Fiber grating vibration sensor with temperature self-compensation and preparation method

Abstract

The application relates to a fiber grating vibration sensor with temperature self-compensation and a preparation method, wherein the sensor comprises a mass block with a high thermal expansion coefficient, a base and an X-shaped flexible hinge with a low thermal expansion coefficient; the base is provided with a shell; the X-shaped flexible hinge is arranged between the mass block and the base; two ends of the X-shaped flexible hinge are connected with the mass block and the base respectively; an optical fiber grating for detecting vertical vibration is arranged on the same side end surface of the mass block and the base in the axial direction of the central axis; and the optical fiber grating is located between the mass block and the base and is applied with a prestress. The application offsets the center wavelength change amount of the optical fiber grating caused by the distance change due to the thermal expansion between the fixed point of the optical fiber grating and the temperature change, and the center wavelength change amount of the optical fiber grating caused by the stress, so that the center wavelength of the optical fiber grating is not affected by the temperature change, and the temperature self-compensation of the fiber grating vibration sensor is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber grating sensors, and in particular relates to a fiber grating vibration sensor with temperature self-compensation and a preparation method thereof. Background Art

[0002] The most significant advantage of fiber Bragg grating (FBG) sensors is their ability to modulate the wavelength of the measured physical quantity, so that the sensor output signal is not affected by light intensity, connecting fiber and coupler losses, or light source energy.

[0003] Vibration measurement is an important means of monitoring the safety of structures. However, fiber Bragg grating (FBG) vibration sensors face the problem of cross-sensitivity to temperature and strain during measurement. Specifically, the axial strain generated by the stress detected by the FBG vibration sensor causes the FBG center wavelength to drift. Fluctuations in the ambient temperature also cause the FBG center wavelength to drift, affecting the accuracy of the measured data. Furthermore, changes in ambient temperature can cause internal thermal stresses in the sensor structure to affect the sensor's structural dimensions and material elastic modulus, thereby affecting sensor performance and reducing measurement accuracy. Therefore, to reduce the temperature sensitivity of FBG vibration sensors, temperature-compensated packaging is necessary to minimize the impact of temperature changes on the FBG center wavelength.

[0004] Publication No. CN 110531110 A discloses a fiber Bragg grating (FBG) two-dimensional acceleration sensor based on a U-groove structure. This sensor utilizes two pairs of back-to-back U-grooves on the upper and lower sides of the central core body to achieve a design that converts the elastic body of the fiber Bragg grating (FBG) vibration sensor. Four fiber grooves are evenly spaced on the circumferential outer surfaces of the inertial body and the base. Four fiber Bragg gratings (FBGs) are prestressed and installed in these grooves. These four FBGs are positioned perpendicular to each other, facilitating the detection of vibrations in two perpendicular directions. The sensor utilizes the wavelength shift difference between the two FBGs as its output signal, thereby eliminating the influence of in-phase wavelength shifts caused by changes in the common ambient temperature on the measurement results, providing temperature compensation. However, this method is based on the ideal situation that the center wavelength shifts of the two fiber Bragg gratings caused by temperature changes are the same and synchronized with the temperature changes, so the differential output is theoretically close to zero. However, in actual applications, due to uncontrollable factors such as the glue thickness, the degree of glue curing, and whether the fiber Bragg grating is arranged along the main vibration direction during the packaging process, there will be differences in heat conduction between the fiber Bragg gratings fixed at different positions. Therefore, the center wavelength shifts of the two fiber Bragg gratings caused by temperature changes cannot be completely offset, resulting in its measurement results still not being accurate enough. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a fiber Bragg grating vibration sensor with temperature self-compensation and a preparation method. By offsetting the change in the center wavelength of the fiber Bragg grating caused by temperature changes with the change in the center wavelength of the fiber Bragg grating caused by stress generated by the distance change caused by thermal expansion between the fixed points of the fiber Bragg grating, the center wavelength of the fiber Bragg grating is not affected by temperature changes, thereby realizing temperature self-compensation of the fiber Bragg grating vibration sensor.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A fiber Bragg grating vibration sensor with temperature self-compensation includes a mass block with a high thermal expansion coefficient, a base, and an X-shaped flexible hinge with a low thermal expansion coefficient. The base is provided with a shell, which wraps the mass block and the X-shaped flexible hinge. The mass block and the base are arranged relative to each other with an upper and lower interval. The X-shaped flexible hinge is arranged between the mass block and the base, and the two ends of the X-shaped flexible hinge are respectively connected to the mass block and the base. A fiber Bragg grating is axially arranged on the same side periphery of the mass block and the base. The fiber Bragg grating is located between the mass block and the base and is prestressed for detecting vibrations in the vertical direction.

