CN107884477A - A kind of acoustic emission detection system and detection method based on fiber-optic grating sensor - Google Patents
A kind of acoustic emission detection system and detection method based on fiber-optic grating sensor Download PDFInfo
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- CN107884477A CN107884477A CN201711079031.0A CN201711079031A CN107884477A CN 107884477 A CN107884477 A CN 107884477A CN 201711079031 A CN201711079031 A CN 201711079031A CN 107884477 A CN107884477 A CN 107884477A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor
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- G—PHYSICS
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Abstract
The invention provides a kind of acoustic emission detection system and detection method based on fiber-optic grating sensor, including tunable laser, fiber-optic grating sensor, photoelectric detection module, demodulation module and servo-drive system；The reflected light of fiber-optic grating sensor is converted to electric signal by photoelectric detection module, servo-drive system can adjust the wavelength of tunable laser emergent light according to the electric signal, so that the intensity of reflected light adjusts to the direction of target intensity value, the electric signal of the photoelectric detection module output is transferred to demodulation module, and the demodulation module determines acoustic emission signal according to the electric signal.
Description
Technical field
The present invention relates to sensor technical field, is sent out more specifically to a kind of sound based on fiber-optic grating sensor
Penetrate detecting system and detection method.
Background technology
Sound emission refers to the phenomenon of solid material energy production elastic wave of release storage in fracture.Due to various materials
The frequency range of caused acoustic emission signal is different, and the acoustic emission signal intensity when deformation of most of materials and fracture is very weak,
Human ear can not directly hear, therefore, it is necessary to can just be detected with sensitive electronic instrument.
Existing acoustic emission detection system detects sound emission letter caused by various materials using piezoceramic transducer mostly
Number.Although this acoustic emission detection system has, equipment is simple, be easily installed, can a wide range of interior application on site the advantages of,
But because the volume of piezoceramic transducer is larger, therefore, it can be only installed at the outside of testee such as transformer, and
The inside of testee can not be arranged on, can so cause piezoceramic transducer to believe sound emission caused by testee inside
Number detection sensitivity it is relatively low.
Based on this, a kind of acoustic emission detection system based on fiber-optic grating sensor is proposed in the prior art, such as Fig. 1 institutes
Show, including fiber-optic grating sensor 10, laser 11 and demodulating system 12, fiber-optic grating sensor 10 are arranged on monitored object
00 inside or surface, for detecting acoustic emission signal caused by monitored object 00, especially in structural damage or bear to rush
When hitting, in the presence of acoustic emission signal, the centre wavelength of the reflected light of fiber-optic grating sensor 10 can shift；
Laser 11 is used to provide light source for fiber-optic grating sensor 10, so that fiber-optic grating sensor 10 reflects the reflection of specific wavelength
Light；Demodulating system 12 is used for center wavelength shift amount and pair of center wavelength shift amount and acoustic emission signal according to reflected light
It should be related to, obtain acoustic emission signal caused by monitored object 00.
Due to fiber-optic grating sensor small volume, in light weight, therefore, the optical fiber with fiber-optic grating sensor can be set
In the inside of testee, to improve the sensitivity of detecting system.But due to laser 11 wavelength can with environment temperature,
The change of the factors such as stress variation, vibration and change, therefore can influence or limit acoustic emission detection system detection sensitivity and
Accuracy.
The content of the invention
The embodiments of the invention provide a kind of acoustic emission detection system and detection method based on fiber-optic grating sensor, profit
In improvement acoustic emission detection system detection sensitivity, accuracy and antijamming capability.
The embodiment of the present invention provides following technical scheme：
A kind of acoustic emission detection system based on fiber-optic grating sensor, including tunable laser, optical fiber grating sensing
Device, photoelectric detection module, demodulation module, wave filter and servo-drive system；
The tunable laser is used to provide light source for the fiber-optic grating sensor, so that the optical fiber grating sensing
The incident light of device is the light of specific wavelength in the light source；
The fiber-optic grating sensor is used for the acoustic emission signal for detecting monitored object, wherein, produced in monitored object
In the presence of raw acoustic emission signal, the centre wavelength of the reflected light of the fiber-optic grating sensor can shift；
The photoelectric detection module is used for the reflected light for detecting the fiber-optic grating sensor, and the reflected light is changed
For electric signal；
The servo-drive system is used to judge whether the intensity of the reflected light is target intensity value according to the electric signal, if
It is no, then the wavelength of the tunable laser emergent light is adjusted, so that the intensity of the reflected light is to the target intensity value
Direction adjusts；
The electric signal of the photoelectric detection module output is transferred to the demodulation module；
The demodulation module is used for the center wavelength shift amount or described anti-that the reflected light is determined according to the electric signal
Penetrate the intensity of light, and according to the intensity of the corresponding relation or the reflected light of the center wavelength shift amount and acoustic emission signal with
The corresponding relation of acoustic emission signal determines acoustic emission signal caused by the monitored object；
Wherein, the servo-drive system includes at least one amplifier, and the amplifier is used to control by negative-feedback signal
The tunable laser is inputted to adjust the wavelength of the tunable laser emergent light；
The wave filter is located on the negative-feedback signal path, and the wave filter is used to filter out in the electric signal
Frequency is higher than the signal of predeterminated frequency, to adjust the wavelength of the tunable laser emergent light.
