CN109856232A - A kind of leakage field lossless detection device based on fiber Bragg grating F-P chamber magnetic field sensor - Google Patents
A kind of leakage field lossless detection device based on fiber Bragg grating F-P chamber magnetic field sensor Download PDFInfo
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- CN109856232A CN109856232A CN201910318008.5A CN201910318008A CN109856232A CN 109856232 A CN109856232 A CN 109856232A CN 201910318008 A CN201910318008 A CN 201910318008A CN 109856232 A CN109856232 A CN 109856232A
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Abstract
The invention discloses a kind of leakage field lossless detection devices based on fiber Bragg grating F-P chamber magnetic field sensor.Include power module, wideband light source, coupler, fiber Bragg grating F-P chamber magnetic field sensor, photodetector, data collecting card, magnetizing coil structure, computer, precision potentiator, single-chip microcontroller, liquid crystal display, key.Testee local magnetized to being saturated, in the presence of there is crack on its surface, that is, is generated magnetic flux leakage by magnetization configuration；Source emissioning light wave reaches the magnetic susceptibility structure of fiber Bragg grating F-P chamber by coupler, under leakage field field action, flex effect, which occurs, for magnetostriction pipe causes F-P cavity chamber length that can change, fiber F-P cavity reflecting interference signal spectrum characteristic is eventually led to change, reflecting interference signal with Magnetic Field is transformed into electric signal by photodetector through the delivery outlet of coupler, it is transferred to data collecting card and is converted into digital signal through A/D and be delivered to computer, computer is further processed and analyzes to flaw indication again, specifies defect characteristics.
Description
Technical field
The invention belongs to the technology of instrument and meter fields of contactless metal detection, and in particular to one kind is based on fiber grating F-
The Nondestructive detection with magnetic flux leakage technology of P chamber magnetic field sensor.
Background technique
Foreign countries are more early to the time of Magnetic Flux Leakage Inspecting technology expansion research, and 1933, Zuschlug was pointed out for the first time using magnetosensitive
Sensor detects the concept of magnetic flux leakage, but until nineteen forty-seven Hanstings just develops first generation defect and magnetic leakage flaw detection system
System, then society starts to recognize the authenticity and value of Magnetic Flux Leakage Inspecting technology.
1966, Shcherb-inin, Zatsepin calculated the nothing on pipeline external surface by establishing dipole model of magnetic
Limit for length's open-delta winding, the Soviet Union publish an article the magnetic flux leakage generated at quantitative analysis workpiece failure in same year, indicate in article
With endless magnetic dipole band, magnetic dipole line, magnetic dipole simulation testee spot defect in appearance, the seam to split, shallowly split
Trace.
High magnetic permeability and magnetic based on ferrimagnet reflect the edge always of the Magnetic Flux Leakage Inspecting principle on physical characteristic basis
With till now, but these applications are main or based on qualitative detection.
The prior art is established on existing Magnetic Flux Leakage Inspecting principle understanding basis namely the magnetic dispersion of defect is from mechanism
On say be by be detected magnetic conduction structure body magnetic conductivity determined.This causes existing flux-leakage detection method to be solved there is having
Engineering problem.
Fibre Optical Sensor is mainly using optical fiber itself as transmission medium, and light wave transmissions are as carrier, luminous energy transmission and modulation
Measured signal is demodulated, sensing sensitivity is very high.Compare with traditional sensing technology, the small light weight of fibre diameter, signal decaying
It is weaker, can be completed at the same time information transmission and sensing, due to its unique performance advantage, fibre optical sensor is very suitable for strong magnetic
, inflammable and explosive, heat-flash good fortune penetrates, detects under the abnormal environments such as high temperature and pressure.Therefore, optical fiber sensing technology receives extensive pass
Note can be applied to many fields, and sensing technology is pushed constantly to improve forward.So being described below under the theory state
Reform changeable device.