[0008] Furthermore, the X-shaped flexible hinge includes at least one pair, and the pair of X-shaped flexible hinges are arranged in parallel and spaced apart. The upper and lower ends of the X-shaped flexible hinge are respectively provided with bosses, and the lower end of the mass block and the upper end of the base are both provided with grooves, and the bosses are plugged into the corresponding grooves.

[0009] Furthermore, an upper optical fiber groove is axially arranged at the center axis of one side end face of the mass block, and a lower optical fiber groove is axially arranged at the center axis of one side end face of the base. The upper optical fiber groove and the lower optical fiber groove are coaxial, and the two end pigtails of the optical fiber grating are respectively fixed in the upper optical fiber groove and the lower optical fiber groove.

[0010] Furthermore, the boss is a column pin, the groove is a column hole, and the column pin and the corresponding column hole are interference fit.

[0011] Furthermore, the base is provided with a fiber hole that penetrates the lower optical fiber groove, and one end of the fiber grating pigtail passes through the fiber hole and extends out of the base.

[0012] Furthermore, the base includes an upper substrate and a lower substrate, the upper substrate is stacked on the lower substrate, and the outer periphery of the lower substrate extends beyond the outer periphery of the upper substrate.

[0013] Furthermore, the lower optical fiber groove is provided on the upper substrate, and the fiber hole is provided on the lower substrate and communicates with the lower optical fiber groove.

[0014] Furthermore, the mass block and the base are both made of aluminum alloy, and the X-shaped flexible hinge is made of Invar.

[0015] Furthermore, the pigtails at both ends of the fiber grating are fixed in the upper fiber groove and the lower fiber groove respectively by epoxy resin, and at least the pigtail located in the epoxy resin is a bare fiber.

[0016] The present invention also provides a method for preparing a fiber Bragg grating vibration sensor with temperature self-compensation, comprising the following steps:

[0017] Step S1: performing interference fit heat-shrink assembly on the X-shaped flexible hinge, mass block, and base;

[0018] Step S2: After applying a certain prestress to the fiber Bragg grating, the fiber pigtails at both ends of the fiber Bragg grating are fixed to the periphery of the mass block and the periphery of the base, respectively, the fiber Bragg grating is located between the mass block and the base, and the fiber pigtail at at least one end of the fiber Bragg grating extends out of the base;

[0019] Step S3: Assembling a shell on the base.

[0020] The present invention adopts the above technical solution, which has the following advantages and effects:

[0021] The present invention provides a fiber Bragg grating (FBG) vibration sensor with temperature self-compensation and a preparation method, which are intended to solve the problem of strain and temperature cross-sensitivity that occurs when the fiber Bragg grating (FBG) vibration sensor performs vibration measurement. The present invention fixes the fiber Bragg grating (FBG) between a mass block with a high thermal expansion coefficient and a base, and connects the mass block and the base via an X-shaped flexible hinge with a low thermal expansion coefficient. By selecting the dimensions of the mass block, the base, and the thermal expansion coefficients of the materials of the X-shaped flexible hinge, the change in the center wavelength of the fiber Bragg grating (FBG) caused by temperature changes is offset by the change in the center wavelength of the fiber Bragg grating (FBG) caused by stress generated by distance changes due to thermal expansion between the fiber Bragg grating fixing points. Ultimately, the center wavelength of the fiber Bragg grating is not affected by temperature changes, thereby achieving temperature self-compensation of the fiber Bragg grating vibration sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a schematic structural diagram of a fiber Bragg grating vibration sensor with temperature self-compensation according to the present invention.

