CN110412119A - A kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference - Google Patents
A kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference Download PDFInfo
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- CN110412119A CN110412119A CN201910472688.6A CN201910472688A CN110412119A CN 110412119 A CN110412119 A CN 110412119A CN 201910472688 A CN201910472688 A CN 201910472688A CN 110412119 A CN110412119 A CN 110412119A
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- optical fiber
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- magnetic core
- magnetic flux
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- 230000005291 magnetic effect Effects 0.000 title claims abstract description 74
- 230000004907 flux Effects 0.000 title claims abstract description 28
- 238000001514 detection method Methods 0.000 title claims abstract description 17
- 239000013307 optical fiber Substances 0.000 claims abstract description 39
- 239000011553 magnetic fluid Substances 0.000 claims abstract description 14
- 230000007547 defect Effects 0.000 claims abstract description 13
- 239000000835 fiber Substances 0.000 claims abstract description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 239000010949 copper Substances 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 230000000644 propagated effect Effects 0.000 claims abstract description 5
- 230000002950 deficient Effects 0.000 claims description 3
- 239000003302 ferromagnetic material Substances 0.000 claims description 3
- 230000008878 coupling Effects 0.000 claims 1
- 238000010168 coupling process Methods 0.000 claims 1
- 238000005859 coupling reaction Methods 0.000 claims 1
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 abstract description 4
- 230000003287 optical effect Effects 0.000 description 11
- 230000002500 effect on skin Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000005622 photoelectricity Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 206010007247 Carbuncle Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005672 electromagnetic field Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/83—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
- G01N2021/458—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods using interferential sensor, e.g. sensor fibre, possibly on optical waveguide
Abstract
The invention discloses a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference, it is characterised in that: by wideband light source, optoisolator, fiber coupler, FC optical fiber connector, novel magnetic core, photodetector, amplifier, oscillograph, copper enameled wire, the optical fiber across magnetic core, magnetic fluid composition；Magnetic fluid is coated on the optical fiber of magnetic core, the light that wideband light source issues is transferred to optoisolator by optical fiber and enters fiber coupler, two column light waves being divided into afterwards clockwise and counterclockwise are propagated through FC optical fiber connector respectively, by the optical fiber for passing through novel magnetic core, two column light waves generate interference in photodetector surfaces, and interference signal, which by photodetector is converted to electric signal and passes through again, is shown to oscillograph for waveform after amplifier.The present invention has the characteristics that simple, convenient carrying, high sensitivity, can efficiently control the sensitivity and cost of detection using the various defects of measurement ferrimagnet.
Description
Technical field
The present invention provides a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference belongs to Electromagnetic Testing Technology neck
Domain.
Background technique
White light interference is using noncoherent wideband light source, although coherence length is very short, its advantages are that have one
A apparent zero order interference fringe, the corresponding position of this striped is exactly zero optical path difference position, provides the reference of measurement
Point.
Low frequency Magnetic Flux Leakage Inspecting is a kind of method of electromagnetic nondestructive, is contacted without the surface with examined workpiece, to corrosion
Property damage have higher detectivity.Low frequency Magnetic Flux Leakage Inspecting technology is since 1950, and driving frequency is usually 1 KHz-
500KHz is influenced by skin effect, and the penetration depth of Magnetic Flux Leakage Inspecting is limited significantly, therefore Magnetic Flux Leakage Inspecting is usually used in gold
Metal surface and near surface detection.Low frequency leakage field overcomes the influence of skin effect by reducing frequency, effectively improves detection depth 30
Times or more.
Under lower state after optical fiber sagnac interferometer, two column light waves of formation exist light source in different directions
It is propagated in same root light, does not generate optical path difference, optical fibre refractivity is changed by the variation in magnetic field, may be implemented to ferromagnetic
The measurement of the defect of property material.
Based on the above background, research and develop it is a kind of can be not high to surface requirements, it is therefore desirable to have the quick, light of certain lift-off, spirit
The relatively high lossless detection method of sensitivity is the emphasis of current research, is conducive to the failure for preferably preventing special equipment.
