CN111879969A - Medium-high frequency elliptical hinge double-fiber grating acceleration sensor and measurement method - Google Patents
Medium-high frequency elliptical hinge double-fiber grating acceleration sensor and measurement method Download PDFInfo
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- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/03—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses by using non-electrical means
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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- G—PHYSICS
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- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
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Abstract
The utility model provides a middle and high frequency elliptical hinge double fiber bragg grating acceleration transducer and a measuring method, comprising: the device comprises an elliptical hinge, a fixed bracket and a mass block; one end of the elliptical hinge is fixedly connected with the fixed support, and the other end of the elliptical hinge is connected to the mass block; the upper and lower surfaces of the fixed support and the mass block are respectively on the same plane, and fiber gratings are respectively stuck between the fixed support and the mass block on the same plane and right above and right below the elliptical hinge. The medium-high frequency double FBG acceleration sensor based on the elliptical hinge utilizes the advantage of large motion range of the elliptical hinge on the premise of ensuring high precision[12]The sensitivity of the sensor is improved, and the reflected wavelength is demodulated by adopting a difference method, so that the aim of multiplying the sensitivity is fulfilled.
Description
Technical Field
The disclosure belongs to the technical field of acceleration sensors, and particularly relates to a medium-high frequency elliptical hinge double-fiber grating acceleration sensor and a measurement method.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The construction of infrastructures such as high-speed rails and viaducts is gradually promoted, but the high-frequency vibration in railways and bridges seriously affects the structural health. Acceleration is one of the parameters used to describe the vibration of an object, and the vibration of a large structure can be reflected by measuring the acceleration. Compared with the traditional electromechanical acceleration sensor, the Fiber Bragg Grating (FBG) acceleration sensor has the advantages of high measurement sensitivity, insensitivity to electromagnetism, distributable measurement and the like, and is very suitable for monitoring medium-high frequency vibration of a large structure.
The medium-high frequency vibration is a main cause of the degradation of large structures such as bridges and tunnels, and the acquisition of the vibration frequency of an object by using an optical sensor is an important means for monitoring the high-frequency vibration of the large structures. In recent years, with the continuous development of the FBG sensing technology, the FBG acceleration sensor becomes a brand new research direction and is widely applied to the fields of earthquake monitoring, petrochemical industry, national defense safety, health monitoring of large engineering and infrastructure, and the like. Wangmanlong et al developed an optical fiber grating acceleration sensor with a double cantilever beams of equal strength, utilized ANSYS to determine the optimal parameters of the sensor, and realized the real-time monitoring of low-frequency signals below 50Hz with the sensitivity of 20.85pm/m.s-2. The cantilever beam type fiber grating vibration sensor is developed by Jia Zhen an et al, the resonant frequency of the sensor is 90Hz, the flat area is 10-50Hz, and the sensitivity of the sensor is 121pm/g2. OmPrakash et al have designed a novel two L cantilever's optic fibre bragg grating acceleration sensor, compare with single L cantilever beam formula fiber bragg grating acceleration sensor, and this design has not only increased sensitivity, has realized temperature self-compensation moreover, and the sensitivity of sensor is 406.7pm liveg. Guti é rrez N et al reported a fiber grating acceleration sensor based on a hexagonal hollow cylinder, which is characterized by miniaturization and light weight, but this design reduces the sensitivity of the sensor, which was experimentally verified to be only 19.65 pm/g.
In addition, one of the characteristics of the medium-high frequency sensor is that the frequency and the sensitivity are in inverse proportion, the early sensor of the type does not measure specific sensitivity due to the objective conditions and the insufficient precision of demodulation equipment at the time, and the sensitivity of the medium-high frequency fiber grating acceleration sensor reported in recent years is generally not high. The research on the fiber bragg grating acceleration sensor is mostly concentrated in the medium-low frequency range, and the research on the medium-high frequency fiber bragg grating acceleration sensor is relatively less.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a medium-high frequency elliptical hinge double-fiber grating acceleration sensor, which utilizes the advantage of large motion range of an elliptical hinge to improve the sensitivity of the sensor on the premise of ensuring high precision.
