CN218847395U - Rod type two-dimensional fiber grating vibration sensor - Google Patents
Rod type two-dimensional fiber grating vibration sensor Download PDFInfo
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- CN218847395U CN218847395U CN202222722484.3U CN202222722484U CN218847395U CN 218847395 U CN218847395 U CN 218847395U CN 202222722484 U CN202222722484 U CN 202222722484U CN 218847395 U CN218847395 U CN 218847395U
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Abstract
A rod-type two-dimensional fiber grating vibration sensor comprises a fiber grating, a rod-type sensitive structure, an inertia mass block and a fixed base, wherein two fiber gratings with similar wavelengths are engraved on the fiber grating; one end of the rod-shaped sensitive structure is embedded into the center of the inertial mass block, the other end of the rod-shaped sensitive structure is fixed on the base, the fiber bragg grating is fixed above the inertial mass block and the base, the fiber bragg grating is suspended between the inertial mass block and the base, and the fiber bragg grating is connected with an external demodulator. The utility model discloses can detect the vibration signal of two directions to can eliminate the influence that the temperature detected vibration signal.
Description
Technical Field
The utility model belongs to the technical field of the optical fiber sensing, in particular to bar type two dimension fiber grating vibration sensor.
Background
The fiber grating can detect various signals such as pressure, temperature, flow, humidity, vibration and the like. The fiber grating vibration sensor is an important research direction of the fiber grating sensor, and in recent years, scientific researchers have made many achievements in the direction. The fiber grating vibration sensor mainly comprises an elastic sensitive structure, an inertia mass block, a base and a fiber grating. The basic principle of the fiber grating-based vibration sensor is that when a vibration signal acts on the sensor, a mass block on the free end of a beam can generate displacement under the action of inertia, so that the fiber grating attached to the mass block is driven to be compressed or stretched, the central wavelength of the fiber grating is changed, and the drift of the central wavelength of the fiber grating is demodulated through a demodulation system, so that the detection of the vibration signal can be realized.
Most of the existing fiber bragg grating vibration sensors are cantilever beam type fiber bragg grating vibration sensors, and the cantilever beam type fiber bragg grating vibration sensors are only applied to detection of one-dimensional vibration signals and cannot eliminate the influence of temperature on the one-dimensional vibration signals.
SUMMERY OF THE UTILITY MODEL
In order to overcome the defects of the prior art, the utility model aims to provide a rod-type two-dimensional fiber grating vibration sensor can detect the vibration signals of two directions and can eliminate the influence of temperature on vibration signal detection.
In order to realize the purpose, the utility model discloses a technical scheme is:
a rod-type two-dimensional fiber grating vibration sensor comprises a fiber grating 2 with two similar wavelengths, a rod-type sensitive structure 4, an inertia mass block 3 and a fixed base 1;
one end of a rod-shaped sensitive structure 4 is embedded into the center of the inertial mass block 3, the other end of the rod-shaped sensitive structure is fixed on the base 1, the fiber bragg grating 2 is fixed above the inertial mass block 3 and the base 1, the fiber bragg grating 2 is suspended between the inertial mass block 3 and the base 1, and the fiber bragg grating 2 is connected with an external demodulator.
The rod-shaped sensitive structure 4 and the fixed base 1 are of an integrated structure.
The center of the inertia mass block 3 is provided with a square groove, the groove is matched with the cross section of the rod-shaped sensitive structure 4, and the rod-shaped sensitive structure 4 is embedded into the inertia mass block 3 to complete connection.
The upper and lower two positions of the fixed base 1 close to the 5mm position of the edge are optical fiber fixed points 5, grooves with the thickness of 0.5mm x 0.5mm are carved at the points for fixing the fiber grating 2, and the top surfaces of the inertia mass block 3 and the fixed bases 1 at the two sides are fixed by ultraviolet glue.
The difference between the central wavelengths of the two ends of the fiber grating 2 is 2nm.
The utility model has the advantages that:
1. the two-dimensional vibration signal is detected, the number of sensors can be reduced in a multi-component vibration signal detection system, and system miniaturization is facilitated.
2. The structure and the package are simple and reliable, no complex element combination exists between elements, and the realization is easy.
3. The grating with the central wavelength difference of 2nm at two ends is carved on one optical fiber, so that the sensitivity of the sensor is doubled, and the temperature compensation can be carried out.
4. With two-point packaging, chirp can be avoided.
Drawings
Fig. 1 is a structural view of a rod-type two-dimensional fiber grating 2 vibration sensor.
Fig. 2 is a schematic structural diagram of the present invention.
Fig. 3 is a schematic view of the structure of the inertial mass block of the present invention.
FIG. 4 is a schematic diagram of a vibration experiment apparatus system.
FIG. 5 is a schematic view of a system of a temperature experiment apparatus.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Referring to the attached drawings, the rod-type two-dimensional fiber grating 2 vibration sensor comprises a base 1, a rod-type sensitive structure 4 connected with the base 1, a fiber grating 2 with the central wavelength difference of 2nm at two ends, an inertia mass block 3 and a fiber fixing point 5.
Wherein the size of pole type sensitive structure 4 is 40mm x 4mm, and the size of inertia quality piece 3 is 10mm x 20mm, and base 1's thickness is 10mm, highly is 30mm, and length is 60mm, and the width is 80mm, and fiber grating 2's central wavelength is 1548nm and 1550nm respectively.