[0023] Figure 2 It is a schematic diagram of the base structure of the present invention.

[0024] Figure 3 Schematic diagram of the mass block structure of the present invention.

[0025] Figure 4 It is a schematic diagram of the X-shaped flexible hinge structure of the present invention.

[0026] Figure 5 Schematic diagram of the temperature compensation principle of the present invention.

[0027] Figure 6 Schematic diagram of thermal deformation decomposition based on the temperature compensation principle of the invention.

[0028] Figure 7 Schematic diagram of the temperature compensation structure of the fiber Bragg grating vibration sensor of the present invention.

[0029] Among them, 1-shell, 2-mass block, 3-X-shaped flexible hinge, 4-fiber Bragg grating, 5-base, 6-bolt, 201-upper column hole, 202-upper fiber groove, 301-pin, 501-lower base plate, 502-upper base plate, 503-fiber hole, 504-counterbore, 505-lower column hole, 506-lower fiber groove. DETAILED DESCRIPTION

[0030] The following will be described in detail with reference to the accompanying drawings to provide a clearer understanding of the objectives, features and advantages of the present invention. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0031] like Figures 1-4 As shown. The present invention provides a fiber Bragg grating vibration sensor with temperature self-compensation, comprising a mass block 2, a base 5 and an X-shaped flexible hinge 3. A shell 1 is provided on the base 5, and the shell 1 wraps the mass block 2 and the X-shaped flexible hinge 3. The mass block 2 and the base 5 are spaced apart from each other in the upper and lower directions. The X-shaped flexible hinge 3 is arranged between the mass block 2 and the base 5, and the two ends of the X-shaped flexible hinge 3 are respectively connected to the mass block 2 and the base 5. A fiber Bragg grating 4 is axially provided on the same side periphery of the mass block 2 and the base 5. The fiber Bragg grating 4 is located between the mass block 2 and the base 5 and is prestressed. The fiber Bragg grating 4 is used to detect vibrations in the vertical direction. The fiber Bragg grating 4 is bonded and fixed to the mass block 2 and the base 5 at both ends by applying a certain prestress. One end of the fiber Bragg grating passes through the base 5 and is connected to the demodulator.

[0032] Specifically, the mass block 2 and base 5 are made of materials with high thermal expansion coefficients, such as aluminum alloy or beryllium bronze. The mass block 2 is a rectangular parallelepiped structure, and the base 5 is a plate-like structure. The X-shaped flexible hinge 3 is made of materials with low thermal expansion coefficients, such as quartz or Invar.

[0033] The X-shaped flexible hinge 3 is an X-shaped structural member, positioned between the mass 2 and the base 5, integrally connecting them. The bottom of the housing 1 is open, with screw holes disposed around its perimeter. Countersunk holes 504 are disposed around the edges of the upper end of the base 5. Bolts 6 pass through the countersunk holes 504 and threadably engage with corresponding screw holes to secure the housing 1 and base 5.

[0034] Furthermore, the X-shaped flexible hinge 3 includes at least one pair of X-shaped flexible hinges 3, which are arranged in parallel and spaced apart. The upper and lower ends of the X-shaped flexible hinge 3 are respectively provided with bosses. The lower end of the mass block 2 and the upper end of the base 5 are both provided with grooves. The bosses are plugged into the corresponding grooves to securely connect the X-shaped flexible hinge 3 to the mass block 2 and the base 5. The bosses and grooves are connected by a shrink-fit interference fit to achieve a reliable and stable connection between the X-shaped flexible hinge 3, the mass block 2, and the base 5.

[0035] Specifically, in order to ensure the stability of the mass block 2 and the base 5 while reducing the torsional stiffness and lateral interference of the X-shaped flexible hinge 3, multiple X-shaped flexible hinges 3 can be provided, and the multiple X-shaped flexible hinges 3 are parallel and spaced apart from each other.