The predeterminated frequency can be a × f, wherein, f is the low-limit frequency of the sound emission of desired detection, and a is less than 1,1/
2nd, 1/4,1/10,1/100 or 1/1000.
The detecting system can include control system, and the control system is used for the acoustic emission signal and reference number
According to being contrasted, to obtain the health degree value of the monitored object, the reference data exists including the monitored object
The test data of caused acoustic emission signal under different health degrees.
The servo-drive system, it can be used for the ripple of the intensity and the tunable laser emergent light according to the reflected light
Long corresponding relation is adjusted at least with the next item down：The wavelength, described of the target intensity value, the tunable laser emergent light
The positive-negative polarity of negative-feedback signal.
The servo-drive system, can be used for the wavelength by adjusting the tunable laser emergent light, obtain described in not
The intensity of the reflected light under the wavelength of same tunable laser emergent light.
The detecting system can include at least one temperature sensor；
The temperature sensor is used for the ambient temperature data for detecting the fiber-optic grating sensor；
The servo-drive system, for according to the ambient temperature data and temperature and the tunable laser wavelength
Corresponding relation is adjusted at least with the next item down：The wavelength, described negative of the target intensity value, the tunable laser emergent ray
The positive-negative polarity of feedback signal.
Grating in the fiber-optic grating sensor can be phase-shifted grating, chirp grating, chirp grating to, Fabry-
One of Paro interference-type fiber bragg grating sensor, overlapping grating or the grating that partly overlaps, cascaded fiber grating, sampling optical fiber grating or group
Close.
A kind of acoustic emission detection method based on fiber-optic grating sensor, including：
The acoustic emission signal of the monitored object of detection；
The reflected light of detection fiber grating sensor, and the reflected light is converted into electric signal, wherein being sent out in the sound
Penetrate in the presence of signal, the centre wavelength of the reflected light can shift；
Whether the intensity that the reflected light is judged according to the electric signal is target intensity value；
If it is not, then adjusting the intensity of the reflected light to the direction of the target intensity value, and the reflected light is changed
For electric signal, the change of the center wavelength shift amount or the intensity of reflected light of the reflected light is determined according to the electric signal,
And the intensity and acoustic emission signal of the corresponding relation or the reflected light according to the center wavelength shift amount and acoustic emission signal
Corresponding relation determine acoustic emission signal caused by the monitored object.
Preferably, in addition to：
On the path of negative-feedback signal, the signal that frequency in the electric signal is higher than predeterminated frequency is filtered out, with regulation
The wavelength of the tunable laser emergent light；
According to the regulation of the corresponding relation of the intensity of the reflected light and the wavelength of the tunable laser emergent light at least
With the next item down：The target intensity value, the wavelength of the tunable laser emergent light, the both positive and negative polarity of the negative-feedback signal
Property；
The acoustic emission signal is contrasted with reference data, to obtain the health degree value of the monitored object,
The reference data includes the test data of monitored object caused acoustic emission signal under different health degrees；
Judge whether the health degree value exceeds early warning value, if so, then alert.
In the acoustic emission detection system and detection method based on fiber-optic grating sensor that the embodiment of the present invention is provided, watch
Dress system can judge whether the intensity of reflected light is target intensity value according to the electric signal that photoelectric detection module exports, if it is not, then
The wavelength of tunable laser emergent light is adjusted, so that the intensity of reflected light adjusts to the direction of target intensity value, the photoelectricity
The electric signal of detecting module output is transferred to demodulation module, and demodulation module determines that the centre wavelength of reflected light is inclined according to electric signal
The intensity of shifting amount or the reflected light, it is corresponding with acoustic emission signal according to the intensity of center wavelength shift amount or the reflected light
Relation determines acoustic emission signal caused by monitored object, by servo-drive system to tunable laser ripple in the embodiment of the present invention
Long regulation, to make the intensity of reflected light be adjusted to the direction of target intensity value, it is favorably improved the inspection of acoustic emission detection system
Survey sensitivity and accuracy.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the required accompanying drawing used in technology description to be briefly described, it should be apparent that, drawings in the following description are only this
Inventive embodiments, for those of ordinary skill in the art, on the premise of not paying creative work, can also be according to carrying
The accompanying drawing of confession obtains other accompanying drawings.
