CN102080986B - Fiber bragg grating vibration sensing component, fiber bragg grating vibration sensing device, vibration measuring system and method - Google Patents

Abstract

The invention discloses a fiber bragg grating vibration sensing component, which comprises a base part, an end part, a cantilever beam and a fiber bragg grating strain gauge, wherein the end part constitutes a vibration mass block; the cantilever beam is connected between the base part and the end part; the cantilever beam constitutes a vibration amplification arm; two ends of the fiber bragg grating strain gauge are fixed on the base part and the end part respectively; and the fiber bragg grating strain gauge is used for detecting the strain of the cantilever beam. The invention also relates to a fiber bragg grating vibration sensing device, a vibration measuring system and method.

Description

Fiber Bragg Grating Vibration Sensing Component, Fiber Bragg Grating Vibration Sensing Device, Vibration Measuring System and Method

technical field

The invention relates to a fiber grating vibration sensing component, a fiber grating vibration sensing device, a vibration measuring system and a method.

Background technique

In the prior art, commonly used sensors for measuring vibration include acceleration sensors, speed sensors and displacement sensors. The acceleration sensor uses piezoelectric crystals to convert the acceleration signal into a charge signal, and the speed sensor uses the principle of electromagnetic induction to convert the speed signal into a voltage signal. , The displacement sensor uses the eddy current effect to convert the displacement signal into an electrical signal. However, the aforementioned sensors are all based on the principle of converting mechanical energy into electrical energy. When using the above-mentioned sensors to sense the vibration of rails or sleepers, since there is a high-voltage power source forming an interference source near the rails, the above-mentioned electric sensors have the problem of low measurement accuracy in high magnetic field and high electric field environments.

The fiber grating sensor has the advantages of anti-electromagnetic interference, small size (standard bare fiber is 125um), and light weight.

Contents of the invention

The present invention was proposed based on the above problems.

According to one aspect of the present invention, a fiber grating vibration sensing component includes: a base; an end, the end constituting a vibrating mass; a fiber grating strain gauge, the two ends of the fiber grating strain gauge are respectively fixed on the base and an end portion for detecting the strain of the cantilever beam; and a cantilever beam connected between the base and the end portion, the cantilever beam constituting a vibration amplifying arm.

Advantageously, the vibration amplifying arm may be a constant-strength strain beam. Further, the base, the end and the vibration amplifying arm may be formed in one piece.

形的开口；或者所述一体件的纵向截面具有矩形开口。Advantageously, the upper surface of the base and/or the upper surface of the end is higher than the upper surface of the vibration amplification arm, and the two ends of the fiber grating strain gauge are respectively fixed on the upper surface of the base and the end on the upper surface. Specifically, the longitudinal section of the integral piece has a

shaped opening; or the longitudinal section of the one-piece has a rectangular opening.

The base can be fixed directly or indirectly to the rail.

Advantageously, an additional mass is attached to said end for adjusting the total mass of the end.

According to the fiber grating vibration sensing part of the present invention, the structure is simple, the dynamic response is good, the sensitivity is good, the resolution is strong, and the displacement of 0.01um or even smaller can be measured. The environment can ensure that the signal is not distorted and can be transmitted normally.

According to another aspect of the present invention, a fiber grating vibration sensing device is proposed, which includes: the above-mentioned fiber grating vibration sensing component; and a fiber grating demodulation instrument, the fiber grating demodulation instrument includes a light source and an optical cable, wherein The optical cable guides the light emitted by the light source to the fiber grating of the fiber grating vibration sensing part; and the fiber grating demodulation instrument receives the light reflected back from the fiber grating and is adapted to output a signal reflecting the reflected light Light is an electrical signal that changes in wavelength due to the strain.

According to another aspect of the present invention, a vibration measurement system is proposed, which includes: the above-mentioned fiber grating vibration sensing component; a fiber grating demodulation instrument, the fiber grating demodulation instrument includes a light source and an optical cable, wherein the optical cable will The light emitted by the light source is guided to the fiber grating of the fiber grating vibration sensing part, and the fiber grating demodulation instrument receives the light reflected back from the fiber grating and outputs a signal reflecting the change of the wavelength of the reflected light an electrical signal; and analyzing means for determining a vibration amplitude and/or a vibration frequency of the base or end of the fiber grating vibration sensing component based on the electrical signal.