Summary of the invention
The purpose of the present invention is to provide a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference.The present invention has
Easy to carry, structure is simple, easily operated, and susceptibility is high, and can be applied to the defect of measurement ferrimagnet, there are situations.
The invention is realized by the following technical scheme: a kind of low frequency Magnetic Flux Leakage Inspecting based on white light interference, which is detected a flaw, is
System, by wideband light source (1), optoisolator (2), fiber coupler (3), FC optical fiber connector (4), novel magnetic core (5), photoelectricity
Detector (6), amplifier (7), oscillograph (8), copper enameled wire (9), the optical fiber (10) across magnetic core, magnetic fluid (11) composition；
Magnetic fluid (11) are coated on the optical fiber (10) of magnetic core it is characterized by: passing through, the light that wideband light source (1) issues passes through optical fiber
Optoisolator (2) are transferred into fiber coupler (3), after be divided into two column light waves difference clockwise and counterclockwise
It is propagated through FC optical fiber connector (4), by passing through the optical fiber of novel magnetic core (5), two column light waves are on photodetector (6) surface
Generate interference, interference signal, which by photodetector (6) is converted to electric signal and passes through waveform to be shown to after amplifier (7) again, to be shown
Wave device (8).If ferrimagnet is defective, interference fringe changes, then the interference signal of photodetector (6) occurs
Change, the signal on corresponding oscillograph (8) will also change；Workpiece, defect part magnetic conductivity becomes smaller, and causes magnetic flux not
It can be uniformly distributed, remaining magnetic field is coated with the optical fiber surrounding magnetic field of magnetic fluid (8) then outside workpiece by becoming magnetic flux leakage
It is influenced to change by magnetic flux leakage, the arrangement of magnetic fluid (8) changes, so as to cause the optical fiber (10) for passing through novel magnetic core
The effective refractive index on surface changes, and interference fringe is caused to change, by oscillograph (8) reading can with change perceived,
And then detect the defect of ferromagnetic materials surface.
The novel magnetic core (5), inner radii 55mm, magnet width are 60mm.
The line footpath of affiliated copper enameled wire (9) is 0.5mm, and number of turns is 400 circles.
The working principle of the invention is: the interference pattern based on the interference of optical fiber Sagnac, and the light issued from light source passes through
Two-beam clockwise and anticlockwise is divided by coupler after optoisolator, coupler is finally again passed by and reaches optical detector.
The excitation coil of copper enameled wire composition excites one alternating electromagnetic field of generation will at lower frequency (generally 1Hz-100Hz)
Examined workpiece is magnetized.After examined workpiece obtains magnetism, if do not damaged, the magnetic line of force is uniformly distributed in workpiece and magnetic
Field is not revealed, and leakage magnetic flux is about zero at this time.When haveing damage, such as above-mentioned analysis, workpiece, defect part magnetic conductivity becomes smaller, and causes
Prevent magnetic flux from being uniformly distributed, and magnetic field cannot be all by the part, there are three paths in magnetic field at this time, first is that from defect
Recess penetrate, second is that still penetrating from workpiece, remaining magnetic field then passes through outside workpiece, leaks out, and becomes leakage field
, magnetic flux leakage changes with the change of damage external form and size.Optical fiber ambient magnetic field environment changes, the row of magnetic fluid
Cloth changes, and the effective refractive index so as to cause fiber optic interferometric ring surface changes, and interference fringe is caused to change.
So the typical information of defect can be obtained by detecting magnetic leakage signal.
It is located at the obtained light intensity in surface of PD detector are as follows:
Wherein:It is the complex amplitude that PD detects electric field strength；α is that coupler is attached
Add loss, defines α=total Output optical power/total input optical power；k1、k2For real constant (paths damage clockwise, counterclockwise
Consume coefficient)；τ is the time delay of optical path clockwise, counterclockwise.