In order to achieve the above object, one or more embodiments of the present disclosure provide the following technical solutions:
in a first aspect, a medium-high frequency elliptical hinge double fiber grating acceleration sensor is disclosed, comprising: the device comprises an elliptical hinge, a fixed bracket and a mass block;
one end of the elliptical hinge is fixedly connected with the fixed support, and the other end of the elliptical hinge is connected to the mass block;
the upper and lower surfaces of the fixed support and the mass block are respectively on the same plane, and fiber gratings are respectively stuck between the fixed support and the mass block on the same plane and right above and right below the elliptical hinge.
The elliptical hinge, the fixed support and the mass block are directly cut out from the same metal material. The position relation is shown in figure 1, and the three materials are the same and are all made of spring steel. The fixing bracket plays a role of fixing the sensor and pasting the optical fiber, and the elliptical hinge is used as an elastic element. The mass acts to provide inertia in newton's third law.
In a second aspect, a method for measuring a medium-high frequency elliptical hinge double fiber bragg grating acceleration sensor is disclosed, which comprises the following steps:
when the fiber grating vibrates, the mass block rotates by taking the mass point of the elliptical hinge as the center under the action of inertia force, and simultaneously drives the upper fiber grating and the lower fiber grating to generate telescopic deformation, so that the reflection wavelength of the fiber grating is caused to drift;
at the same moment, one fiber grating is stretched, the other fiber grating is contracted, and the reflection wavelengths of the two fiber gratings are differenced to obtain a wavelength drift amount;
and demodulating the change condition of the central wavelength to obtain the relation between the change quantity of the central wavelength, namely the wavelength drift quantity and the acceleration.
Specifically, the sensor measures the amount of wavelength shift generated by the FBG under the influence of the vibration signal. A measurement step: the sensor is fixed on a vibration table, and the upper FBG and the lower FBG are connected to a wavelength demodulator and a data acquisition unit at the same time. When the vibration table vibrates, the wavelength demodulator demodulates the wavelength at each moment, and data are input into a computer through data acquisition.
Data processing: firstly, preprocessing the collected data to remove gross errors. And then, calculating the peak-to-peak value of the wavelength drift by using MATLAB software to obtain the sensitivity of the single FBG. And finally, finding out the wavelength drift amount under the double FBGs by using the same method, and calculating to obtain the sensitivity of the double FBGs.
The above one or more technical solutions have the following beneficial effects:
according to the technical scheme, the medium-high frequency double FBG acceleration sensor based on the elliptical hinge utilizes the advantage of large motion range of the elliptical hinge to improve the sensitivity of the sensor on the premise of ensuring high precision, and the reflection wavelength is demodulated by adopting a difference method to achieve the purpose of sensitivity multiplication.
Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
FIG. 1 is a schematic diagram of a sensor configuration according to an embodiment of the disclosure;
FIG. 2 is a vibration model of a sensor structure according to an embodiment of the disclosure;
FIG. 3 is a graph showing the influence of the length semi-axis b and the length semi-axis c of the elliptical hinge on the sensitivity and the resonant frequency according to the embodiment of the disclosure;
FIG. 4 is a simulation analysis chart of a static stress simulation of a simulation example;
FIG. 5 is a simulation example modal simulation analysis diagram;
FIG. 6 is a simulation example harmonic response simulation analysis diagram;
FIG. 7 is a diagram of a sensor sensitivity calibration experiment system;
FIG. 8 is a graph of acceleration sensor time domain response;
figure 9 sensitivity line fit plot.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
The embodiment discloses a medium-high frequency double FBG acceleration sensor based on an elliptical hinge, which utilizes the advantage of large motion range of the elliptical hinge to improve the sensitivity of the sensor on the premise of ensuring high precision, and demodulates the reflection wavelength by adopting a difference method to achieve the purpose of sensitivity multiplication. Sensitivity and resonant frequency of the sensor are analyzed through a theoretical model of the sensor, and structural parameters of the sensor are optimized and subjected to simulation analysis by adopting MATLAB and ANSYS software to obtain the structural parameters of the sensor. And developing a sensor, and verifying and analyzing an experimental result through a sensor calibration experiment.