Advantageously, the vibration measurement system further includes an early warning device, which sends an alarm when the vibration amplitude of the base or end of the fiber grating vibration sensing part exceeds a predetermined amplitude and/or the vibration frequency is outside a predetermined frequency range .

Advantageously, there are multiple fiber grating vibration sensing components, the light source is a broadband light source, and an optical cable guides the light emitted by the broadband light source to the fiber grating of each fiber grating vibration sensing component so that the optical fiber is connected in series a grating, wherein each fiber grating is capable of reflecting light in a corresponding wavelength range of the light, and the corresponding wavelength ranges do not overlap with each other; the fiber grating demodulation instrument receives light reflected back from each fiber grating and outputs a The electrical signal of the change of the wavelength of the light; and the analysis device determines the vibration amplitude and/or vibration frequency of the base or end of each fiber grating vibration sensing part based on the electrical signal.

Alternatively, there are multiple fiber grating vibration sensing components and are divided into multiple groups, the light source is a broadband light source, and there are multiple optical cables, wherein each optical cable guides the light emitted by the broadband light source to a fiber grating of each fiber grating vibration sensing component in a corresponding fiber grating vibration sensing component group so as to connect the fiber gratings in the group in series, wherein each fiber grating is capable of reflecting light of a corresponding wavelength range in the light, and The corresponding wavelength ranges do not overlap with each other; the fiber grating demodulation instrument receives light reflected back from each fiber grating and outputs an electrical signal reflecting a change in wavelength of the reflected light; and the analysis device is based on the electrical signal The vibration amplitude and/or vibration frequency of the base or end of each fiber grating vibration sensing component is determined. Advantageously, the multiple groups of fiber grating vibration sensing components are sequentially arranged at intervals.

The present invention also proposes a vibration measurement system for rails, which includes: a signal capture module, a signal analysis module and an accident alarm module, wherein the signal capture module includes the above-mentioned fiber grating vibration sensing component.

According to yet another aspect of the present invention, a vibration measurement method is proposed, which uses the above-mentioned fiber grating vibration sensing component, and the vibration measurement method includes the following steps: rigidly connecting the base to the object to be measured; providing a fiber grating solution The fiber grating demodulation instrument includes a light source and an optical cable; the light from the light source is provided to the fiber grating by using the optical cable; the fiber grating demodulation instrument receives the light reflected back from the fiber grating and outputs the reflected light due to the and determining the vibration amplitude and/or vibration frequency of the base or end of the fiber grating vibration sensing component based on the electrical signal.

Further, based on the vibration amplitude and/or vibration frequency of the base or end of the fiber grating vibration sensing component, the vibration amplitude and/or vibration frequency at the corresponding position of the object to be tested can be determined.

By using the vibration measuring system and the vibration measuring method of the present invention, vibration signals can be detected accurately.

Description of drawings

1 is a schematic diagram of a vibration structure of a fiber grating vibration sensing component according to an embodiment of the present invention;

Fig. 2 shows the schematic diagram of fixing the fiber grating strain gauge to the vibrating structure shown in Fig. 1;

Fig. 3 shows the schematic diagram of installing the fiber grating vibration sensing part shown in Fig. 2 on the object under test such as rail;

Fig. 4 is the schematic diagram of the modification of the vibration structure of fiber grating vibration sensing part of the present invention; With

Fig. 5 is a schematic diagram of another modification of the vibration structure of the fiber grating vibration sensing component of the present invention.

Detailed ways

The technical solutions of the present invention will be further specifically described below through the embodiments and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals designate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention, but should not be construed as a limitation of the present invention.

Fig. 1, Fig. 2 and Fig. 3 show the fiber grating vibration sensing component 10 of the present invention. Specifically, Fig. 1 is a schematic diagram of the vibration structure of the fiber grating vibration sensing part of the present invention; Fig. 2 shows a schematic diagram of fixing the fiber grating strain gauge to the vibration structure shown in Fig. 1; Fig. 3 shows the Schematic diagram of the fiber grating vibration sensing component installed on the rail.