It usually can approximately think that the loss of optical path optical fiber clockwise and anticlockwise is close, i.e. k1=k2=k, then above-mentioned formula
It can abbreviation are as follows:
Wherein:In formula, n0For the refractive index of fiber cores；ΔS1、ΔS2Point
The change in optical path length that Biao Shi not be influenced and occur by external carbuncle from the two column light beams that coupler comes out.
Light propagates passed by light path S in a fiber are as follows: S=n0L.Light caused by deformation occurs under external influence for optical fiber
Journey changes are as follows:
Δ S=n0ΔL+LΔn0
Wherein Δ L is the change of fiber lengths, Δ n0For the variation of optical fibre refractivity.The change of fiber lengths are as follows:
Δ L=L ε
ε is the strain value of optical fiber in formula.
So zero order fringe has maximum amplitude in the center of interference fringe when in the not defective situation of ferrimagnet,
Corresponding to optical path clockwise and optical path phase counterclockwise etc..When existing defects lead to change in optical path length, white light interference center striped
Position will move.
The beneficial effects of the present invention are: using the interference of optical fiber Sagnac and novel magnetic core as primary structure, with white light interference
Based on, it is not necessarily to permanent-magnet-field, alleviates weight of equipment and manipulation strength, it is easy to carry.It can identify that defect is to be located to be detected
The bottom or top of test specimen improve detection accuracy, and low to tested surface requirements, can efficiently control detection spirit
Sensitivity and cost, flexibility are relatively high.
Detailed description of the invention
Fig. 1 is a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system overall schematic based on white light interference；
Fig. 2 is novel magnetic core front view；
Fig. 3 is novel magnetic core right view；
Specific embodiment
Such as Fig. 1, a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference, by wideband light source (1), optoisolator
(2), fiber coupler (3), FC optical fiber connector (4), novel magnetic core (5), photodetector (6), amplifier (7), oscillography
Device (8), copper enameled wire (9), the optical fiber (10) across magnetic core, magnetic fluid (11) composition；It is characterized by: passing through the light of magnetic core
Magnetic fluid (11) are coated on fine (10), the light that wideband light source (1) issues is transferred to optoisolator (2) into light by optical fiber
Fine coupler (3), after be divided into two column light waves clockwise and counterclockwise and propagated respectively through FC optical fiber connector (4), lead to
The optical fiber across novel magnetic core (5) is crossed, two column light waves generate interference on photodetector (6) surface, and interference signal is visited by photoelectricity
It surveys device (6) and is converted to electric signal and passes through again and waveform is shown to oscillograph (8) after amplifier (7).If ferrimagnet has scarce
It falls into, interference fringe changes, then the interference signal of photodetector (6) changes, the letter on corresponding oscillograph (8)
It number will also change；Workpiece, defect part magnetic conductivity becomes smaller, and causes magnetic flux that cannot be uniformly distributed, remaining magnetic field then from
Workpiece is outer by becoming magnetic flux leakage, and the optical fiber surrounding magnetic field coated with magnetic fluid (8) is influenced to change by magnetic flux leakage, magnetic current
The arrangement of body (8) changes, and the effective refractive index so as to cause optical fiber (10) surface for passing through novel magnetic core changes,
Interference fringe is caused to change, can be with change perceived by oscillograph (8) reading, and then detect lacking for ferromagnetic materials surface
It falls into.
It is illustrated in figure 2 a kind of novel magnetic core schematic diagram of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference, magnetic
Core central angle is 270 °, inner radii 55mm, and internal-and external diameter difference is 10mm.
As shown in figure 3, novel magnetic core width is 60mm.
