CN209841785U - Optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation - Google Patents
Optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation Download PDFInfo
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- CN209841785U CN209841785U CN201920329447.1U CN201920329447U CN209841785U CN 209841785 U CN209841785 U CN 209841785U CN 201920329447 U CN201920329447 U CN 201920329447U CN 209841785 U CN209841785 U CN 209841785U
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Abstract
The utility model discloses an optic fibre acoustic emission system suitable for narrow and small space, temperature self-adaptation utilizes tunable narrowband laser and photoelectric detector as photoelectric conversion device, utilizes the wavelength measuring module to trail the center wavelength of optic fibre bragg grating in real time, combines acoustic emission collection card and preamplifier to establish the optic fibre acoustic emission system of a monitoring solid construction alternating temperature damage destruction process. The system has microsecond-level response speed, and can accurately monitor the damage and failure process of the solid structure in a narrow space.
Description
Technical Field
The utility model relates to a material capability test technical field, concretely relates to optic fibre acoustic emission system suitable for narrow and small space, temperature self-adaptation.
Background
The acoustic emission system can be used for acquiring damage, damage or failure information of a solid structure under a temperature-changing condition, and the conventional acoustic emission system adopts a piezoelectric material as a sensor, so that a probe is large in size and cannot be installed in a slit space. The optical fiber sensor can be installed in a slit space due to fine and flexible volume, and an optical fiber acoustic emission system is established in related documents, but most of the systems cannot be applied to a temperature change test due to the temperature limitation of a sensing principle.
SUMMERY OF THE UTILITY MODEL
In order to overcome the technical defect, the utility model provides an optic fibre acoustic emission system suitable for narrow and small space, temperature self-adaptation, this system have microsecond level response speed, can accurate monitoring solid structure damage in the narrow and small space destroy failure process.
In order to achieve the technical effect, the utility model provides a following technical scheme:
an optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation comprises an optical fiber acoustic emission sensor, a wavelength measuring module, a photoelectric conversion device, a signal acquisition processor and a computer; the optical fiber emission sensor is an optical fiber Bragg grating, the photoelectric conversion device is composed of a tunable narrow-band light source and a photoelectric detector, the optical fiber Bragg grating is respectively connected with the tunable narrow-band laser, the wavelength measuring module and the photoelectric detector through optical fibers, the photoelectric detector is connected with the signal acquisition processor through a signal line, and the wavelength measuring module and the tunable narrow-band light source are respectively connected with the computer.
The technical scheme is that an optical fiber circulator is arranged between the optical fiber acoustic emission sensor and the tunable narrow-band light source and between the optical fiber acoustic emission sensor and the photoelectric detector.
The signal acquisition processor is composed of a preamplifier and an acoustic emission acquisition card, the photoelectric detector is connected with the preamplifier through a signal line, the preamplifier is connected with the acoustic emission acquisition card through a signal line, and the acoustic emission acquisition card is connected with a computer.
The further technical scheme is that the optical fiber acoustic emission sensor is an optical fiber Bragg grating which is free of a coating layer and has a length within a range of 9-11 mm.
The further technical proposal is that the reflectivity of the fiber Bragg grating is more than 80% when the linear area of the fiber Bragg grating is more than 80 pm.
The further technical scheme is that a wide-spectrum light source is arranged in the wavelength measuring module, the wavelength range is 1520-1570 nm, and the power is less than 1 mW.
The further technical scheme is that the wavelength of the tunable narrow-band light source can be continuously tuned, the tuning range is 1520 nm-1570 nm, the precision is less than or equal to 50pm, the width is less than or equal to 10pm, and the power is greater than or equal to 5 mW.