[0036] As a preferred embodiment, the present invention includes a pair of X-shaped flexible hinges 3, which are arranged in parallel and spaced apart between the mass block 2 and the base 5. The lower end surface of the mass block 2 and the upper end surface of the base 5 are both provided with four grooves, and the upper and lower end surfaces of the X-shaped flexible hinges 3 are both provided with bosses. The four bosses on the upper end surfaces of the pair of X-shaped flexible hinges 3 are plugged into and matched with the four grooves on the lower end surface of the mass block 2, and the four bosses on the lower end surfaces of the pair of X-shaped flexible hinges 3 are plugged into and matched with the four grooves on the upper end surface of the base 5.

[0037] Furthermore, in order to facilitate the fixation of the optical fiber Bragg grating 4, an upper optical fiber groove 202 is axially arranged at the center axis of the end face of one side of the mass block 2, and a lower optical fiber groove 506 is axially arranged at the center axis of the end face of one side of the base 5. The upper optical fiber groove 202 and the lower optical fiber groove 506 are coaxial, and the pigtails at both ends of the optical fiber Bragg grating 4 are respectively bonded and fixed in the upper optical fiber groove 202 and the lower optical fiber groove 506.

[0038] Specifically, the upper fiber groove 202 and the lower fiber groove 506 are respectively located on the same side of the mass block 2 and the base 5 and are relatively coaxially connected vertically. The cross-sections of the upper fiber groove 202 and the lower fiber groove 506 are preferably U-shaped structures.

[0039] Furthermore, the boss is a column pin 301, the groove is a column hole, and the column pin 301 and the corresponding column hole are interference fit.

[0040] Specifically, the pins 301 are preferably cylindrical pins, and the holes are preferably cylindrical holes. The pins 301 are integrally formed at the upper and lower ends of the X-shaped flexible hinge 3. The holes on the lower surface of the mass 2 are upper holes 201, which mate with the four pins 301 on the upper ends of the pair of X-shaped flexible hinges 3 in a hole-and-shaft connection. The holes on the upper surface of the base 5 are lower holes 505, which engage with the four pins 301 on the lower ends of the pair of X-shaped flexible hinges 3.

[0041] Furthermore, the base 5 is provided with a fiber hole 503 that passes through the lower fiber groove 506. The pigtail of the fiber grating 4 passes through the fiber hole 503 and extends out of the lower end surface of the base 5. The extended pigtail is connected to the fiber jumper and then connected to the demodulator.

[0042] Furthermore, the base 5 includes an upper substrate 502 and a lower substrate 501 . The upper substrate 502 is stacked on the lower substrate 501 , and the periphery of the lower substrate 501 extends beyond the periphery of the upper substrate 502 .

[0043] Specifically, the outer peripheral size of the upper substrate 502 is smaller than the outer peripheral size of the lower substrate 501. The upper substrate 502 and the lower substrate 501 are integrally arranged. When the upper substrate 502 is arranged on the lower substrate 501, the outer peripheral surface of the upper substrate 502 is coaxial with the outer peripheral surface of the lower substrate 501. The shell 1 is arranged on the lower substrate 501 to surround the upper substrate 502.

[0044] Furthermore, the lower fiber slot 506 is axially arranged on the central axis of one end surface of the upper substrate 502, and the fiber hole 503 is arranged on the lower substrate 501 and passes through the lower fiber slot 506. One end of the fiber grating 4 passes through the lower fiber slot 506 through the fiber hole 503 and then extends out of the lower substrate 501.

[0045] Furthermore, the pigtails at both ends of the fiber grating 4 are respectively fixed in the upper fiber groove 202 and the lower fiber groove 506 by epoxy resin, and at least the pigtail located in the epoxy resin is a bare fiber.

[0046] Specifically, in order to prevent the prestress on the fiber grating 4 from disappearing, the fiber pigtail bonded and fixed in the epoxy resin is a bare fiber segment. By bonding and fixing the bare fiber segment, the fiber pigtail coating can be prevented from delamination and the prestress pre-applied to the fiber grating 4 can be released.