Fig. 1 is the structural representation of the existing acoustic emission detection system based on fiber-optic grating sensor；
Fig. 2 is that a kind of structure of the acoustic emission detection system provided in an embodiment of the present invention based on fiber-optic grating sensor is shown
It is intended to；
Fig. 3 is another structure of the acoustic emission detection system provided in an embodiment of the present invention based on fiber-optic grating sensor
Schematic diagram；
Fig. 4 is the structural representation of phase-shifted grating in acoustic emission detection system provided in an embodiment of the present invention；
Fig. 5 is the reflectance spectrum figure of phase-shifted grating in acoustic emission detection system provided in an embodiment of the present invention；
Fig. 6 is the flow chart of the acoustic emission detection method provided in an embodiment of the present invention based on fiber-optic grating sensor.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation describes, it is clear that the described embodiment of the present invention is only part of the embodiment of the present invention, rather than whole implementation
Example.Based on the embodiment in the present invention, what those of ordinary skill in the art were obtained under the premise of creative work is not made
Every other embodiment, belongs to the scope of protection of the invention.
The embodiments of the invention provide a kind of acoustic emission detection system based on fiber-optic grating sensor, as shown in Fig. 2 bag
Include tunable laser 21, fiber-optic grating sensor 22, photoelectric detection module 23, servo-drive system 24, wave filter 27 and conciliate mode transfer
Block 25.
Wherein, tunable laser 21 refers to the laser that can continuously change laser output wavelength within the specific limits.
In embodiments of the present invention, tunable laser 21 is used to provide light source for fiber-optic grating sensor 22, so that fiber grating passes
The incident light of sensor 22 is the light of specific wavelength.
Fiber-optic grating sensor 22 is arranged on the inside or surface of monitored object 20, is produced for detecting monitored object 20
Raw acoustic emission signal.Wherein, in the presence of acoustic emission signal caused by monitored object 20, fiber-optic grating sensor 22 is anti-
The centre wavelength for the light penetrated can shift.
Photoelectric detection module 23 is used for the reflected light of detection fiber grating sensor 22, and the reflected light signal is converted to
Electric signal.Wherein, photoelectric detection module 23 includes but are not limited to photodetector.
Servo-drive system 24 is used to judge that fiber-optic grating sensor 22 reflects according to the electric signal that photoelectric detection module 23 exports
Whether the intensity of light is target intensity value, if it is not, then adjusting the wavelength of the emergent light of tunable laser 21, makes optical fiber grating sensing
The intensity of the reflected light of device 22 is adjusted to the direction of the target intensity value, and the electric signal that photoelectric detection module 23 exports is transferred to
Demodulation module 25.
Demodulation module 25 is used to determine that fiber-optic grating sensor 22 reflects according to the electric signal that photoelectric detection module 23 exports
The center wavelength shift amount of light or the intensity of reflected light, and closed according to the center wavelength shift amount is corresponding with acoustic emission signal
The corresponding relation of the intensity and acoustic emission signal of system or reflected light determines acoustic emission signal caused by monitored object 20.
Wherein, the servo-drive system 24 includes at least one amplifier, and the amplifier is used for can by negative-feedback signal control
Tuned laser 21 is inputted to adjust the wavelength of the emergent light of tunable laser 21.Servo-drive system 24 passes through a negative-feedback control
The wavelength of the emergent light of tunable laser 21 processed；Servo-drive system 24 can also can by secondary negative-feedback or multiple negative feedback control
The wavelength of the emergent light of tuned laser 21；
The wave filter 27 is located on the path of the negative-feedback signal, and the wave filter 27 is used to filter out higher than pre-
If the signal of frequency, to adjust the wavelength of the tunable laser emergent light.
The wave filter 27 can be it is one or more, comprising but should not only be understood as individually being installed on signal path
The device or unit of the specific circuit NOR circuit for specially realizing filter function.The wave filter 27 can also have other work(
Energy.The wave filter 27 can be an entirety, can also be by the electricity for the path different piece for being distributed in the negative-feedback signal
The device or unit of road NOR circuit are formed, and these different devices or the respective filtering characteristic of unit can be different, by them
Filtering characteristic be subject to overall when considering, reach the effect for filtering the signal higher than predeterminated frequency.Wherein filter higher than default frequency
The signal of rate, do not imply that the signal that corresponding frequencies are completely eliminated, and refer to that art technology can reach to corresponding band
Signal intensity reach the decay of specific degrees, so as to which relative to the situation of no decay, interference can be reduced.