As shown in Figures 1 and 2, the fiber grating vibration sensing component 10 includes: a base 1; an end 2, which constitutes a vibrating mass; a cantilever beam 3, which is connected between the base 1 and the end 2, the cantilever beam 3 constitutes a vibration amplification arm; the fiber grating strain gauge 4, the two ends 4a, 4b of the fiber grating strain gauge 4 are respectively fixed on the base 1 and the end 2, for detecting the cantilever beam strain.

The fiber grating strain gauge 4 can be fixed on the base part 1 and the end part 2 by electric welding, adhesion and other means.

One end 4a of the fiber grating strain gauge 4 is fixed on the upper surface 1a of the base 1, and the other end 4b is fixed on the upper surface 2a of the end part 2. As shown in FIG. extend in parallel in order to detect the strain of the cantilever beam 3 .

It should be pointed out that although the description herein is based on the fiber Bragg grating strain gauge 4, it can also be applied to the fiber Bragg grating.

Here, the base 1 is rigidly connected to the object under test 5 and adapted to vibrate with the vibration of the object under test 5 . It should be noted that the rigid connection here can mean direct fixing or indirect fixing, as long as the base part 1 and thus the end part 2 are suitable for vibrating with the vibration of the object under test 5 . As shown in FIG. 3 , in this embodiment, the base 1 is directly rigidly fixed to the object under test 5 for detecting the vibration of the object under test 5 . However, it should be noted that the base 1 may also be indirectly fixed to the object under test 5 through other intermediates.

For ease of description, as shown in Figure 1, it may be desirable to define the X direction as the transverse direction (or called the width direction) of the fiber Bragg grating vibration sensing component 10, and the Y direction as the longitudinal direction (or called the width direction) of the fiber Bragg grating vibration sensing component 10. length direction), and the Z direction is the height direction (or thickness direction) of the fiber grating vibration sensing component.

The vibration amplifying arm 3 can be a constant-intensity strain beam. That is, the deformation of the vibration amplification arm 3 along the longitudinal direction is linear. In this case, the optical fiber in the fiber grating strain gauge 4 produces linear deformation along the longitudinal direction. The vibration amplifying arm 3 can be designed in a roughly triangular shape, that is, the width of the vibration amplifying arm 3 gradually decreases from the base 1 to the end 2 . Of course, the vibration amplifying arm 3 may also be designed in a wedge shape, that is, the thickness of the vibration amplifying arm 3 gradually decreases from the base 1 to the end 2 . Of course, any known technology can also be used to design the vibration amplifying arm 3 so that it has the property of a constant-intensity strain beam. However, the vibration amplifying arm 3 may not be an equal-intensity strain beam.

The base 1, the end 2 and the vibration amplifying arm 3 may be formed in one piece. However, it should be noted that the present invention is not limited thereto, and the base part 1 , the end part 2 and the vibration amplifying arm 3 may also be three independent components connected to each other in a detachable manner.

In order to amplify the vibration of the end portion 2, the upper surface 1a of the base portion 1 and/or the upper surface 2a of the end portion 2 are higher than the upper surface 3a of the vibration amplification arm 3, and the two ends 4a, 4b of the fiber grating strain gauge 4 are respectively It is fixed or attached on the upper surface 1a of the base part 1 and the upper surface 2a of the end part 2, as shown in FIG. 2 . In this way, based on the amplification of the vibration of the end part 2, the response of the fiber grating strain gauge 4 will be more sensitive.

形的开口，当然，该一体件的纵向截面也可以具有呈

形的开口。In this implementation, the end part 2 can be opened with an inward notch 2c, so that the longitudinal section of the integral part formed by the base part 1, the end part 2 and the vibration amplifying arm 3 has a shape of

Shaped opening, of course, the longitudinal section of the one piece can also have a

shaped opening.

The one piece can also have different forms. As shown in FIG. 4 , the end 2 is designed as a solid mass without an inwardly facing notch 2c. Thus, the longitudinal section of the integral body formed by the base 1 , the end 2 and the vibration amplifying arm 3 has a rectangular opening.