Following the description of the present invention, the wavelength measuring module in the device is used to measure the central wavelength λ of the optical fiber acoustic emission sensor in real timeBA wide-spectrum light source is arranged in the acoustic emission sensor, the wavelength range is 1520-1570 nm, the power is less than 1mW, the fiber Bragg grating is used as the optical fiber acoustic emission sensor, the reflection spectrum of the acoustic emission sensor is an arc-shaped peak, and the lambda isBThe center wavelength is, half of the peak value corresponds to a spectral width of 2 lambdabThe computer obtains lambda at time t1 through the wavelength measurement moduleB(t1) In the system, the light source is incident to the optical fiber acoustic emission sensor through the circulator, and the wavelength value lambda isL(t2) Lambda obtained by computerB(t1) Assigning to λL(t2)＝λB(t1)+λbOr λL(t2)＝λB(t1)-λb，t2-t1>The closer to 50 μ s the better, indicating the source wavelength and fiber acoustic emissionThe wavelength response of the sensors is consistent, acoustic emission signals above 20kHz (1/50 mu s) can be distinguished, the circulator in the application is provided with three ports which are respectively a port I, a port II and a port III, the three ports realize the function of unidirectional light transmission, namely the port I → the port II → the port III, the light loss from the port I to the port II is better, and the light intensity from the port I to the port III is 0; the light intensity from the port to the port I is smaller and better, and the light loss from the port to the port III is smaller and better; the light intensity from port to port is as small as possible, and the light intensity from port to port is 0. The higher the photoelectric detector sensitivity in this application is, the better, convert acoustic emission light intensity signal into analog voltage signal. In the system, a photoelectric detector receives total light intensity I reflected by an optical fiber acoustic emission sensor through a circulator, and the total light intensity I comprises light intensity I of a broadband light source arranged in a wavelength measurement moduleWAnd tunable narrow-band light source intensity INTwo components, the latter being much larger than the former, the total intensity I can be considered to be close to INWherein the broadband light source has light intensity IWAnd the acoustic emission acquisition card is used for acquiring the acoustic emission signals amplified by the preamplifier and inputting the acoustic emission signals into a computer.
Compared with the prior art, the utility model, following beneficial effect has:
in the process of temperature impact explosive, the central wavelength of the fiber Bragg grating adhered to the surface of the solid structure can be changed, the wavelength measuring module can automatically track and measure the central wavelength of the fiber Bragg grating in real time, the measured central wavelength value is assigned to the tunable narrow-band light source through the computer, the wavelength value obtained by the tunable narrow-band light source can be matched with the fiber Bragg grating caused by temperature change, and therefore the temperature self-adaptive acoustic emission monitoring function is achieved.
The utility model discloses regard fiber bragg grating as acoustic emission sensor, utilize tunable narrowband laser and photoelectric detector as photoelectric conversion device, utilize wavelength measuring module real-time tracking fiber bragg grating's center wavelength, combine acoustic emission collection card and preamplifier to establish the fiber acoustic emission system of a monitoring solid structure alternating temperature damage destruction process. The system has microsecond-level response speed, and can accurately monitor the damage and failure process of the solid structure in a narrow space.
Drawings
FIG. 1 is a schematic view of the overall structure of the optical fiber acoustic emission system of the present invention;
FIG. 2 is a schematic view of the reflection spectrum of the optical fiber acoustic emission sensor of the present invention;
fig. 3 is a schematic diagram of the spectrum arriving at the photodetector in the present system.
Detailed Description
Example 1
An optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation as shown in fig. 1 comprises an optical fiber acoustic emission sensor, a wavelength measuring module, a photoelectric conversion device, a signal acquisition processor and a computer; the optical fiber acoustic emission sensor is an optical fiber Bragg grating, the photoelectric conversion device is composed of a tunable narrow-band light source and a photoelectric detector, the optical fiber Bragg grating is respectively connected with the tunable narrow-band laser, the wavelength measuring module and the photoelectric detector through optical fibers, the photoelectric detector is connected with the signal acquisition processor through a signal line, the wavelength measuring module and the tunable narrow-band light source are respectively connected with a computer, and an optical fiber circulator is arranged between the optical fiber acoustic emission sensor and the tunable narrow-band light source as well as between the optical fiber acoustic emission sensor and the photoelectric detector. The circulator is provided with three ports, namely a port I, a port II and a port III, the three ports realize the one-way transmission function of light, namely the port I → the port II → the port III, the light loss from the port I to the port II is smaller and better, and the light intensity from the port I to the port III is 0; the light intensity from the port