[0047] Furthermore, in order to prevent the overflow of epoxy resin, a glue dot groove is provided at the bottom of the upper optical fiber groove 202 and the lower optical fiber groove 506 for bonding and fixing the pigtail. By filling the epoxy resin into the glue dot groove at the bottom of the upper optical fiber groove 202 and the lower optical fiber groove 506, the epoxy resin can be prevented from overflowing along the upper optical fiber groove 202 or the lower optical fiber groove 506 when bonding and fixing the pigtail.

[0048] like Figure 5 、 Figure 6 The temperature compensation principle of the fiber Bragg grating vibration sensor of the present invention is as follows: the X-shaped flexible hinge 3 of the fiber Bragg grating vibration sensor is simplified into a hypotenuse component, and the mass block 2 and the base 5 are simplified into a base component.

[0049] With the X-axis as the horizontal direction and the Y-axis as the vertical direction, the length of the hypotenuse member is set to L1, the thermal deformation after heating is dL1, the length of the hypotenuse member after heating is L1+dL1, the length of the base member is L2, the thermal deformation after heating is dL2, the length of the base member after heating is L2+dL2, the thermal expansion coefficients of the mass block 2 and the base 5 are both α1, the thermal expansion coefficient of the X-shaped flexible hinge 3 is α2, the distance between the top of the base 5 and the bottom of the mass block 2 in the base member is h, the angle between the base member and the hypotenuse member when not rotated is θ, the relative rotation angle of the base member and the hypotenuse member caused by the thermal expansion of the hypotenuse member is dθ, and the angle between the base member and the hypotenuse member after heating is θ+dθ.

[0050] When the ambient temperature rises, the base member expands horizontally due to the heat, reducing the distance h between the top of the base 5 and the bottom of the mass block 2. The thermal expansion of the hypotenuse member causes the base member and the hypotenuse member to rotate relative to each other, increasing the distance h between the top of the base 5 and the bottom of the mass block 2. At this time, the temperature-sensitive change in the distance between the top of the base 5 and the bottom of the mass block 2 is dh, and the axial strain of the fiber Bragg grating 4 is for: ;(1)

[0051] When the ambient temperature changes, the thermal deformation of the bevel member can be Decomposed into the XY axes of the rectangular coordinate system, the thermal deformation of the bevel component is The vector expression of is: ;(2)

[0052] In formula (2), is the unit vector on the X axis, is the unit vector on the Y axis, is the angle between the bevel member and the base member;

[0053] The change in ambient temperature of the beveled edge component is Thermal deformation under Expressed as: ;(3)

[0054] In formula (3), for Coefficient of thermal expansion in the direction (transverse), for Coefficient of thermal expansion in the longitudinal direction.

[0055] At this time, the thermal expansion coefficient of the oblique side member is defined in the rectangular coordinate system as for: ;(4)

[0056] Combining formulas (2)-(4), we can get: ;(5)

[0057] The longitudinal thermal expansion coefficient of the bevel component (i.e., X-shaped flexible hinge 3) can be obtained by sorting out for: ;(6)

[0058] Since the fiber Bragg grating 4 can directly measure the strain and temperature, the central wavelength of the fiber Bragg grating 4 and the central wavelength drift of the fiber Bragg grating Expressed as: ;(7)

[0059] In formula (7), represents the strain sensitivity of the fiber Bragg grating 4 measured, is the measured temperature sensitivity of fiber Bragg grating 4, is the effective elastic-optical coefficient of the optical fiber, is the thermo-optical coefficient of the optical fiber, is the thermal expansion coefficient of the optical fiber.

[0060] In order to achieve the temperature compensation effect, the fiber Bragg grating vibration sensor should be subjected to only the change of ambient temperature. Under the influence of is 0, which satisfies: ;(8)

[0061] The strain portion of the center wavelength drift of the fiber Bragg grating 4 is the center wavelength change caused by the negative displacement between two fixed points of the fiber Bragg grating 4 under the influence of temperature and compression of the fiber Bragg grating 4 .

[0062] like Figure 7 As shown. When the ambient temperature changes , the length change of the X-type flexible hinge 3 in the Y-axis direction for: ;(9)

[0063] In formula (9), is the torsional radius of the X-shaped flexible hinge 3, is the half angle between the two straight beams of the X-shaped flexible hinge 3, and They are complementary angles.