A detection method of a rod-type two-dimensional fiber grating vibration sensor comprises the following steps;
the vibration experiment device system is composed of an FBG dynamic demodulator, a signal generator (WS-5921), a power amplifier (GF-500W), a vibration table (JZ-40, beijing spectrum) and a computer, as shown in FIG. 4. When the fiber grating 2 is packaged, the optical fiber is fixedly packaged by ultraviolet glue after the optical fiber is applied with 1.5nm of prestress; after a fixed period of time, outputting a sine signal generated by the signal generator to a power amplifier, and controlling the frequency and the acceleration of an output signal of the vibration table through the power amplifier; the FBG vibration sensor is fixed on a vibration table, an optical fiber in the sensor is connected to a demodulator, and finally the demodulator and a computer are connected for reading the change of the FBG wavelength in real time.
When the vibration direction is up and down, the fiber gratings 2 on both sides of the inertial mass block 3 are in a stretching state, and when the vibration signal direction is left and right, one of the two gratings is in a stretching state and the other grating is in a compressing state. The wavelength drift of the fiber grating 2 is measured by a demodulator, so that the detection of the vibration signal is completed.
Temperature experimental apparatus system is as shown in fig. 5, comprises FBG developments demodulation appearance, electric heat blast air drying cabinet and computer, makes the ambient temperature around the sensor change through adjusting the incasement temperature, links to each other fiber grating 2 with the demodulation appearance, and the demodulation appearance is transmitted the computer after with the information demodulation that optic fibre transmitted, obtains FBG's central wavelength under certain temperature through demodulation software. The change of the central wavelength of the two gratings is subtracted, so that the sensor has better temperature compensation capability on temperature.
The utility model discloses the theory of operation is:
the utility model discloses utilize fiber grating 2 receiving the external sensing principle that meets an emergency back center wavelength drifts, under the excitation of external vibration signal, the inertial mass piece 3 of sensor produces the inertial force. Under the action of inertia force, the rod-shaped structure generates axial strain, so that the central wavelength of the fiber bragg grating 2 packaged on the rod-shaped structure is shifted, and the vibration signal is detected by detecting the change of the central wavelength through a demodulation system.
The rigidity of the designed rod-type two-dimensional fiber grating 2 vibration sensor can be obtained according to an elastic element rigidity formula as follows:
in the formula, h represents the width of the rod, l represents the length of the rod, and E represents the elastic modulus of the rod.
The elastic stiffness of the fiber can be expressed as:
in the formula, E f Is the Young's modulus of an optical fiber, A f L is the effective length of the fiber, which is the cross-sectional area of the fiber.
The equivalent mass M of the sensor is:
M＝m+0.45m 1
where m is the mass of the inertial mass 3, m 1 Is the mass of the rod.
When the vibration direction is along the Z direction, the natural frequency of the sensor is:
the sensitivity of the sensor is:
when the vibration direction is along the Y direction, the natural frequency of the sensor is:
the sensor sensitivity is:
Claims (5)
1. a rod-type two-dimensional fiber grating vibration sensor is characterized by comprising a fiber grating (2) with two similar wavelengths, a rod-type sensitive structure (4), an inertia mass block (3) and a fixed base (1);
one end of the rod-shaped sensitive structure (4) is embedded into the center of the inertial mass block (3), the other end of the rod-shaped sensitive structure is fixed on the base (1), the fiber bragg grating (2) is fixed above the inertial mass block (3) and the base (1), the fiber bragg grating (2) is suspended between the inertial mass block (3) and the base (1), and the fiber bragg grating (2) is connected with an external demodulator.
2. A rod-type two-dimensional fiber grating vibration sensor according to claim 1, wherein the rod-type sensitive structure (4) and the fixed base (1) are an integral structure.
3. The rod-type two-dimensional fiber grating vibration sensor according to claim 1, wherein the center of the inertial mass (3) has a square groove, the groove is matched with the cross section of the rod-type sensitive structure (4), and the rod-type sensitive structure (4) is embedded in the inertial mass (3) to complete connection.
4. The rod-type two-dimensional fiber grating vibration sensor according to claim 1, wherein the two positions of the upper and lower fixed bases (1) near the edge by 5mm are fiber fixed points (5) on which grooves of 0.5mm by 0.5mm are engraved for fixing the fiber grating (2), and the fiber is fixed by ultraviolet glue on the top surface of the inertial mass (3) and the top surfaces of the fixed bases (1) at the two sides.
5. The rod-type two-dimensional fiber grating vibration sensor according to claim 1, wherein the difference between the center wavelengths of the two ends of the fiber grating (2) is 2nm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222722484.3U CN218847395U (en) | 2022-10-17 | 2022-10-17 | Rod type two-dimensional fiber grating vibration sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222722484.3U CN218847395U (en) | 2022-10-17 | 2022-10-17 | Rod type two-dimensional fiber grating vibration sensor |
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| Publication Number | Publication Date |
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| CN218847395U true CN218847395U (en) | 2023-04-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202222722484.3U Active CN218847395U (en) | 2022-10-17 | 2022-10-17 | Rod type two-dimensional fiber grating vibration sensor |
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- 2022-10-17 CN CN202222722484.3U patent/CN218847395U/en active Active
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