In the present embodiment, the course of work of above-mentioned acoustic emission detection system is：Fiber-optic grating sensor 22 can continue to reflect
The emergent light of tunable laser 21, once monitored object 20 produces acoustic emission signal, then fiber-optic grating sensor 22 reflects
The centre wavelength of light can shift, and the intensity of reflected light changes, and fiber coupler 26 is by another optical fiber by optical fiber
The reflected light pass of grating sensor 22 is to photoelectric detection module 23, after photoelectric detection module 23 detects center wavelength shift
Electric signal can be converted into after reflected light signal and is transmitted to servo-drive system 24 and demodulation module 25；The basis of servo-drive system 24
The intensity of the electric signal obtains the intensity of the reflected light of fiber-optic grating sensor 22, and judges whether the intensity of reflected light is that target is strong
Angle value, if it is not, then controlling amplifier to pass through the input of negative-feedback signal control tunable laser 21 to adjust tunable laser
The wavelength of the emergent light of device 21, so that the intensity of the reflected light of fiber-optic grating sensor 22 adjusts to the direction of target intensity value；It is adjustable
The input of humorous laser 21 can be voltage or electric current；The electric signal that demodulation module 25 exports according to the photoelectric detection module 23
Determine its variable quantity, the offset of the optical grating reflection center wavelength of light in the variable quantity reflection fiber-optic grating sensor 22 of electric signal
Or the change of the intensity of reflected light, then according to the corresponding relation or reflected light of the center wavelength shift amount and acoustic emission signal
Strength Changes and the corresponding relation of acoustic emission signal determine what the Strength Changes of center wavelength shift amount or reflected light were reflected
Acoustic emission signal caused by monitored object.
It was found from above-mentioned technical proposal, the acoustic emission detection system provided in an embodiment of the present invention based on fiber-optic grating sensor
System, servo-drive system can judge whether the intensity of reflected light is target intensity value according to the electric signal that photoelectric detection module exports, if
It is no, then the wavelength of tunable laser emergent light is adjusted, so that the intensity of reflected light adjusts to the direction of target intensity value, it is described
The electric signal of photoelectric detection module output is transferred to demodulation module, and demodulation module determines the middle cardiac wave of reflected light according to electric signal
The intensity of long offset or reflected light, and according to the strong of the corresponding relation or reflected light of center wavelength shift amount and acoustic emission signal
Degree and the corresponding relation of acoustic emission signal determine acoustic emission signal caused by monitored object, pass through servo in the embodiment of the present invention
Regulation of the system to tunable laser wavelength, to make the intensity of reflected light adjust to the direction of target intensity value, help to carry
The sensitivity of the detection transmitting light of high acoustic emission detection system and accuracy.
In above-mentioned acoustic emission detection system, optical fiber is connected between tunable laser 21 and fiber-optic grating sensor 22
Coupler 26, as shown in Fig. 2 wherein, tunable laser 21, fiber-optic grating sensor 22, fiber coupler 26 and photoelectricity are visited
Surveying the annexation of module 23 is：
The light extraction end of tunable laser 21 and one end of optical fiber connect, and the emergent light of such tunable laser 21 is with regard to energy
Reach the fiber-optic grating sensor 22 of the optical fiber other end by optical fiber, the grating in fiber-optic grating sensor 22 can reflect spy
The reflected light of standing wave length, wherein, fiber coupler 26 can assign to the reflected light of the grating of fiber-optic grating sensor 22 another
On bar optical fiber.There is photoelectric detection module 23 on another optical fiber, i.e., one end of another optical fiber is connected with fiber coupler 26,
The other end is connected with photoelectric detection module 23.Further, one end of servo-drive system 24 is connected with photoelectric detection module 23, is another
End is connected with the input of tunable laser 21, and demodulation module 25 is connected with the output end of photoelectric detection module 23.
It should be noted that amplifier can be operational amplifier in servo-drive system 24, or instrument amplifier, when
It can be so not limited to that with other amplifiers, the embodiment of the present invention.In addition, the servo-drive system 24 in the present embodiment is to adjustable
After the wavelength of humorous laser 21 is adjusted, the intensity of the reflected light of fiber-optic grating sensor 22 can be close to target intensity value, so
Photoelectric detection module 23 just more can delicately detect optical signal, sensitive so as to improve the detection of acoustic emission detection system
Degree.
