domain pattern is obtained:
Obtain stress parameters σkWith the domain pattern under magnetic field strength H.
S902: domain pattern denoising:
Denoising is carried out to the domain pattern obtained in step S901.Image denoising algorithm is the normal of field of image processing
With technological means, can according to need the specific Image denoising algorithm of selection, in the present embodiment using wavelet filteration method come into
Row denoising.Figure 10 is to carry out domain pattern pretreatment exemplary diagram using wavelet filteration method in the present embodiment.
S903: domain pattern binaryzation:
According to before to the explanation of domain pattern it is found that gray scale is darker for 180 degree magnetic domain, gray scale in domain pattern
Brighter is -180 degree magnetic domain, and the width of 180 degree magnetic domain and -180 degree magnetic domain can change with the variation in stress and magnetic field,
Therefore the present invention quantifies magnetic domain using the area of 180 degree magnetic domain and -180 degree magnetic domain.For the ease of quantization, first to magnetic
Farmland image carries out binaryzation, represents 180 degree magnetic domain with 0 representative -180 degree magnetic domain, 1.Image binaryzation is also field of image processing
Common technology means, can according to need selection specific algorithm.Due to the even property of uneven illumination, domain pattern brightness irregularities,
The Image binarizing algorithm that local auto-adaptive threshold value is preferably based on by comparing, in the present embodiment to carry out two-value to domain pattern
Change.Figure 11 is that domain pattern binaryzation exemplary diagram is adopted in the present embodiment.
S904: magnetic domain quantized value is calculated:
Magnetic domain qualitative description level is also rested on to magnetic domain description in the industry at present.Also rare research is quantified to magnetic domain.Base
In ferromagnetic material 180 degree to -180 degree magnetic domain wall moving, the present invention quantifies its moving characteristic using following formula:
Wherein, Δ S indicates magnetic domain quantized value,WithRespectively represent all 180 degrees and -180 degree magnetic domain area.?
Under demagnetized state, 180 degree and -180 degree magnetic domain area equation, Δ S are equal to zero.After applying externally-applied magnetic field, neticdomain wall is moved
Dynamic, corresponding magnetic domain area changes, and the value of Δ S changes therewith.
As it can be seen that needing to obtain all 180 degrees and -180 degree magnetic domain area first when calculating magnetic domain quantized value Δ S
WithIts calculation method are as follows: to the binaryzation domain pattern that step S806 is obtained, count 0 and 1 in binaryzation domain pattern
Pixel quantity is denoted as n respectively-180°And n180°, then 180 degree magnetic domain area180 degree magnetic domain areaS indicates the area of single pixel point in domain pattern.Obvious s is determined by the resolution ratio of domain pattern
's.
S905: magnetic domain score normalization:
For the ease of subsequent processing, magnetic domain quantized value is normalized using following formula, obtains normalization magnetic domain amount
Change value SNom:
After normalization, SNomValue between -1 to+1.Work as SNomWhen value is -1, all magnetic domains direction -180 degree side is indicated
To；Work as SNomWhen value is+1, indicate all magnetic domains towards 180 degree direction.
S804: fitting SNom- H curve:
According to step S803 it is found that since ferromagnetic material magnetization is a magnetic hysteresis process, magnetic field strength of the invention
First from-HmaxChange to Hmax, then change back-H againmax, remember that there are N number of magnetic field strengths in unidirectional change procedure, amount to 2N magnetic
Field intensity value, each available normalization magnetic domain quantized value of magnetic field strength, to obtain 2N normalization magnetic domain quantization
Value.So according to this 2N to field strength values and normalization magnetic domain quantized value, so that it may which fitting obtains current stress parameters σkUnder
The S that normalization magnetic domain quantized value changes with field strength valuesNom- H curve.
Figure 12 is SNom- H curve exemplary diagram.As shown in figure 12, in SNomIn-H curve, there are 4 to enable SNomIt is 1 or -1
Threshold limit value magnetic field Hth1、Hth2、Hth3、Hth4, wherein Hth1And Hth4Positioned at 1st quadrant, Hth2And Hth3Positioned at third quadrant.Under
Drop works as H along (during magnetic field strength becomes smaller)th2< H < Hth1When, neticdomain wall moves, H > Hth1(H < Hth2) when, own
Neticdomain wall is both facing to 180 degree (- 180 degree direction).Rising edge (during magnetic field strength becomes larger), work as Hth3< H < Hth4When, magnetic
Domain wall moves, H > Hth4(H < Hth3) when, all neticdomain walls are both facing to 180 degree (- 180 degree direction).It is found that this 4 are faced
Boundary threshold field Hth1、Hth2、Hth3、Hth4It is exactly corresponding threshold field under current stress parameters.Therefore according to SNom- H curve obtains
To current stress parameters σkLower 4 orders normalize magnetic domain quantized value SNomFor 1 or -1 threshold limit value magnetic field Hth1(k)、Hth2(k)、
Hth3(k)、Hth4(k)。
S805: judge whether otherwise k < K enters step S807 if so, entering step S806.
S806: k=k+1, return step S803 are enabled.