[0064] At this time, the equivalent effect variable generated by the axial compression of the fiber Bragg grating 4 is for: ;(10)

[0065] At this time, the overall thermal expansion coefficient of the compensation part between the two fixed points of the fiber Bragg grating can be obtained from formula (10), that is, the longitudinal thermal expansion coefficient of the X-shaped flexible hinge 3 for: ;(11)

[0066] In formula (11), is the distance between the two fixed points of the fiber Bragg grating. Based on formula (11), by selecting appropriate sizes and thermal expansion coefficients of the mass block 2, base 5, and X-shaped flexible hinge 3, the central wavelength of the fiber Bragg grating 4 is not affected by temperature changes, thus achieving temperature self-compensation of the fiber Bragg grating vibration sensor.

[0067] To verify the feasibility of temperature compensation for a fiber Bragg grating (FBG) vibration sensor, the present invention used the simulation software Ansys Workbench to perform steady-state thermal simulation on the FBG vibration sensor model. During the simulation, the initial ambient temperature for the steady-state thermal simulation was set to 22°C, and an operating temperature of 42°C was applied to the FBG vibration sensor model. This temperature environment was then incorporated into the statics analysis module, revealing the thermal deformation of the FBG vibration sensor model under a 20°C temperature rise. Furthermore, the boundary condition for the solution was set to a frictionless bottom of the FBG vibration sensor model. After applying a weak spring condition, the relative displacement of the FBG vibration sensor model at the ends of the FBG was calculated to obtain the temperature compensation results for the FBG vibration sensor model.

[0068] Through comparative simulation, the temperature drift of the fiber Bragg grating vibration sensor of the present invention can reach 0.64 pm / °C, which is effectively reduced compared with the temperature drift of 10 pm / °C of the traditional single-mode fiber Bragg grating.

[0069] When the fiber Bragg grating vibration sensor provided by the present invention is measured, the fiber Bragg grating vibration sensor is fixed on the surface of the object to be measured, and the bottom surface of the fiber Bragg grating vibration sensor is kept in a vertical position. When the fiber Bragg grating vibration sensor is subjected to external vibration excitation, under the action of inertia, the mass block 2 of the fiber Bragg grating vibration sensor rotates slightly around the center of the X-shaped flexible hinge 3. The vertical displacement generated by the mass block 2 causes the fiber Bragg grating 4 to stretch or compress, causing the center wavelength of the fiber Bragg grating 4 to drift. The drift of the center wavelength of the fiber Bragg grating 4 is measured by a demodulator, thereby establishing a corresponding relationship between the external excitation acceleration and the drift of the center wavelength of the fiber Bragg grating, thereby obtaining vibration information of the vibration acceleration.

[0070] The present invention also provides a method for preparing a fiber Bragg grating vibration sensor with temperature self-compensation, comprising the following steps:

[0071] Step S1: performing interference fit shrinkage on the X-shaped flexible hinge 3, the mass block 2 and the base 5.

[0072] Specifically, during the heat-fitting assembly, first clean the oil and dust on the mating surfaces of the base 5, the mass block 2 and the X-shaped flexible hinge 3; then heat the base 5 and the mass block 2 for 15-20 minutes, so that the temperature of both is raised to about 1000°C, and keep warm for 10 minutes. After eliminating the interference between the two and the upper and lower ends of the X-shaped flexible hinge 3, heat-fitting can be performed immediately.

[0073] Step S2: After applying a certain prestress to the fiber Bragg grating 4, use epoxy resin to fix the pigtails at both ends of the fiber Bragg grating 4 in the upper fiber groove 202 on the periphery of the mass block 2 and the lower fiber groove 506 on the periphery of the base 5 respectively. The fiber Bragg grating 4 is located between the mass block 2 and the base 5, and at least one end of the pigtail of the fiber Bragg grating 4 extends out of the base 5.

[0074] Step S3: Assembling the housing 1 on the base 5 ; during assembly, the housing 1 is fixed to the base 5 by bolts 6 .