Explanation is needed further exist for, the sensitivity of fiber-optic grating sensor 22 and grating reflection spectral slope linear zone are oblique
Rate is closely related, and reflectance spectrum slope linear zone slope is bigger, and Output optical power dither amplitude is bigger, fiber-optic grating sensor 22
Sensitivity it is higher.The grating in fiber-optic grating sensor 22 in the present embodiment can be phase-shifted grating, phase-shifted grating bag
Include the structure of multiple discontinuous refractive index periodics changes, the reflectance spectrum of phase-shifted grating is as shown in figure 5, horizontal seat in Fig. 5
Mark W represents wavelength, and ordinate R represents reflectivity, and the middle of the reflectance spectrum of phase-shifted grating introduces an extremely narrow depression,
The a width of micromicron magnitude of band of the depression.In a particular application, can be by the reflected light λ of fiber-optic grating sensor 220Centre wavelength
It is locked on the slope A of phase-shifted grating reflectance spectrum intermediate recess, to realize the high sensitivity of fiber-optic grating sensor 22.It is all kinds of
The fiber-optic grating sensor of type has different reflective spectral properties, but the reflectance spectrum slope similar with slope A in Fig. 5 all be present
The larger ideal operation section of linear zone slope, by reflected light λ0Centre wavelength when being locked in ideal operation section, help
In the higher sensitivity of acquisition.
Servo-drive system 24 in the present embodiment can be according to the intensity and the ripple of the emergent light of tunable laser 21 of reflected light
Long corresponding relation is adjusted at least with the next item down：The target intensity value, the wavelength of the emergent light of the tunable laser 21, institute
State the positive-negative polarity of negative-feedback signal.Wherein, servo-drive system 24 can by adjusting the wavelength of the emergent light of tunable laser 21,
Obtain the intensity of the reflected light under the wavelength of the different emergent lights of tunable laser 21.
In varied situations, for example, under different temperatures, for the incident light of phase co-wavelength, fiber-optic grating sensor 22 is anti-
Penetrating optical wavelength can be different, it is possible to can deviate from ideal operation section.Gone out according to the intensity of reflected light and tunable laser 21
Penetrate the corresponding relation of the wavelength of light, adjust target intensity value, the wavelength of the emergent light of tunable laser 21, negative-feedback signal are just
It is one or more in negative polarity, it will help by the reflected light λ of fiber-optic grating sensor 220Centre wavelength be locked in it is specific
Ideal operation section.Wherein, when changing the positive-negative polarity of negative-feedback signal, can form new negative-feedback makes fiber grating
The reflected light λ of sensor 220Centre wavelength be locked in the reflectance spectrum slope linear zone of opposite slope.
Wherein, the intensity of reflected light and the corresponding relation of the wavelength of the emergent light of tunable laser 21 can be passed through by history
Value acquisition is tested, can also be obtained by other means.For example, the emergent light of tunable laser 21 is controlled by servo-drive system 24
Wavelength change within the specific limits, and by photoelectric detection module 23 monitor the reflected light of fiber-optic grating sensor 22 intensity,
The intensity i.e. ripple of tunable laser 21 of the reflected light under the wavelength of the different emergent lights of tunable laser 21 can be obtained
The corresponding relation of the long intensity with the reflected light of fiber-optic grating sensor 22.
On the basis of some embodiments, as shown in figure 3, acoustic emission detection system in the present embodiment can also include with
The connected control system 28 of the output end of demodulation module 25, the control system 28 are used for the sound emission for mediating the solution of demodulation module 25
Signal is contrasted with reference data, to obtain the health degree value of monitored object 20, wherein, reference data includes monitored
The test data of the caused acoustic emission signal under different health degrees of object 20.In addition, the control system 28 can be also used for
Judge whether the health degree value exceeds early warning value, if so, then starting warning system, prompt human observer to enter monitored object 20
Row is safeguarded, avoids the generation of major accident.
In addition, the acoustic emission detection system in the present embodiment can also include correction module, the correction module is used for basis
Environmental noise is to skew of the influence value of the center wavelength shift amount of the reflected light of fiber-optic grating sensor 22 to the centre wavelength
Amount be corrected or according to environmental noise to the influence value of the strength offsets amount of the reflected light of fiber-optic grating sensor 22 to described anti-
The offset for penetrating the intensity of light is corrected, and improves the precision of the acoustic emission signal demodulated, so as to preferably assess quilt
The health degree value of monitoring object 20.
On the basis of some embodiments, the predeterminated frequency is a × f, wherein, f is the sound emission of desired detection
Low-limit frequency, a are less than 1,1/2,1/4,1/10,1/100 or 1/1000, and certainly, the embodiment of the present invention is not limited to that, can be with
A value is set according to actual conditions.
On the basis of some embodiments, the acoustic emission detection system in the present embodiment includes at least one TEMP
Device, the ambient temperature data for detection fiber grating sensor 22；Servo-drive system 24 can detect according to temperature sensor
Ambient temperature data and the corresponding relation of temperature and the wavelength of tunable laser 21 adjust at least with the next item down：The target
Intensity level, the wavelength of the emergent ray of the tunable laser 21, the positive-negative polarity of the negative-feedback signal.