Summary of the invention
In view of the deficiencies of the prior art, the present invention is in new theory: the effect based on fiber Bragg grating F-P chamber magnetic field sensor
Under, the advantages of the method for non-destructive testing testee is reached using leakage field, and possesses high efficiency low energy consumption high-accuracy
The invention is realized by the following technical scheme: by power module (1), wideband light source (2), coupler (3), optical fiber light
Grid F-P cavity magnetic field sensor (4), photodetector (5), PCIe9757 data collecting card (6), magnetizing coil structure (7) calculate
Machine (8), precision potentiator (9), single-chip microcontroller (10), liquid crystal display (11), key (12) is it is characterized by: power module (1) is each
Part powers, and single-chip microcontroller (10) generates adjustable square wave and adjusts frequency by precision potentiator (9) adjusting amplitude, by key (12)
Rate, and shown on liquid crystal display (11), it is sent into magnetizing coil structure (7) and generates magnetic field, magnetize component to be measured, wideband light source (2)
Emit light wave and reaches fiber Bragg grating F-P chamber magnetic field sensor (4) by coupler (3), under the action of magnetic flux leakage, magnetostriction
Flex effect occurs for pipe, causes the chamber length of fiber F-P cavity that can change, eventually leads to fiber F-P cavity reflecting interference signal
Spectral characteristic changes, and the reflecting interference signal with Magnetic Field is by the delivery outlet end of coupler (3) via photoelectricity
Detector (5) is transformed into electric signal, is transferred to and is converted into digital signal through A/D in PCIe9757 data collecting card (6) and is delivered to
Computer (8), computer (8) is again further processed flaw indication, analyzes, judges, detects the spies such as the Dimension Types of defect
Property.
The material of the magnetizing coil structure (7) is iron silicon oxysome, and to be arc-shaped, subtended angle is 270 °, with a thickness of 2cm,
Radius is 10cm, length 7cm.
The working principle of the invention is: magnetic field has diffusion and aggregation properties, at the interface of medium, the diffusion in magnetic field
Follow the condition of continuity with aggregation transmitting: 1. tangential magnetic field intensity is equal；2. normal direction magnetic induction intensity is equal.That is:
In formula, e is perpendicular to the unit vector at interface, is directed toward medium 2 by medium 1；B1 (H1) and B2 (H2) is respectively medium 1
Magnetic induction intensity (magnetic field strength) in (magnetic conductivity is μ 1) and medium 2 (magnetic conductivity is μ 2), they are in medium 1 and 2 in
The angle of normal e is respectively α 1, α 2.It can be obtained by formula (1):
In formula (2), Bne(Hne) and Bnτ(Hnτ) respectively in the normal direction of medium n (n=1,2) intrinsic inductance (magnetic field strength)
Component and tangential component, also to obtain the final product:
Formula (3) constitutes magnetic refraction diffusion rule.The refractive deflection direction of magnetic is related with the magnetic permeability of incidence angle and medium.Magnetic field
Direction and medium side geometry constitute incident angle α1.Due to α1=0 ° or α1=90 ° of magnetic incidence angle is only in ideal medium
Occur under the conditions of the geometry of face, so in conjunction with 0 < α of actual magnetic ranges of incidence angles1< 90 ° are made following discussion to formula (3).
(1) work as μ2=μ1When, there is α2=α1, the line of magnetic induction directly passes through interface and do not reflect.At same magnetizing field H, by B
B known to=μ H2=B1, the two magnetic pressure is equal at this time, and in the case where being zero magnetic dispersion does not occur for magnetic pressure differential mutually.
(2) work as μ2≤μ1When, there is α2≤α1, μ2The line of magnetic induction reflects in medium, and is folded to normal n, forms magnetic flux by μ1
Medium is to μ2The Release and dispersion of medium.
At this point, due to B2=μ2H≤μ1H=B1, there is by μ1Medium is to μ2The magnetic pressure differential of medium will form by the former latter
Magnetic dispersion diffusion, work as μ1Medium is conducting magnetic component, μ2When medium is air, ultimately forms and let out from conducting magnetic component to the magnetic of air
Dew.Due to the interface in medium, the defect namely 0 < α of mutation1< 90 ° of conditions, so here it is existing defect magnetic air to let out
Leak principle and its corresponding flux-leakage detection method.