Specifically, the embodiment discloses a medium-high frequency elliptical hinge double-fiber grating acceleration sensor, which is shown in fig. 1 and comprises an elliptical hinge, two FBGs, a mass block and a fixing support.
Wherein, FBG pastes between quality piece and fixed bolster one on the other, and the both ends of FBG exert equal prestressing force when pasting to prevent to appear the chirp effect.
One end of the elliptic hinge is fixedly connected with the fixed bracket, and the other end of the elliptic hinge is connected to the mass block;
the upper and lower surfaces of the fixed support and the mass block are respectively on the same plane, and fiber gratings are respectively stuck between the fixed support and the mass block on the same plane and right above and right below the elliptical hinge.
The shift of the central wavelength of the FBG, i.e. the amount of wavelength shift and the strain, are closely related, and the relationship between the two can be expressed as
In the formula, PeFor effective elasto-optical coefficient, usually 0.15-0.22, Δ λBThe drift amount of the central wavelength of the fiber Bragg grating under the strain action is the axial strain generated by the fiber Bragg grating.
The structural dimensions and mechanical model of the sensor are shown in fig. 2. Taking one FBG as an example, the theoretical sensitivity of the sensor is analyzed. When acceleration with the magnitude of g and the upward direction is applied to the sensor in the vertical direction, the mass vibrates around the hinge as known from newton's third law of motion.
From the moment equilibrium equation, one can obtain
In the formula, m is the mass of the mass block, d is the distance from the mass center of the mass block to the center of the hinge, K is the elastic coefficient of the optical fiber, l is the elongation of the optical fiber, h is the height of the mass block, K is the rotational stiffness of the hinge, and theta is the rotational angle of the hinge.
The rotational stiffness of the hinge is
Wherein
Where E is the modulus of elasticity of the material, w is the thickness of the hinge, s is c/t, c is the minor axis of the elliptical hinge, and t is the minimum thickness between the hinges. The sensitivity S of the sensor is the ratio of the central wavelength variation Delta lambda of the fiber grating to the acceleration a, i.e.
In the formula, PeIs the coefficient of elasticity, λBIs the center wavelength of the grating and,ffor fiber strain,. DELTA.l is the elongation of the fiber. The above is the sensitivity analysis of a single FBG, because the double FBGs are symmetrically pasted one on top of the other, one FBG stretches and the other necessarily contracts at the same time. The change of the reflection wavelengths of the two FBGs is opposite, so that the reflection wavelengths of the two FBGs are differed to obtain the wavelength drift amount, and the obtained sensor sensitivity is 2 times of that of the single FBG acceleration sensor.
Sensor resonant frequency analysis:
another important parameter of the sensor is the resonant frequency F, which is closely related to the frequency range that the sensor is capable of measuring, in general, the higher the resonant frequency of the sensor, the larger the measurable frequency range of the sensor. The moment of inertia of the mass block rotating around the center of the hinge is set to be J, and the rotation angle of the elliptic hinge is set to be theta.
The resonant frequency of the system is
Wherein the moment of inertia J is
Influence of structural parameters on sensor performance:
as can be seen from the expressions (5) and (6), the grating length l of the FBG acceleration sensor of the two-point bonding type is related to the sensitivity only and is not related to the resonance frequency, and the sensitivity is higher as the fiber grating is shorter. In addition, the sensitivity and the resonant frequency of the sensor are closely related to the dimensions of the elliptical hinge, such as the major axis b, the minor axis c, the thickness t, and the like. The sensor is made of spring steel with the density of 7800kg/m3The elastic modulus is 2.1E11 Pa, the thickness of the sensor is 12mm, the elastic modulus of the optical fiber is 7.2E10 Pa, the effective elastic-optical coefficient is 0.22, the central wavelength of the optical fiber grating is 1553nm, and the length l is 5 mm.
Discussion sensitivity and resonant frequency vary with the major and minor semi-axes b, c at different hinge thicknesses t. When the mass m of the mass block is 18.72g, b, c ∈ (0,10) is mm, and the thicknesses t of the elliptical hinges are 0.2mm, 0.6mm and 1mm respectively, the sensitivity and the resonant frequency change are obtained as shown in fig. 3.