At different temperatures, using the emergent light of tunable laser 21 of different wave length, help to make optical fiber grating sensing
Device 22 reflects center wavelength of light and is locked in specific ideal operation section.According to temperature and the ripple of the emergent light of tunable laser 21
Long corresponding relation, target intensity value is adjusted, in the wavelength of the emergent light of tunable laser 21, the positive-negative polarity of negative-feedback signal
It is one or more, it will help by the reflected light λ of fiber-optic grating sensor 220Centre wavelength be locked in specific preferable work
Make section.
Wherein, temperature and the corresponding relation of the wavelength of the emergent light of tunable laser 21 can be obtained by historical experience value
, it can also obtain by other means.For example, at a certain temperature, tunable laser 21 is controlled by servo-drive system 24
The wavelength of emergent light change within the specific limits, and pass through photoelectric detection module 23 and monitor the reflected light of fiber-optic grating sensor 22
Intensity, and measure the corresponding relation for the wavelength for drawing this specified temp and the emergent light of tunable laser 21.
In the embodiment of the present invention, fiber-optic grating sensor 22 is the acoustic emission sensor based on Fiber Bragg Grating FBG, cloth
Glug fiber grating is the structure changed caused by fiber cores along the refractive index periodic of fibre core axial arranging, as shown in figure 4,
The more black fractional index of color is different from the refractive index of the shallower part of color, and this periodically variable structure only reflects specific
The light λ of wavelength0, the light of other wavelength can continue to propagate through grating along optical fiber.
Because acoustic emission signal is mechanical wave, the mechanical wave can cause the shake of optic fiber grating wavelength, i.e., believe in sound emission
In the presence of number, the reflected light λ of fiber-optic grating sensor 220Centre wavelength can shift, pass through photoelectric detection module 23
After detecting optical signal and converting optical signals to electric signal, the sound emission according to corresponding to demodulating electric signal of demodulating system 24 is believed
Number, with regard to acoustic emission signal caused by monitored object 20 can be obtained.
Wherein, the sensitivity of fiber-optic grating sensor 22 and grating reflection spectral slope linear zone slope are closely related, instead
Penetrate that spectrum slope linear zone slope is bigger, and Output optical power dither amplitude is bigger, the sensitivity of fiber-optic grating sensor 22 is got over
It is high.Grating in fiber-optic grating sensor 22 can be phase-shifted grating, and phase-shifted grating includes multiple discontinuous refractive index cycles
Property change structure, as shown in figure 5, the abscissa W in Fig. 5 represents wavelength, ordinate R represents anti-for the reflectance spectrum of phase-shifted grating
Rate is penetrated, the middle of the reflectance spectrum of phase-shifted grating introduces an extremely narrow depression, a width of micromicron magnitude of band of the depression.
, can be by the reflected light λ of fiber-optic grating sensor 22 in concrete application0Centre wavelength be locked among phase-shifted grating reflectance spectrum
On the slope A of depression, to realize the high sensitivity of fiber-optic grating sensor 22.
Certainly, the embodiment of the present invention is not limited to that, the grating in fiber-optic grating sensor 22 in the present embodiment can
Think phase-shifted grating (pi-FBG), chirp grating (CFBG), chirp grating to (CFBG pairs), Fabry Perot interference-type
Fiber bragg grating sensor (Fabry-Perot), overlapping grating or the grating that partly overlaps (Superimposed chirped FBG/
Partially overlapped chirped FBG), cascaded fiber grating (cascaded chirped FBGs with/without
Spacing between), one of sampling optical fiber grating (chirped sampled FBGs) or combination.
The embodiment of the present invention additionally provides a kind of acoustic emission detection method based on fiber-optic grating sensor, applied to as above
The acoustic emission detection system based on fiber-optic grating sensor that any embodiment provides, as shown in fig. 6, including：
S601：The acoustic emission signal of monitored object is detected by fiber-optic grating sensor, wherein believing in the sound emission
In the presence of number, the centre wavelength of the reflected light of the fiber-optic grating sensor can shift.
S602：The reflected light of the fiber-optic grating sensor is detected by photoelectric detection module, and the reflected light is turned
It is changed to electric signal.
S603：Judge whether the intensity of the reflected light is target intensity value according to the electric signal by servo-drive system,
If it is not, then enter S604.
S604：The wavelength of the tunable laser emergent light is adjusted, so that the intensity of the reflected light is to the target
The direction adjustment of intensity level.
S605：The center wavelength shift amount or described anti-of the reflected light is determined according to the electric signal by demodulation module
Penetrate the intensity of light, and according to the intensity of the corresponding relation or the reflected light of the center wavelength shift amount and acoustic emission signal with
The corresponding relation of acoustic emission signal determines acoustic emission signal caused by the monitored object.