Claims (3)
1. a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference, by wideband light source (1), optoisolator (2), optical fiber coupling
Clutch (3), FC optical fiber connector (4), novel magnetic core (5), photodetector (6), amplifier (7), oscillograph (8), copper enamel-cover
Line (9), the optical fiber (10) across magnetic core, magnetic fluid (11) composition；It is characterized by: being coated on the optical fiber (10) of magnetic core
Magnetic fluid (11), the light that wideband light source (1) issues are transferred to optoisolator (2) by optical fiber and enter fiber coupler (3), afterwards quilt
Two column light waves being divided into clockwise and counterclockwise are propagated through FC optical fiber connector (4) respectively, by passing through novel magnetic core (5)
Optical fiber, two column light waves generate interference on photodetector (6) surface, and interference signal is converted to telecommunications by photodetector (6)
Number again by the way that waveform is shown to oscillograph (8) after amplifier (7).If ferrimagnet is defective, interference fringe becomes
Change, then the interference signal of photodetector (6) changes, and the signal on corresponding oscillograph (8) will also change；Workpiece
Defect part magnetic conductivity becomes smaller, and causes magnetic flux that cannot be uniformly distributed, remaining magnetic field then outside workpiece by become magnetic flux leakage,
Optical fiber surrounding magnetic field coated with magnetic fluid (8) is influenced to change by magnetic flux leakage, and the arrangement of magnetic fluid (8) changes, from
And the effective refractive index across optical fiber (10) surface of novel magnetic core is caused to change, cause interference fringe to change, leads to
Crossing oscillograph (8) reading can be with change perceived, and then detects the defect of ferromagnetic materials surface.
2. a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference according to claim 1, it is characterised in that: new
Type magnetic core (5), inner radii 55mm, magnet width are 60mm.
3. a kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference according to claim 1, it is characterised in that: copper
The line footpath of enameled wire (9) is 0.5mm, and number of turns is 400 circles.
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| CN201910472688.6A CN110412119A (en) | 2019-05-31 | 2019-05-31 | A kind of low frequency Magnetic Flux Leakage Inspecting fault detection system based on white light interference |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102352963A (en) * | 2011-10-09 | 2012-02-15 | 中国计量学院 | Mixing interference distributed optical fiber-based leakage detection device for underwater long-distance pipeline |
| CN105353030A (en) * | 2015-12-08 | 2016-02-24 | 中国计量学院 | Low-frequency electromagnetism-based defect detecting device |
| CN107632060A (en) * | 2017-09-19 | 2018-01-26 | 电子科技大学 | A kind of defect inspection device based on fibre optic magnetic field sensing |
| CN108982659A (en) * | 2018-10-08 | 2018-12-11 | 中国计量大学 | A kind of full-automatic defect detecting device based on low frequency electromagnetic |
| CN109358110A (en) * | 2018-11-28 | 2019-02-19 | 中国计量大学 | A kind of array electromagnetism various dimensions detection system for the imaging of steel plate internal flaw |
| CN109406103A (en) * | 2018-12-03 | 2019-03-01 | 中国计量大学 | A kind of optical cable non-destructive tests and current sensor device based on white light interference |
-
2019
- 2019-05-31 CN CN201910472688.6A patent/CN110412119A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102352963A (en) * | 2011-10-09 | 2012-02-15 | 中国计量学院 | Mixing interference distributed optical fiber-based leakage detection device for underwater long-distance pipeline |
| CN105353030A (en) * | 2015-12-08 | 2016-02-24 | 中国计量学院 | Low-frequency electromagnetism-based defect detecting device |
| CN107632060A (en) * | 2017-09-19 | 2018-01-26 | 电子科技大学 | A kind of defect inspection device based on fibre optic magnetic field sensing |
| CN108982659A (en) * | 2018-10-08 | 2018-12-11 | 中国计量大学 | A kind of full-automatic defect detecting device based on low frequency electromagnetic |
| CN109358110A (en) * | 2018-11-28 | 2019-02-19 | 中国计量大学 | A kind of array electromagnetism various dimensions detection system for the imaging of steel plate internal flaw |
| CN109406103A (en) * | 2018-12-03 | 2019-03-01 | 中国计量大学 | A kind of optical cable non-destructive tests and current sensor device based on white light interference |
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