As can be seen from fig. 3, when the parameters of the elliptical hinge are changed, both the sensitivity and the resonant frequency of the sensor are changed. When the major semi-axis b of the elliptical hinge is increased, the sensitivity of the sensor is increased, and the resonant frequency is reduced; when the semi-minor axis c of the elliptical hinge is increased, the sensitivity of the sensor is reduced, and the resonant frequency is increased; as the thickness t of the elliptical hinge increases, the sensor sensitivity increases and the resonant frequency decreases. Therefore, the structural parameters of the elliptical hinge need to be further optimized to obtain the optimal sensitivity and resonant frequency.
Structural parameter optimization:
in order to obtain the optimal sensitivity and resonant frequency, an optimization tool box of MATLAB software is adopted to optimize the length half axis b, the short half axis c and the thickness t of the elliptical hinge chain of the sensor. First, simplifying u in the stiffness formula (3) of the hinge, and when s ∈ (1,7) in the formula (4), performing polynomial fitting on the parameter s by using MATLAB to obtain:
F(x)＝0.0003574x4-0.007678x3+0.06342x2-0.2615x+0.7126 (8)
the fitting determination coefficient and the mean square error of the formula (8) are respectively 0.9997 and 0.00124, the two values fully illustrate the rationality of data fitting, the formula (8) is taken into the formula (4), and parameter optimization is carried out by using MATLAB. Setting the sensitivity and the resonant frequency of the sensor as target parameters, taking the values of the major semi-axis b, the minor semi-axis c and the thickness t of the elliptical hinge as constraint conditions, establishing an optimization model by combining an MATLAB optimization tool box, and taking the size and the processing possibility of the sensor into consideration to obtain the optimization model as
MAX S (9)
From the optimization result, when the length semi-axis b of the elliptical hinge is 2.578mm, the short semi-axis c is 2.081mm, and the thickness t of the elliptical hinge is 0.7919mm, the optimal sensitivity and resonant frequency can be obtained. Considering the problem of machining precision, the final values of b, c and t are respectively 2.6mm, 2.1mm and 0.8 mm.
ANSYS simulation
And modeling the sensor by adopting the structural parameters obtained by the analysis and optimization, and importing the structural parameters into ANSYS for simulation analysis. Firstly, introducing a model into an ANSYS static stress simulation tool, applying fixed constraint to a fixed support of a sensor model, and applying standard earth gravity acceleration g (g is 9.8 m/s) to the whole sensor2) The strain cloud of the model is obtained as shown in fig. 4. It can be seen that the sensorThe deformation generated at the free end is the largest and gradually decreases towards the fixed end, and the maximum deformation amount at the free end is 0.56 μm.
Modal analysis was performed on the sensor model according to the static stress analysis result, and as shown in fig. 5, the obtained resonant frequencies of the first-order mode and the second-order mode were 764.82Hz and 5101.4Hz, respectively. As shown in fig. 5(a), the first-order mode is simple harmonic vibration, which indicates that the sensor model generates vibration along the Y-axis under the external excitation. As shown in fig. 5(b), the second-order mode is a rotational mode, which indicates that the sensor model rotates along the X-axis under the external excitation. The comparison of the modal data of each order shows that the difference between the resonant frequency of the first-order mode and the resonant frequency of the second-order mode is larger, which indicates that the cross coupling of the structural sensor is small, and the cross interference can be effectively reduced.
And finally, carrying out harmonic response analysis on the model, applying fixed constraint on a fixed support of the sensor model, and analyzing the system dynamic response of the sensor model under the action of sinusoidal loads with different frequencies. The set frequency variation was 0-900Hz, the step size was 10Hz, the sinusoidal load size was 2g, and the resulting sensor dynamic response is shown in fig. 6.
As can be seen from FIG. 6, the resonant frequency of the sensor is about 780Hz, and the curve is relatively flat below 500Hz, which is beneficial to the measurement of medium and high frequencies.