During acoustic emission detection system works, fiber-optic grating sensor can continue reflection tunable laser outgoing
The light of specific wavelength in light, once monitored object produces acoustic emission signal, then the center of the light of fiber-optic grating sensor reflection
Wavelength can shift, fiber coupler by optical fiber by the reflected light pass of fiber-optic grating sensor to photoelectric detection module,
Photoelectric detection module can be converted into electric signal after detecting the reflected light signal after center wavelength shift and transmit to servo
System and demodulation module；
Servo-drive system obtains the intensity of fiber-optic grating sensor reflected light according to the intensity of the electric signal, and judges reflected light
Intensity whether be target intensity value, if it is not, then control amplifier pass through negative-feedback signal control tunable laser input
(input voltage or input current) adjusts the wavelength of tunable laser emergent light, so that fiber-optic grating sensor reflected light
Intensity adjusts to the direction of target intensity value；
The electric signal that photoelectric detection module exports is obtained the change of electric signal by demodulation module compared with standard electric signal
Change amount, the offset or described of the optical grating reflection center wavelength of light in fiber-optic grating sensor is determined according to the variable quantity of electric signal
The intensity of reflected light, then according to the intensity of the corresponding relation or the reflected light of center wavelength shift amount and acoustic emission signal with
The corresponding relation of acoustic emission signal determines acoustic emission signal caused by monitored object.
It was found from above-mentioned technical proposal, the acoustic emission detection side provided in an embodiment of the present invention based on fiber-optic grating sensor
Method, it can judge whether the intensity of reflected light is target strength according to the electric signal that photoelectric detection module exports by servo-drive system
Value, if it is not, the wavelength of tunable laser emergent light is then adjusted, so that the intensity of reflected light is adjusted to the direction of target intensity value
Whole, the electric signal of the photoelectric detection module output is transferred to demodulation module, is determined instead according to electric signal by demodulation module
The center wavelength shift amount of light or the intensity of the reflected light are penetrated, and it is corresponding with acoustic emission signal according to center wavelength shift amount
The corresponding relation of the intensity and acoustic emission signal of relation or the reflected light determines acoustic emission signal caused by monitored object, this
By regulation of the servo-drive system to tunable laser wavelength in inventive embodiments, the detection spirit of acoustic emission detection system is improved
Sensitivity and accuracy.
In addition, the acoustic emission detection method in the present embodiment also includes：By control system by the acoustic emission signal with
Reference data is contrasted, and to obtain the health degree value of the monitored object, the reference data includes described monitored
The test data of object caused acoustic emission signal under different health degrees.
Further, the acoustic emission detection method in the present embodiment also includes：The health degree is judged by control system
Whether value exceeds early warning value, if so, then starting warning system with alert, prompts human observer to carry out monitored object
Safeguard, avoid the generation of major accident.
In addition, the acoustic emission detection method in the present embodiment can also include：By correction module according to environmental noise pair
The influence value of the center wavelength shift amount of fiber-optic grating sensor reflected light the offset of the centre wavelength is corrected or
According to environmental noise to the influence value of the strength offsets amount of fiber-optic grating sensor reflected light to the inclined of the intensity of the reflected light
Shifting amount is corrected；To improve the precision of the acoustic emission signal demodulated, so as to preferably assess the strong of monitored object
Health degree value.
Further, when acoustic emission detection system also includes at least one temperature sensor, the sound hair in the present embodiment
Penetrating detection method can also include：The ambient temperature data of temperature sensor detection fiber grating sensor；Servo-drive system according to
The corresponding relation regulation of ambient temperature data and temperature that temperature sensor detects and tunable laser wavelength at least with
The next item down：The target intensity value, the wavelength of the tunable laser emergent ray, the both positive and negative polarity of the negative-feedback signal
Property.
In this specification between each embodiment identical similar portion mutually referring to.For disclosed in embodiment some
Device and certain methods are corresponding, can mutual reference.
The foregoing description of the disclosed embodiments, professional and technical personnel in the field are enable to realize or using the present invention.
A variety of modifications to these embodiments will be apparent for those skilled in the art, as defined herein
General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, it is of the invention
The embodiments shown herein is not intended to be limited to, and is to fit to and principles disclosed herein and features of novelty phase one
The most wide scope caused.