The end portion 2 has a predetermined mass and thus constitutes a seismic mass. Please note that the thickness of the vibrating amplifying arm 3 is generally thin. As shown in FIG. 5 , an additional mass 6 may also be attached to the end portion 2 for adjusting the total mass of the end portion 2 . The additional mass 6 can be connected to the end 2 by screws.

The working principle of the fiber grating vibration sensing part according to the present invention is illustrated below by taking Fig. 1-3 as an example: when the object to be measured 5 vibrates, the base 1 vibrates, and the end 2 also vibrates thereupon, and the vibration amplifying arm 3 acts as Under the action of the end 2 of the mass block, forced vibration is generated to amplify the vibration, so that the vibration amplification arm 3 can produce a large reciprocating tension and compression action on the fiber Bragg grating strain gauge 4, so that the fiber Bragg grating generates strain, which makes the fiber Bragg grating through The wavelength of the light of the fiber Bragg grating changes, and through the optical cable, the wavelength change is reflected back to the fiber Bragg grating demodulation instrument, and converted into an electrical signal, which can be analyzed based on the electrical signal.

Based on the above-mentioned principle, the present invention proposes a fiber grating vibration sensing device, which includes: any of the fiber grating vibration sensing components mentioned above; and a fiber grating demodulation instrument, which includes a light source and an optical cable, wherein The optical cable guides the light emitted by the light source to the fiber grating of the fiber grating vibration sensing part 10; and the fiber grating demodulation instrument receives the light reflected back from the fiber grating and outputs a wavelength change reflecting the reflected light due to the strain electrical signal.

Based on the above principles, the present invention also proposes a vibration measurement system, including: the above-mentioned fiber grating vibration sensing component; to the fiber grating of the fiber grating vibration sensing part, and the fiber grating demodulation instrument receives the light reflected back from the fiber grating and outputs an electrical signal reflecting the change in the wavelength of the reflected light; and an analysis device based on the electrical signal The signal determines the vibration amplitude and/or vibration frequency of the base 1 or end 2 of the fiber grating vibration sensing component. In actual situations, there is a corresponding relationship between the vibration amplitude of the base 1 or the end 2 and the wavelength change value of the light reflected from the fiber Bragg grating, and the vibration frequency of the base 1 or the end 2 is related to the light reflected from the fiber Bragg grating. There is also a corresponding relationship with the wavelength change rate of .

The vibration measurement system may also include an early warning device, which sends an alarm when the vibration amplitude of the base 1 or end 2 of the fiber grating vibration sensing component exceeds a predetermined amplitude and/or the vibration frequency is outside a predetermined frequency range.

Further, there are multiple fiber grating vibration sensing parts 10, such as 20, and the light source is a broadband light source, and an optical cable guides the light emitted by the broadband light source to the fiber grating of each fiber grating vibration sensing part so that the fiber grating is connected in series , wherein each fiber grating is capable of reflecting light of a corresponding wavelength range in the light, and the corresponding wavelength ranges do not overlap with each other; the fiber grating demodulation instrument receives the light reflected back from each fiber grating and outputs a signal reflecting the reflected light The electrical signal of the variation of the wavelength; and the analysis device determines the vibration amplitude and/or the vibration frequency of the base 1 or the end 2 of each fiber grating vibration sensing component based on the electrical signal.

Optionally, there are multiple fiber grating vibration sensing components, such as 60, and are divided into multiple groups, such as 3 groups, 20 in each group, the light source is a broadband light source, and there are multiple optical cables, such as 3, need It should be noted that the number of fiber grating vibration sensing components and the number of groups are not limited thereto. Each optical cable guides the light emitted by the broadband light source to the fiber grating of each fiber grating vibration sensing component in a corresponding fiber grating vibration sensing component group so as to connect the fiber gratings in the group in series, wherein each fiber The grating can reflect the light of the corresponding wavelength range in the light, and the corresponding wavelength ranges do not overlap with each other; the fiber grating demodulation instrument receives the light reflected back from each fiber grating and outputs an electric signal reflecting the change of the wavelength of the reflected light signal; and the analysis device determines the vibration amplitude and/or vibration frequency of each fiber grating vibration sensing component base 1 or end 2 based on the electrical signal. Advantageously, multiple groups of fiber grating vibration sensing components are arranged at intervals in sequence.