Sensor calibration experiment:
in order to ensure that the sensor has good performance below 500Hz, a sensitivity calibration experiment needs to be carried out on the acceleration sensor. The sensor sensitivity calibration experiment system mainly comprises a vibration testing system and a signal demodulation system, and is shown in fig. 7. The vibration test system comprises a vibration table, a signal generator, a signal amplifier and the like; the signal demodulation system comprises a wavelength demodulator, a computer and the like; the designed sensor base is tightly connected with the vibrating table through bolts. The reflected light wave of the FBG is transmitted to a demodulator through a transmission optical fiber, the information carried by the wavelength change of the light wave is demodulated, and the experimental environment temperature is 25 ℃.
Response characteristic analysis: in order to test the response characteristic of the sensor, the output frequency of the vibration table is set to 325Hz, and the output amplitude of the acceleration is set to 1g, so as to obtain a time domain curve of the output frequency corresponding to the response of the fiber grating acceleration sensor, as shown in fig. 8.
As can be seen from fig. 8, the sensor has a good output frequency response. At each moment, the central wavelength variation of the upper optical fiber and the central wavelength variation of the lower optical fiber of the fiber grating acceleration sensor are equal in magnitude and opposite in direction.
Sensor sensitivity linear analysis:
in the sensor sensitivity linear test, 160Hz and 325Hz are selected to apply sinusoidal excitation signals to the sensor, the test range of the acceleration is increased from 0.1g to 2.0g, and the step size is 0.1 g. The wavelength drift amount of the sensor under the same excitation frequency and different accelerations is measured, and a sensitivity fitting curve of the sensor is obtained by fitting the linear relation between the wavelength drift amount and the acceleration, as shown in fig. 9.
As can be seen from FIG. 9, the single fiber sensitivity was 40.83pm/g at a vibration frequency of 160Hz, and the coefficient R was determined by fitting20.9987, the dual fiber differential sensitivity of 90.91pm/g, and the coefficient R determined by fitting20.9988. When the vibration frequency is 325Hz, the single optical fiber sensitivity is 59.22pm/g, and the coefficient R is determined by fitting20.9956, dual fiber differential sensitivity of 132.53pm/g, and fitting to determine the coefficient R2＝0.9962。
And (3) analyzing an experimental result: the result of the sensitivity calibration experiment of the sensor is compared with the theoretical sensitivity value, and the error of 3 percent is found, but the requirement of engineering application can be met. The reason for the existence of the error is presumed: (1) in the theoretical analysis part, MATLAB software is adopted to carry out linear fitting on the formula (4), so that errors exist, and data selected in theoretical calculation are approximate values; (2) when the sensor is machined, machining errors exist in the elliptical hinge due to the reasons that machining equipment is insufficient in precision, the machining temperature is not controllable, and the like.
The embodiment of the disclosure provides a medium-high frequency acceleration sensor based on an elliptical hinge, and the optimized result is analyzed and verified through a sensor sensitivity calibration experiment. The experimental results show that the sensitivity is about 132pm/g, the measurable frequency range is 80-495Hz, and the resonance frequency of the sensor is about 780 Hz. In addition, experiments further verify that the double-optical-fiber differential demodulation method can improve the sensitivity of the sensor in multiples, and a new idea is provided for monitoring the medium-high frequency vibration of a large-scale structure.
When the sensor is in a static state, the upper fiber grating and the lower fiber grating are not stressed, so that the central wavelength of the optical fiber cannot be changed. When the sensor vibrates, the mass block rotates by taking the mass point of the elliptical hinge as the center under the action of inertia force, and meanwhile, the upper FBG and the lower FBG are driven to generate telescopic deformation, so that the reflection wavelength of the FBG is caused to drift. Finally, the relationship between the central wavelength variation, namely the wavelength drift amount, and the acceleration is obtained by demodulating the variation condition of the central wavelength.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (10)
1. A middle-high frequency elliptical hinge double-fiber grating acceleration sensor is characterized by comprising: the device comprises an elliptical hinge, a fixed bracket and a mass block;
one end of the elliptical hinge is fixedly connected with the fixed support, and the other end of the elliptical hinge is connected to the mass block;
the upper and lower surfaces of the fixed support and the mass block are respectively on the same plane, and fiber gratings are respectively stuck between the fixed support and the mass block on the same plane and right above and right below the elliptical hinge.