to the port I is smaller and better, and the light loss from the port to the port III is smaller and better; the light intensity from port to port is as small as possible, and the light intensity from port to port is 0. In the system, a photoelectric detector receives total light intensity I reflected by an optical fiber acoustic emission sensor through a circulator, and the total light intensity I comprises light intensity I of a broadband light source arranged in a wavelength measurement moduleWAnd tunable narrow-band light source intensity INTwo components, the latter being much larger than the former, the total intensity I can be considered to be close toIn INWherein the broadband light source has light intensity IWSmall and not shown. The signal acquisition processor consists of a preamplifier and an acoustic emission acquisition card, the photoelectric detector is firstly connected with the preamplifier through a signal line, then the preamplifier is connected with the acoustic emission acquisition card through a signal line, and the acoustic emission acquisition card is connected with a computer. The optical fiber acoustic emission sensor is an optical fiber Bragg grating which is not provided with a coating layer and has the length within the range of 9-11 mm, the reflectivity of the optical fiber Bragg grating is more than 80pm and is more than or equal to 80%, the wavelength measuring module is internally provided with a wide-spectrum light source, the wavelength range is 1520-1570 nm, the power is less than 1mW, the wavelength of the tunable narrow-band light source can be continuously tuned, the tuning range is 1520 nm-1570 nm, the precision is less than or equal to 50pm, the width is less than or equal to 10pm, and the power is more than or equal to. In the system, the light source is incident to the optical fiber acoustic emission sensor through the circulator, and the wavelength value lambda isL(t2) Lambda obtained by computerB(t1) Assigning to λL(t2)＝λB(t1)+λbOr λL(t2)＝λB(t1)-λb，t2-t1>The closer to 50 mu s, the better, the more the light source wavelength is, the more the response is, the light source wavelength is consistent with the wavelength response of the optical fiber acoustic emission sensor, and the acoustic emission signals above 20kHz (1/50 mu s) can be distinguished, in this application, the preamplifier is used for receiving the analog voltage signals and amplifying the analog voltage signals, and the acoustic emission acquisition card is used for acquiring the acoustic emission signals amplified by the preamplifier and inputting the acoustic emission signals into a computer.
Claims (7)
1. An optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation is characterized by comprising an optical fiber acoustic emission sensor, a wavelength measuring module, a photoelectric conversion device, a signal acquisition processor and a computer; the optical fiber acoustic emission sensor is an optical fiber Bragg grating, the photoelectric conversion device is composed of a tunable narrow-band light source and a photoelectric detector, the optical fiber Bragg grating is respectively connected with the tunable narrow-band laser, the wavelength measuring module and the photoelectric detector through optical fibers, the photoelectric detector is connected with the signal acquisition processor through a signal line, and the wavelength measuring module and the tunable narrow-band light source are respectively connected with the computer.
2. The narrow-space, temperature-adaptive fiber acoustic emission system according to claim 1, wherein a fiber optic circulator is disposed between the fiber acoustic emission sensor and the tunable narrowband light source and the photodetector.
3. The fiber acoustic emission system suitable for narrow space and temperature adaptation according to claim 1, wherein the signal acquisition processor is composed of a preamplifier and an acoustic emission acquisition card, the photoelectric detector is firstly connected with the preamplifier through a signal wire, then the preamplifier is connected with the acoustic emission acquisition card through a signal wire, and the acoustic emission acquisition card is connected with a computer.
4. The optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation according to claim 1, wherein the optical fiber acoustic emission sensor is a fiber bragg grating with no coating layer and a length in a range of 9-11 mm.
5. The narrow-space and temperature-adaptive fiber acoustic emission system according to claim 4, wherein the reflectivity of the fiber Bragg grating is greater than 80% in the linear region and greater than 80 pm.
6. The narrow-space and temperature-adaptive fiber acoustic emission system according to claim 1, wherein the wavelength measurement module is internally provided with a wide-spectrum light source, the wavelength range is 1520-1570 nm, and the power is less than 1 mW.
7. The fiber acoustic emission system suitable for use in a small space and temperature adaptation according to claim 1, wherein the wavelength of the tunable narrowband optical source can be continuously tuned, the tuning range is 1520nm to 1570nm, the precision is less than or equal to 50pm, the width is less than or equal to 10pm, and the power is greater than or equal to 5 mW.
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| CN201920329447.1U CN209841785U (en) | 2019-03-14 | 2019-03-14 | Optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation |
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| CN201920329447.1U CN209841785U (en) | 2019-03-14 | 2019-03-14 | Optical fiber acoustic emission system suitable for narrow space and temperature self-adaptation |
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