The present invention also relates to a vibration measurement system for rails, comprising: a signal capture module, a signal analysis module and an accident alarm module, wherein the signal capture module includes the above fiber grating vibration sensing component.

The present invention also relates to a method for measuring vibration, which uses the above-mentioned fiber grating vibration sensing component, and the method for measuring vibration includes the following steps:

Rigidly connecting the base 1 to the object under test 5;

Provide fiber grating demodulation equipment, fiber grating demodulation equipment including light source and optical cable;

providing light from the light source to the fiber grating using an optical fiber cable;

A fiber Bragg grating demodulation instrument receives light reflected back from the fiber Bragg grating and obtains an electrical signal reflecting a change in wavelength of the reflected light; and

The vibration amplitude and/or vibration frequency of the base 1 or end 2 of the fiber grating vibration sensing component is determined based on the electrical signal. Further, based on the vibration amplitude and/or vibration frequency of the base 1 or end 2 of the fiber grating vibration sensing component, the vibration amplitude and/or vibration frequency at the corresponding position of the object under test 5 can be determined.

In the vibration measuring system and the vibration measuring method of the present invention, the fiber grating vibration sensing components can be connected in series, and the number of fiber grating vibration sensing components that can be connected in series depends on the scanning wavelength range, channel quantity, and For the strength of the vibration signal to be measured, generally one channel can connect 20 FBG vibration sensing components in series, that is, one optical cable can connect 20 FBG vibration sensing components in series. The traditional electric sensor needs to have corresponding 20 cables. Moreover, in the vibration measuring system and vibration measuring method of the present invention, the transmission distance of the optical cable or optical fiber is long (up to several kilometers from the fiber grating vibration sensing part to the fiber grating demodulation instrument). In this way, compared with the prior art, the vibration measuring method and the vibration measuring system of the present invention have obvious advantages in terms of material cost and engineering construction.

In addition, fiber grating vibration sensing components have high sensitivity. For example, the traditional electrical sensor can basically measure to the order of 10 ^-6 power in the case of adding an amplifier, while the most basic wavelength change of the fiber grating sensing component is the 10 ^-9 power, which is the sensitivity of the traditional electrical sensor 1000 times.

Fiber grating vibration sensing components can be applied to the working environment of high magnetic field and electric field, which is unmatched by electric sensors. In addition, fiber grating vibration sensing components have good temperature resistance (the upper limit of working temperature can reach 400°C-600°C), and strong reusability.

While embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by The appended claims and their equivalents are defined.

Claims (15)