Claims (10)
1. a kind of acoustic emission detection system based on fiber-optic grating sensor, it is characterised in that including tunable laser, optical fiber
Grating sensor, photoelectric detection module, demodulation module, wave filter and servo-drive system；
The tunable laser is used to provide light source for the fiber-optic grating sensor, so that the fiber-optic grating sensor
Incident light is the light of specific wavelength in the light source；
The fiber-optic grating sensor is used for the acoustic emission signal for detecting monitored object, wherein, caused by monitored object
In the presence of acoustic emission signal, the centre wavelength of the reflected light of the fiber-optic grating sensor can shift；
The photoelectric detection module is used for the reflected light for detecting the fiber-optic grating sensor, and the reflected light is converted into electricity
Signal；
The servo-drive system is used to judge whether the intensity of the reflected light is target intensity value according to the electric signal, if it is not,
The wavelength of the tunable laser emergent light is then adjusted, so that the intensity of the reflected light is to the direction of the target intensity value
Adjustment；
The electric signal of the photoelectric detection module output is transferred to the demodulation module；
The demodulation module is used to determine the center wavelength shift amount of the reflected light or the reflected light according to the electric signal
Intensity, and sent out according to the intensity and sound of the corresponding relation or the reflected light of the center wavelength shift amount and acoustic emission signal
The corresponding relation for penetrating signal determines acoustic emission signal caused by the monitored object；
Wherein, the servo-drive system includes at least one amplifier, and the amplifier is used for by described in negative-feedback signal control
Tunable laser is inputted to adjust the wavelength of the tunable laser emergent light；
The wave filter is located on the path of the negative-feedback signal, and the wave filter is used to filter out the electric signal intermediate frequency
Rate is higher than the signal of predeterminated frequency, to adjust the wavelength of the tunable laser emergent light.
2. detecting system according to claim 1, it is characterised in that the predeterminated frequency is a × f, wherein, a be less than 1,
1/2nd, 1/4,1/10,1/100 or 1/1000.
3. detecting system according to claim 1, it is characterised in that the detecting system also includes control system, described
Control system is used to be contrasted the acoustic emission signal with reference data, to obtain the health degree of the monitored object
Value, the reference data include the test data of monitored object caused acoustic emission signal under different health degrees.
4. detecting system according to claim 1, it is characterised in that the servo-drive system, for according to the reflected light
The corresponding relation of wavelength of intensity and the tunable laser emergent light adjust at least with the next item down：The target strength
Value, the wavelength of the tunable laser emergent light, the positive-negative polarity of the negative-feedback signal.
5. detecting system according to claim 4, it is characterised in that the servo-drive system, for by can described in regulation
The wavelength of tuned laser emergent light, obtain the strong of the reflected light under the wavelength of the different tunable laser emergent light
Degree.
6. detecting system according to claim 1, it is characterised in that the detecting system also includes at least one temperature and passed
Sensor；
The temperature sensor is used for the ambient temperature data for detecting the fiber-optic grating sensor；
The servo-drive system, for corresponding with the tunable laser wavelength according to the ambient temperature data and temperature
Relation is adjusted at least with the next item down：The target intensity value, the wavelength of the tunable laser emergent ray, the negative-feedback
The positive-negative polarity of signal.
7. detecting system according to claim 1, it is characterised in that the grating in the fiber-optic grating sensor is phase shift
Grating, chirp grating, chirp grating to, Fabry Perot interference-type fiber bragg grating sensor, overlapping grating or the light that partly overlaps
One of grid, cascaded fiber grating, sampling optical fiber grating or combination.
A kind of 8. acoustic emission detection method based on fiber-optic grating sensor, it is characterised in that including：
The acoustic emission signal of the monitored object of detection；
The reflected light of detection fiber grating sensor, and the reflected light is converted into electric signal, wherein believing in the sound emission
In the presence of number, the centre wavelength of the reflected light can shift；
Whether the intensity that the reflected light is judged according to the electric signal is target intensity value；
If it is not, the intensity of the reflected light is then adjusted, so that the intensity of the reflected light is adjusted to the direction of the target intensity value
It is whole；
On the path of negative-feedback signal, the signal that frequency in the electric signal is higher than predeterminated frequency is filtered out, with described in regulation
The wavelength of tunable laser emergent light；The center wavelength shift amount or described anti-of the reflected light is determined according to the electric signal
Penetrate the intensity of light, and according to the intensity of the corresponding relation or the reflected light of the center wavelength shift amount and acoustic emission signal with
The corresponding relation of acoustic emission signal determines acoustic emission signal caused by the monitored object.
9. according to the method for claim 8, it is characterised in that also include：
It is at least following according to the regulation of the corresponding relation of the intensity of the reflected light and the wavelength of the tunable laser emergent light
One：The target intensity value, the wavelength of the tunable laser emergent light, the positive-negative polarity of the negative-feedback signal；
The acoustic emission signal is contrasted with reference data, it is described to obtain the health degree value of the monitored object
Reference data includes the test data of monitored object caused acoustic emission signal under different health degrees.
10. according to the method for claim 9, it is characterised in that also include：
Judge whether the health degree value exceeds early warning value, if so, then alert.
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