S807: feature extraction:
According to step S802 to step S806 it is found that for each stress parameters σk, S can be obtainedNom- H curve,
There are 4 threshold fields for exactly each stress parameters.Figure 13 is S under different stressNom- H curve and threshold field and stress close
It is exemplary diagram.It has been investigated that 4 threshold fields and stress value all have the linear dependence of height, Figure 13 (b) is illustrated
SNom- H curve failing edge first quartile threshold field (Hth1) and stress between linear relationship.It therefore can be according to K stress
Parameter σkCorresponding threshold field carries out linear fit and obtains threshold field expression formula:
Hth1=a1σ+b1
Hth2=a2σ+b2
Hth3=a3σ+b3
Hth4=a4σ+b4
Wherein, am、bmIt is the linear dimensions in threshold field expression formula respectively, m=1,2,3,4.
S808: stress evaluation:
When carrying out stress evaluation to feeromagnetic metal component, S is obtained using mode identical with step S803 firstNom-H
Curve obtains 4 threshold fields, substitutes into the threshold field expression formula that step S807 is fitted, can be calculated 4 and answer
Force value σ (1), σ (2), σ (3) and σ (4), 4 stress value σ (1), σ (2), σ (3) and σ (4) are averaged, can be obtained final
Stress value σ:
Embodiment
Technical effect in order to better illustrate the present invention, using the stress based on domain motion threshold field in the present invention
The Evaluated effect of appraisal procedure and the stress evaluation method based on traditional macro magnetic characteristic characteristic parameter carries out Experimental comparison.Tradition
Macroscopical magnetic characteristic characteristic parameter includes remanent magnetism, magnetic hystersis loss, coercivity.Sample is the highly oriented silicon steel of Baosteel, ruler in the present embodiment
It is very little: 300mm × 30mm × 0.27mm (length × width × height), experiment parameter are as follows: excitation waveform: triangular wave；Driving frequency:
0.01Hz；Magnetic field amplitude: 1000A/m.It is respectively as follows: using the obtained threshold field expression formula of the present invention
Hth1=3.93* σ+19.18
Hth2=-3.93* σ -78.25
Hth3=-3.93* σ -21.50
Hth4=3.93* σ+77.40
Since the unit of characteristic parameter is different, need first to be normalized, normalization process can be stated are as follows: no
With the value under stress divided by maximum value.Figure 14 is the relationship contrast curve chart between different characteristic parameter and stress.Such as Figure 14 institute
Show, is not linear relationship between traditional macro magnetic characteristic characteristic parameter and stress, and threshold field of the present invention (with
Threshold field Hth1For) and stress between there are linear relationships.The threshold field that analysis proposes in terms of three is corresponded to below
Power detects advantage: the different ranges of stress, and each magnetic characteristic parameter changes with rate of stressing, stress mornitoring effect, minimal stress
Evaluated effect discuss.
Table 1 is the rate (unit: percentage/MPa) that different stage of stress stress change with parameter of magnetic characteristic.
Table 1
From table 1 it is known that threshold field is relatively uniform in the variation of different stage of stress with stress variation, all 1.44%
Every megapascal, sensitivity are higher；Coercivity all changes relatively slowly in 0-61.9MPa range, and sensitivity is very poor；Remanent magnetism is in 0-
Quickly, sensitivity is very high for rate of change within the scope of 12.3MPa, reaches 5% every megapascal, within the scope of 12.3MPa-24.7MPa
Changing rate of change reduces fastly, and sensitivity is general, and in the 24.7MPa-61.9MPa stage, rate of change becomes very slowly, sensitive
Difference；Magnetic hystersis loss is all relatively slow in entire stage of stress rate of change, sensitive lower.
For the detection effect that comparison different characteristic parameter changes stress and minimal stress, definition is greater than 1% when change rate
Every megapascal is that detection effect is fine；When rate of change be greater than 0.5% and when less than 1% every megapascal it is general for detection effect；
When rate of change is poor for detection effect less than 0.5%.Table 2 is characterized the detection effect pair of parameter stress and minimal stress variation
Compare result.It is learnt from table 2, when stress is lesser, the detection that remanent magnetism and threshold field change stress and minimal stress is all
With very high sensitivity, remanent magnetism and magnetic hystersis loss detection effect are poor；After stress becomes larger, threshold field detection effect is still
Very well, but coercivity, remanent magnetism, magnetic hystersis loss detection effect are all poor.
Table 2
It to sum up analyzes, compared to coercivity, remanent magnetism, magnetic hystersis loss tradition parameter of magnetic characteristic, the present invention proposes threshold field
There is good detection effect to stress and minimal stress detection.
Although the illustrative specific embodiment of the present invention is described above, in order to the technology of the art
Personnel understand the present invention, it should be apparent that the present invention is not limited to the range of specific embodiment, to the common skill of the art
For art personnel, if various change the attached claims limit and determine the spirit and scope of the present invention in, these
Variation is it will be apparent that all utilize the innovation and creation of present inventive concept in the column of protection.