1. A fiber grating vibration sensing component, comprising: base; an end portion constituting a seismic mass; a cantilever beam connected between the base and the end, the cantilever beam constituting a vibration amplification arm; and An optical fiber grating strain gauge, the two ends of the optical fiber grating strain gauge are respectively fixed on the base and the end, and are used to detect the strain of the cantilever beam, It is characterized by: The upper surface of the base and/or the upper surface of the end is higher than the upper surface of the vibration amplification arm, and the two ends of the fiber grating strain gauge are respectively fixed on the upper surface of the base and the upper surface of the end superior; The base, the end and the vibration amplifying arm are formed in one piece. 2 . The fiber grating vibration sensing component according to claim 1 , wherein the vibration amplifying arm is an equal-intensity strain beam. 3 . 3. The fiber grating vibration sensing component according to claim 1, characterized in that, The longitudinal section of the one piece has an opening in the shape of a small rectangle cut out from the upper right corner of the rectangle. 4. The fiber grating vibration sensing part according to claim 1, characterized in that, The longitudinal section of the one-piece has a rectangular opening. 5. The fiber grating vibration sensing component according to claim 1, characterized in that, The base is fixed directly or indirectly to the rail. 6. The fiber grating vibration sensing component according to claim 1, characterized in that, An additional mass is attached to the end for adjusting the total mass of the end. 7. A fiber grating vibration sensing device, comprising: The fiber grating vibration sensing component according to any one of claims 1-6; and A fiber grating demodulation instrument, the fiber grating demodulation instrument includes a light source and an optical cable, Wherein the optical cable guides the light emitted by the light source to the fiber grating of the fiber grating vibration sensing part; and the fiber grating demodulation instrument receives light reflected back from the fiber grating and outputs light reflecting the reflected back An electrical signal that changes in wavelength due to the strain. 8. A vibration measuring system, comprising: The fiber grating vibration sensing component according to any one of claims 1-6; Fiber Bragg grating demodulation instrument, the fiber Bragg grating demodulation instrument includes a light source and an optical cable, wherein the optical cable guides the light emitted by the light source to the fiber Bragg grating of the fiber Bragg grating vibration sensing component, and the fiber Bragg grating demodulation The tuner receives light reflected back from the fiber grating and outputs an electrical signal reflecting a change in wavelength of the reflected light; and Analyzing means for determining the vibration amplitude and/or the vibration frequency of the base or end of the fiber grating vibration sensing part based on the electrical signal. 9. The vibration measuring system according to claim 8, characterized in that, The vibration measuring system further includes an early warning device, which sends an alarm when the vibration amplitude of the base or end of the fiber grating vibration sensing part exceeds a predetermined amplitude and/or the vibration frequency is outside a predetermined frequency range. 10. The vibration measuring system according to claim 8, characterized in that, There are multiple fiber grating vibration sensing components, the light source is a broadband light source, An optical cable guides the light emitted by the broadband light source to the fiber gratings of each fiber grating vibration sensing component to connect the fiber gratings in series, wherein each fiber grating can reflect the light of the corresponding wavelength range in the light, and the corresponding The wavelength ranges do not overlap with each other; The fiber grating demodulation instrument receives light reflected back from each fiber grating and outputs an electrical signal reflecting a change in wavelength of the reflected light; and The analysis device determines the vibration amplitude and/or vibration frequency of the base or end of each fiber grating vibration sensing component based on the electrical signal. 11. The vibration measuring system according to claim 8, characterized in that, The fiber grating vibration sensing components are multiple and divided into multiple groups, the light source is a broadband light source, and there are multiple optical cables, Wherein each optical cable guides the light emitted by the broadband light source to the fiber grating of each fiber grating vibration sensing component in a corresponding fiber grating vibration sensing component group so as to connect the fiber gratings in the group in series, wherein each A fiber grating is capable of reflecting light of corresponding wavelength ranges in the light, and said corresponding wavelength ranges do not overlap with each other; The fiber grating demodulation instrument receives light reflected back from each fiber grating and outputs an electrical signal reflecting a change in wavelength of the reflected light; and The analysis device determines the vibration amplitude and/or vibration frequency of the base or end of each fiber grating vibration sensing component based on the electrical signal. 12. The vibration measuring system according to claim 11, characterized in that, The multiple groups of fiber grating vibration sensing components are arranged at intervals in sequence. 13. A rail vibration measurement system, comprising: a signal capture module, a signal analysis module and an accident alarm module, characterized in that the signal capture module comprises the fiber grating vibration sensor described in any one of claims 1 to 6 sensor parts. 14. A method for measuring vibration, which utilizes the fiber grating vibration sensing part described in any one of claims 1-6, said method for measuring vibration comprises the following steps: Rigidly connect the base to the object under test; An optical fiber grating demodulation instrument is provided, and the optical fiber grating demodulation instrument includes a light source and an optical cable; providing light from the light source to the fiber grating using an optical fiber cable; a fiber bragg grating demodulation instrument receiving light reflected back from the fiber grating and outputting an electrical signal reflecting a change in wavelength of the reflected light due to said strain; and The vibration amplitude and/or vibration frequency of the base or end of the fiber grating vibration sensing component is determined based on the electrical signal. 15. The vibration measuring method according to claim 14, further comprising the steps of: Based on the vibration amplitude and/or vibration frequency of the base or end of the fiber grating vibration sensing component, determine the vibration amplitude and/or vibration frequency at the corresponding position of the object to be tested.

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