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A fiber Bragg grating vibration sensor with temperature self-compensation, characterized in that: The invention comprises a mass block (2) with a high thermal expansion coefficient, a base (5) and an X-shaped flexible hinge (3) with a low thermal expansion coefficient, wherein a shell (1) is provided on the base (5), and the shell (1) wraps the mass block (2) and the X-shaped flexible hinge (3), the mass block (2) and the base (5) are arranged relative to each other with an upper and lower interval, the X-shaped flexible hinge (3) is arranged between the mass block (2) and the base (5), and the two ends of the X-shaped flexible hinge (3) are respectively connected to the mass block (2) and the base (5); a fiber Bragg grating (4) is axially provided on the same side periphery of the mass block (2) and the base (5), and the fiber Bragg grating (4) is located between the mass block (2) and the base (5) and is applied with prestress, and is used to detect vibration in the vertical direction; The X-shaped flexible hinge (3) comprises at least one pair, wherein the pair of X-shaped flexible hinges (3) are arranged in parallel and spaced apart, and the upper and lower ends of the X-shaped flexible hinge (3) are respectively provided with bosses, and the lower end of the mass block (2) and the upper end of the base (5) are both provided with grooves, and the bosses are plug-fitted into the corresponding grooves; An upper optical fiber groove (202) is axially arranged at the center axis of one end surface of the mass block (2), and a lower optical fiber groove (506) is axially arranged at the center axis of one end surface of the base (5). The upper optical fiber groove (202) and the lower optical fiber groove (506) are coaxial, and the pigtails at both ends of the optical fiber grating (4) are fixed in the upper optical fiber groove (202) and the lower optical fiber groove (506), respectively.

2. The fiber Bragg grating vibration sensor with temperature self-compensation according to claim 1, characterized in that: The boss is a column pin (301), the groove is a column hole, and the column pin (301) and the corresponding column hole are interference fit.

3. The fiber Bragg grating vibration sensor with temperature self-compensation according to claim 1, characterized in that: The base (5) is provided with a fiber hole (503) that is in communication with the lower optical fiber groove (506), and a pigtail at one end of the optical fiber grating (4) passes through the fiber hole (503) and extends out of the base (5).

4. The fiber Bragg grating vibration sensor with temperature self-compensation according to claim 3, characterized in that: The base (5) comprises an upper substrate (502) and a lower substrate (501), wherein the upper substrate (502) is stacked on the lower substrate (501), and the periphery of the lower substrate (501) extends beyond the periphery of the upper substrate (502).

5. The fiber Bragg grating vibration sensor with temperature self-compensation according to claim 4, characterized in that: The lower optical fiber groove (506) is arranged on the upper substrate (502), and the fiber hole (503) is arranged on the lower substrate (501) and is connected to the lower optical fiber groove (506).

6. The fiber Bragg grating vibration sensor with temperature self-compensation according to claim 5, characterized in that: The mass block (2) and the base (5) are both made of aluminum alloy, and the X-shaped flexible hinge (3) is made of Invar.

7. The fiber Bragg grating vibration sensor with temperature self-compensation according to claim 6, characterized in that: The pigtails at both ends of the fiber grating (4) are fixed in the upper fiber groove (202) and the lower fiber groove (506) respectively by epoxy resin, and at least the pigtail located in the epoxy resin is a bare fiber.

8. A method for preparing a fiber Bragg grating vibration sensor with temperature self-compensation according to any one of claims 1 to 7, characterized in that: The following steps are included: Step S1: performing interference fit heat-fitting on the X-shaped flexible hinge (3), the mass block (2) and the base (5); Step S2: After applying a certain prestress to the optical fiber Bragg grating (4), the pigtails at both ends of the optical fiber Bragg grating (4) are fixed to the periphery of the mass block (2) and the periphery of the base (5), respectively, the optical fiber Bragg grating (4) is located between the mass block (2) and the base (5), and the pigtail at at least one end of the optical fiber Bragg grating (4) extends out of the base (5); Step S3: Assembling the housing (1) on the base (5).

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