Claims (2)
1. a kind of stress evaluation method based on domain motion threshold field, which comprises the following steps:
S1: the stress parameters collection φ={ σ simulated needed for feeromagnetic metal component determine according to actual needs1,σ2…,σKAnd magnetic
Field intensity variation range [- Hmax,Hmax], wherein K indicates stress parameters quantity, HmaxIndicate maximum field strength；
S2: setting stress parameters serial number k=1；
S3: by magnetic field strength H from-HmaxIt is gradually increased to Hmax, then gradually reduce to-Hmax, obtain stress parameters σkUnder each magnetic
The corresponding normalization magnetic domain quantized value S of field intensity HNom, the corresponding normalization magnetic domain quantized value S of each magnetic field strength HNomAcquisition
Method the following steps are included:
S3.1: feeromagnetic metal component is obtained in stress parameters σkWith the domain pattern under magnetic field strength H；
S3.2: denoising is carried out to domain pattern；
S3.3: binaryzation is carried out to domain pattern, 180 degree magnetic domain is represented with 0 representative -180 degree magnetic domain, 1；
S3.4: to binaryzation domain pattern, in binaryzation domain pattern 0 and 1 pixel quantity is counted, is denoted as n respectively-180°With
n180°, calculate 180 degree magnetic domain areaWith -180 degree magnetic domain areaS indicates magnetic domain figure
The area of single pixel point as in；Then magnetic domain quantized value Δ S is calculated according to the following formula:
S3.5: being normalized magnetic domain quantized value using following formula, obtains normalization magnetic domain quantized value SNom:
S4: according to the corresponding normalization magnetic domain quantized value S of magnetic field strength H each in step S3Nom, it is fitted and obtains current stress ginseng
Number σkThe S that lower normalization magnetic domain quantized value changes with field strength valuesNom- H curve；According to SNom- H curve obtains 4 and enables normalizing
Change magnetic domain quantized value SNomFor 1 or -1 threshold field Hth1(k)、Hth2(k)、Hth3(k)、Hth4(k)；
S5: if k < K, k=k+1, return step S3 is enabled otherwise to enter step S6；
S6: according to K stress parameters σkCorresponding 4 threshold fields carry out linear fit and obtain threshold field expression formula:
Hth1=a1σ+b1
Hth2=a2σ+b2
Hth3=a3σ+b3
Hth4=a4σ+b4
Wherein, am、bmIt is the linear dimensions in threshold field expression formula respectively, m=1,2,3,4；
S7: when carrying out stress evaluation to feeromagnetic metal component, S is obtained using with the same way in step S4 firstNom- H is bent
Line obtains 4 threshold fields, then substitutes into the threshold field expression formula of step S6,4 stress value σ (1), σ are calculated
(2), 4 stress value σ (1), σ (2), σ (3) and σ (4) are averagely obtained final stress value σ by σ (3) and σ (4).
2. stress evaluation method according to claim 1, which is characterized in that in the step S3.3, to domain pattern into
Row binaryzation uses the Image binarizing algorithm based on local auto-adaptive threshold value.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101266286A (en) * | 2008-03-26 | 2008-09-17 | 中国科学院上海光学精密机械研究所 | Magnetic domain observation device |
| WO2012049538A1 (en) * | 2010-10-12 | 2012-04-19 | Indian Institute Of Technology Kanpur | Systems and methods for imaging characteristics of a sample and for identifying regions of damage in the sample |
| CN102520058A (en) * | 2011-10-13 | 2012-06-27 | 北京工业大学 | Metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization |
| JP5699883B2 (en) * | 2011-09-26 | 2015-04-15 | トヨタ自動車株式会社 | Internal strain identification method for electrical steel sheets |
| CN104764798A (en) * | 2015-03-26 | 2015-07-08 | 电子科技大学 | Visual magnetic flux leakage detection device |
| CN105372324A (en) * | 2015-12-07 | 2016-03-02 | 电子科技大学 | Defect detection method based on magnetooptical imaging |
-
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- 2016-09-29 CN CN201610861624.1A patent/CN106442708B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101266286A (en) * | 2008-03-26 | 2008-09-17 | 中国科学院上海光学精密机械研究所 | Magnetic domain observation device |
| WO2012049538A1 (en) * | 2010-10-12 | 2012-04-19 | Indian Institute Of Technology Kanpur | Systems and methods for imaging characteristics of a sample and for identifying regions of damage in the sample |
| JP5699883B2 (en) * | 2011-09-26 | 2015-04-15 | トヨタ自動車株式会社 | Internal strain identification method for electrical steel sheets |
| CN102520058A (en) * | 2011-10-13 | 2012-06-27 | 北京工业大学 | Metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization |
| CN104764798A (en) * | 2015-03-26 | 2015-07-08 | 电子科技大学 | Visual magnetic flux leakage detection device |
| CN105372324A (en) * | 2015-12-07 | 2016-03-02 | 电子科技大学 | Defect detection method based on magnetooptical imaging |
Non-Patent Citations (1)
| Title |
|---|
| 磁畴的观察方法;宋红章 等;《材料导报》;20100910;第24卷(第9期);第106-111页 * |
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