But in any case, because of μ2(μair=1) >=1, so
As it can be seen that due to μ2(μair=1) presence >=1 causes deflection leakage angle to have 90 ° of-α of maximum value2。
(3) it is analyzed by (1), (2), further, it is assumed that there are certain medium μ2→ 0 or μ2=0, then it can obtain:
Or
In this way, the fringence of the line of magnetic induction be more biased in normal and coincide with, extreme refraction the most serious occurs, causes
Final magnetic dispersion.At this point, in fiber Bragg grating F-P chamber magnetic field sensor: according to the spectral signature theoretical model of FBG F-P.
If the length L of fiber grating FBG11, reflection and transmission coefficient are respectively rg1、tg1；Fiber grating FBG2's
Length L2, reflection and transmission coefficient are respectively rg2、tg2；The a length of h of FBG F-P cavity.
Assuming that two fiber gratings are just the same, and enable reflection coefficient and refraction coefficient is respectively rg1=rg2=| rg|exp(i
фr), tg1=tg2=| tg|exp(iфt), wherein фr, фtIt is reflection phase shift coefficient and the transmission phase shift system of two gratings respectively
Number.When two gratings are designed to the grating of weak reflectivity, the reflection coefficient of weak reflectivity P-FFBG chamber can be from which further followed that
Are as follows:
rF-P(λ)≈rg(λ)【1+exp(iфF-P)】 (7)
WhereinFor the phase coefficient of FBG F-P cavity, wherein LF-P≈Lg+ h, Lg=(L1+L2)/2,rgFor optical grating reflection
Coefficient, λ are optical wavelength.
Chamber in fiber Bragg grating F-P chamber low-intensity magnetic field sensor is grown to change under magnetic fields, passes through demodulation F-P sensor
Chamber is long, and the detection of Weak magentic-field can be realized.Using Fringe-counting method processing spectral signal to which chamber long value be calculated.Interference
The output intensity expression formula of light are as follows:
Since the chirped fiber grating that uses has very low reflectivity (R < < 1) in design, above formula can be approximately:
IR=2R[1-cos (4 Π nh/ λ)] I0 (9)
In the case where the long h of chamber is constant, interference light output intensity is in approximate cosine with the distribution of wavelength, it is assumed that light source is desired light
Source, i.e. output intensity are uniformly distributed with wavelength, by formula (9) it can be seen that when wavelength is located at λminWhen, interference output light has minimum
Value；With should wavelength be located at λmaxWhen, interference output light has maximum
λmin,λmaxMeet respectively:
Assuming that m grades of interference output striped are respectively λ with corresponding wavelength at m+n grades of maximummAnd λm+n, then have:
The expression formula of the long h of F-P cavity chamber can be obtained by formula (10) and formula (11) are as follows:
Light source light strong point is free of in formula (12), is avoided light-intensity variation and is exported to the long influence of chamber, interference is solved
The peak wavelength accuracy of striped determines the long accuracy solved of chamber.Then can have computer calculate change of cavity length for
The detection of leakage field is to improve accuracy.
The beneficial effects of the present invention are: being aided with fiber grating using leakage field detection principle as detection method in design of the invention
Sensor, based on change of magnetic field strength and the functional relation of damage position and degree of impairment, to the damage of metal component into
Row non-destructive testing.It is able to achieve contact-free detection, and measuring accuracy is higher, there is very strong innovative and practical value, have good
Good application prospect.
Detailed description of the invention
Fig. 1 is the leakage field lossless detection device work flow diagram based on fiber Bragg grating F-P chamber magnetic field sensor.
Fig. 2 is based on fiber Bragg grating F-P chamber magnetic field sensor structural schematic diagram.