2. The medium-high frequency elliptical hinge dual-fiber grating acceleration sensor of claim 1, wherein both ends of the fiber grating are pre-stressed equally when adhered to prevent chirp.
3. The medium-high frequency elliptical hinge dual-fiber grating acceleration sensor according to claim 1, wherein in the fiber grating, one fiber grating is stretched and the other fiber grating is contracted at the same time, and the reflection wavelengths of the two fiber gratings are differenced to obtain the wavelength drift amount.
4. The medium-high frequency elliptical hinge dual-fiber grating acceleration sensor of claim 1, wherein the fiber grating wavelength shift is proportional to the axial strain produced by the fiber grating.
5. The medium-high frequency elliptical hinge dual-fiber grating acceleration sensor according to claim 1, wherein the sensor sensitivity is the ratio of the variation of the center wavelength of the fiber grating to the acceleration.
6. The medium-high frequency elliptical hinge dual-fiber grating acceleration sensor according to claim 1, wherein the sensor is made of spring steel, and the density, the elastic modulus, the thickness of the sensor, the elastic modulus and the effective elastic-optic coefficient of the optical fiber, the center wavelength of the optical fiber grating and the length of the optical fiber grating are selected based on the measurement accuracy.
7. The medium-high frequency elliptical hinge double-fiber grating acceleration sensor as claimed in claim 1, wherein the sensitivity and the resonant frequency of the sensor are set as target parameters, the values of the major half axis, the minor half axis and the thickness of the elliptical hinge are taken as constraint conditions to obtain an optimized model, and the optimized structural parameters of the sensor are obtained by solving based on the optimized model.
8. The medium-high frequency elliptical hinge double fiber bragg grating acceleration sensor of claim 7, wherein a sensor is modeled based on optimized structural parameters of the sensor, a fixed constraint is applied to a fixed support of a sensor model, a system dynamic response of the sensor model under the action of sinusoidal loads of different frequencies is obtained, and a resonant frequency of the sensor, which is beneficial to realizing medium-high frequency measurement, is obtained.
9. The method for measuring a medium-high frequency elliptical hinge double fiber bragg grating acceleration sensor according to any one of claims 1 to 8, comprising the following steps:
when the fiber grating vibrates, the mass block rotates by taking the mass point of the elliptical hinge as the center under the action of inertia force, and simultaneously drives the upper fiber grating and the lower fiber grating to generate telescopic deformation, so that the reflection wavelength of the fiber grating is caused to drift;
at the same moment, one fiber grating is stretched, the other fiber grating is contracted, and the reflection wavelengths of the two fiber gratings are differenced to obtain a wavelength drift amount;
and demodulating the change condition of the central wavelength to obtain the relation between the change quantity of the central wavelength, namely the wavelength drift quantity and the acceleration.
10. The sensor sensitivity calibration experiment system is characterized by comprising a vibration testing system and a signal demodulation system;
the vibration test system comprises a vibration table, a signal generator and a signal amplifier; the fixed support base of the acceleration sensor of any one of claims 1 to 8 is tightly connected with the vibration table through a bolt, and the signal generator amplifies the generated signal through a signal amplifier so that the vibration table drives the acceleration sensor to vibrate;
the signal demodulation system comprises a circulator and a wavelength demodulator; the reflected light wave of the acceleration sensor fiber bragg grating is transmitted to a wavelength demodulator through a transmission fiber intervention circulator, and information carried by the wavelength change of the light wave is demodulated.
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| CN114217092A (en) * | 2021-12-15 | 2022-03-22 | 武汉理工大学 | FBG acceleration sensor based on diaphragm and elliptical hinge |
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| CN114166333A (en) * | 2021-12-14 | 2022-03-11 | 武汉理工大学三亚科教创新园 | Device and method for measuring seabed vibration signals |
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| CN116499576A (en) * | 2023-06-27 | 2023-07-28 | 山东省计算中心（国家超级计算济南中心） | Fiber bragg grating vibration sensor and measuring method thereof |
| CN116499576B (en) * | 2023-06-27 | 2023-09-12 | 山东省计算中心（国家超级计算济南中心） | Fiber bragg grating vibration sensor and measuring method thereof |
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