Specific embodiment
A kind of leakage field lossless detection device based on fiber Bragg grating F-P chamber magnetic field sensor, by power module (1), broadband light
Source (2), coupler (3), fiber Bragg grating F-P chamber magnetic field sensor (4), photodetector (5), PCIe9757 data collecting card
(6), magnetizing coil structure (7), computer (8), precision potentiator (9), single-chip microcontroller (10), liquid crystal display (11), key (12) its
Be characterized in that: power module (1) generates adjustable square wave and is adjusted by precision potentiator (9) for each section power supply, single-chip microcontroller (10)
Amplitude adjusts frequency by key (12), and shows on liquid crystal display (11), is sent into magnetizing coil structure (7) and generates magnetic field, magnetic
Change component to be measured, wideband light source (2) emits light wave and reaches fiber Bragg grating F-P chamber magnetic field sensor (4) by coupler (3),
Under the action of magnetic flux leakage, flex effect occurs for magnetostriction pipe, causes the chamber length of fiber F-P cavity that can change, eventually leads to
Fiber F-P cavity reflecting interference signal spectrum characteristic changes, and the reflecting interference signal with Magnetic Field is through overcoupling
The delivery outlet end of device (3) is transformed into electric signal via photodetector (5), is transferred to warp in PCIe9757 data collecting card (6)
A/D is converted into digital signal and is delivered to computer (8), and computer (8) is again further processed flaw indication, analyzes, judges, visits
Measure the characteristics such as the Dimension Types of defect.
Claims (5)
1. the leakage field lossless detection device based on fiber Bragg grating F-P chamber magnetic field sensor, by power module (1), wideband light source (2),
Coupler (3), fiber Bragg grating F-P chamber magnetic field sensor (4), photodetector (5), data collecting card (6), magnetizing coil structure
(7), computer (8), precision potentiator (9), single-chip microcontroller (10), liquid crystal display (11), key (12) composition；It is characterized by: electric
Source module (1) is each section power supply, and single-chip microcontroller (10) generates adjustable square wave by precision potentiator (9) adjusting amplitude, by pressing
Key (12) adjusts frequency, and shows on liquid crystal display (11), is sent into magnetizing coil structure (7) and generates magnetic field, magnetizes component to be measured,
The material of magnetizing coil structure (7) is iron silicon oxysome, and to be arc-shaped, subtended angle is 270 °, thickness range 0.5-2cm, radius model
It encloses for 5-10cm, length range 3-7cm, wideband light source (2) emits light wave and reaches fiber Bragg grating F-P chamber by coupler (3)
Magnetic field sensor (4), under the action of magnetic flux leakage, flex effect occurs for magnetostriction pipe, causes the chamber length of fiber F-P cavity that can send out
Changing eventually leads to fiber F-P cavity reflecting interference signal spectrum characteristic and changes, and the reflected light with Magnetic Field is dry
It relates to signal and is transformed into electric signal via photodetector (5) by the delivery outlet end of coupler (3), be transferred to data collecting card
(6) it is converted into digital signal through A/D in be delivered to computer (8), computer (8) is again further processed flaw indication, detection
The size and type of defect out.
2. the leakage field lossless detection device according to claim 1 based on fiber Bragg grating F-P chamber magnetic field sensor, feature exist
In: fiber Bragg grating F-P chamber magnetic field sensor (4) and component interval 1mm-2mm to be measured.
3. the leakage field lossless detection device according to claim 1 based on fiber Bragg grating F-P chamber magnetic field sensor, feature exist
In: the square wave frequency range that single-chip microcontroller (10) generates is 10HZ-1KHZ, and amplitude range is that 1V-3.3V is adjustable.
4. the leakage field lossless detection device according to claim 1 based on fiber Bragg grating F-P chamber magnetic field sensor, feature exist
It is MPS-3002L-3 in: power module (1) model, it is 0~2V that output voltage range, which is 0~30V, accuracy rating, exports electric current
Precision is 0.1A.
5. the leakage field lossless detection device according to claim 1 based on fiber Bragg grating F-P chamber magnetic field sensor, feature exist
In: data collecting card (6) connects as the data acquisition module in leakage magnetic detection device, 2.0 bus of data collecting card compatible with PCI
Mouth standard, can be realized high speed data transfer.
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