CN219572964U - Fiber bragg grating strain sensor - Google Patents
Fiber bragg grating strain sensor Download PDFInfo
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- CN219572964U CN219572964U CN202120058244.0U CN202120058244U CN219572964U CN 219572964 U CN219572964 U CN 219572964U CN 202120058244 U CN202120058244 U CN 202120058244U CN 219572964 U CN219572964 U CN 219572964U
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Abstract
The utility model discloses a fiber bragg grating strain sensor, which relates to the field of sensors and comprises a mounting frame, a diaphragm, a transmission rod, an equal-strength beam and a compensation piece for compensating the temperature influence of the sensor, wherein the compensation piece comprises a compensation frame and an elastic piece; the compensation piece is arranged on the equal-strength beam, and the temperature is self-compensated by the compensation piece through transmitting test force on the equal-strength beam, so that the condition of central wavelength offset of each part caused by external environment temperature change is counteracted, and the cross sensitivity problem of temperature and pressure is effectively improved.
Description
Technical Field
The utility model relates to the field of sensors, in particular to a fiber bragg grating strain sensor.
Background
The strain sensor is a sensor based on measuring strain generated by the stressed deformation of an object and mainly comprises an electric sensor and an optical fiber sensor. The electrical sensor demodulates the relationship between pressure and the electrical signal by converting the pressure signal into a voltage or resistance signal; the fiber Bragg grating (FiberBraggGrating, FBG) sensor has the advantages of small volume, high precision, strong electromagnetic interference resistance, capability of long-distance signal transmission and the like, can perform high-precision real-time measurement and analysis on various parameters, and can replace an electrical sensor to become one of the most mature and reliable passive devices in the field of optical communication.
The basic principle of the FBG sensor is that a specific position of an optical fiber is made into a grating area with a refractive index periodically distributed, the optical wave of bragg reflected light is reflected in the area, and the reflected central wavelength signal is equal to the product of the grating period and the effective refractive index of the fiber core.
When the FBG sensor detects non-temperature parameters, the accuracy and reliability of the detection result can be affected by the change of the external environment temperature. In order to solve the cross sensitivity of FBG strain and temperature, researchers have proposed a number of temperature compensation methods, which are generally divided into a double-gate method and a single-gate method, but the double-gate method has the following problems: in the process of writing the fiber grating into the chip, various factors cross to influence the grating performance. In the actual detection process, the dynamic temperature causes temperature field change, the grating sensing temperature is different, and the result has the problems of constant amplitude compensation and phase lag; single gate method: the material packaging theory of different thermal expansion coefficients is simple, the processing and the manufacturing are easy, but the long-term stability of the whole structure is insufficient, the special structure packaging is designed based on the inherent property of the mechanical structure, the processing technology is immature, the long-term stability is insufficient, and the special material packaging and the software packaging are high in cost.
Disclosure of Invention
The utility model aims to solve the problems and designs the fiber bragg grating strain sensor.
The utility model realizes the above purpose through the following technical scheme:
the fiber bragg grating strain sensor comprises a mounting frame, a diaphragm, a transfer rod, an equal-strength beam and a compensation piece for compensating the temperature influence of the sensor, wherein the first end of the transfer rod is fixedly connected with the first side of the diaphragm, the first end of the equal-strength beam is fixedly connected with the mounting frame, the two ends of the diaphragm are fixedly connected with the mounting frame, the second end of the transfer rod is in extrusion contact with the equal-strength beam, the test force is applied to the second side of the diaphragm, and the compensation piece is arranged on the equal-strength beam.
The utility model has the beneficial effects that: the compensation piece is arranged on the equal-strength beam, and the temperature is self-compensated by the compensation piece through transmitting test force on the equal-strength beam, so that the condition of central wavelength offset of each part caused by external environment temperature change is counteracted, and the cross sensitivity problem of temperature and pressure is effectively improved.
Drawings
FIG. 1 is a front view block diagram of a fiber grating strain sensor of the present utility model;
FIG. 2 is a top view block diagram of a compensator in a fiber grating strain sensor of the present utility model;
fig. 3 is a diagram of simulation results of different side lengths l=5mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
fig. 4 is a diagram of simulation results of different side lengths l=6mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
fig. 5 is a diagram of simulation results of different side lengths l=7mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
fig. 6 is a diagram of simulation results of different side lengths l=8mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
FIG. 7 is a graph of the diamond side length of the compensation frame in the fiber grating strain sensor of the present utility model versus the sensitivity of the sensor;
fig. 8 is a diagram of simulation results of different thicknesses t=0.4 mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
fig. 9 is a diagram of simulation results of different thicknesses t=0.6 mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
fig. 10 is a diagram of simulation results of different thicknesses t=0.8 mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
fig. 11 is a diagram of simulation results of different thicknesses t=1mm of a compensation frame in the fiber bragg grating strain sensor of the present utility model;
FIG. 12 is a graph of diamond thickness t of a compensation frame in a fiber grating strain sensor of the present utility model versus sensor sensitivity;
wherein corresponding reference numerals are as follows:
1-compensation piece, 2-diaphragm, 3-transfer rod, 4-equal strength beam, 5-compensation frame, 6-elastic piece, 7-mounting bracket, 8-solder joint.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present utility model more clear, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. It will be apparent that the described embodiments are some, but not all, embodiments of the utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present utility model, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, or the directions or positional relationships conventionally put in place when the inventive product is used, or the directions or positional relationships conventionally understood by those skilled in the art are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific direction, be configured and operated in a specific direction, and therefore should not be construed as limiting the present utility model.
Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
In the description of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, terms such as "disposed," "connected," and the like are to be construed broadly, and for example, "connected" may be either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.
The following describes specific embodiments of the present utility model in detail with reference to the drawings.
As shown in fig. 1, the fiber bragg grating strain sensor comprises a mounting frame 7, a diaphragm 2, a transfer rod 3, an equal-strength beam 4 and a compensation piece 1 for compensating the temperature influence of the sensor, wherein a first end of the transfer rod 3 is fixedly connected with a first side of the diaphragm 2, a first end of the equal-strength beam 4 is fixedly connected with the mounting frame 7, two ends of the diaphragm 2 are fixedly connected with the mounting frame 7, a second end of the transfer rod 3 is in extrusion contact with the equal-strength beam 4, a testing force is applied to a second side of the diaphragm 2, and the compensation piece 1 is mounted on the equal-strength beam 4.
As shown in fig. 2, the compensation member 1 includes a compensation frame 5 and an elastic member 6, the compensation frame 5 has a diamond structure, two ends of a first diagonal line in the compensation frame 5 are welded and fixed with the equal-strength beam 4, and two ends of the elastic member 6 are respectively and fixedly connected with two ends of the first diagonal line of the compensation frame 5.
The length of the first diagonal of the compensation frame 5 is smaller than the length of the second diagonal of the compensation frame 5.
The side length of the compensation frame 5 is in the range of 6.75mm-7.25mm, and the shortest distance from the inner side to the outer side of the compensation frame 5 is in the range of 0.95mm-1.05mm.
The acute angle of the compensating frame 5 is in the range 55 deg. -65 deg..
The elastic member 6 is a spring.
The compensation frame 5 is made of aluminum.
Simulation experiment 1: the included angle of the fixed compensation frame 5 is 60 degrees, the value of the side length l is changed, the influence of the side length change on the sensor strain is explored by utilizing ANSYS, the length of a grating in engineering application is generally more than 10mm, therefore, the side length l of the compensation frame 5 is required to be controlled to be more than 5mm, the value of the diamond side length l is adjusted to be increased from 5mm to 8mm by taking 1mm as a step length in order to ensure the study precision and engineering practicability, simulation results are shown in fig. 3, 4, 5 and 6, fitting data are analyzed, the influence of the side length l change is influenced, and the deformation change of a sensor model is shown in fig. 7;
as can be seen from fig. 7, with the continuous increase of the diamond side length l of the compensation frame 5, the sensitivity of the sensor shows a positive increase trend, and further analysis shows that the diamond side length l has a larger influence on the sensitivity of the sensor, and since the size of the sensor mainly depends on the diamond side length l, and with the continuous increase of the sensitivity of the sensor, the measuring range of the sensor can be significantly reduced under the condition that other parameters are unchanged, so that the compensation frame 5 of the sensor has an optimal side length of 7 mm.
Simulation experiment 2: the diamond thickness t of the compensation frame 5 also affects the sensitivity of the sensor, the sensitivity is reduced when the diamond thickness t is too large, the measuring range is reduced when the diamond thickness t is too small, in order to balance the bilateral effect, the value of the diamond thickness t is adjusted to be 1mm from 0.4mm by taking 0.2mm as a step length under the condition that the length l of the diamond is 7mm and the included angle is 60 DEG unchanged, simulation results are shown in fig. 8, 9, 10 and 11, fitting data are analyzed, the sensitivity change of a sensor model is shown in fig. 12 under the influence of the change of the thickness t;
as can be seen from fig. 12, as the diamond thickness t of the compensation frame 5 increases, the sensitivity of the sensor presents a negative index, which is consistent with the theory related to the prior art, and further analysis shows that the strain sensitivity of the sensor gradually flattens, and in summary, to meet the bilateral requirements of the strain sensitivity and the processing technology level in engineering application, the thickness of the compensation frame 5 of the sensor is 1mm.
Simulation experiment 3, aiming at the actual engineering environment, carrying out thermodynamic analysis on the sensor provided by the utility model, adopting a thick plate to replace a measured object, combining a packaging principle, combining a compensation frame 5 with the thick plate, assembling the whole in three-dimensional composition software, introducing the combination into a finite element steady-state thermal analysis module, and adding parameters such as the heat conductivity coefficient, the thermal expansion coefficient, the Poisson ratio, the elastic modulus and the like of common materials at a material setting position, wherein the numerical values of the common materials are shown in the following table 1:
table 1 parameters relating to the materials
Wherein the substrate thick plate is made of plastic, the compensation frame 5 is made of aluminum, parameter setting is respectively carried out on each part, grid division is carried out after the parameter setting is finished, the initial temperature is set to be 22 ℃, and the final temperature is set to be 35 ℃, and solution is carried out; because the materials selected for the thick plate and the compensation frame 5 are different, the difference of thermal expansion coefficients can cause the structure to generate displacement difference, so that the diamond structure is deformed to different degrees. In the thermal stress profile, stress is concentrated on the main body portion of the compensation frame 5 and both ends of the fixed cylinder, and it is known that the sensor is structurally stable.
Aiming at the defects of the existing temperature compensation method, a novel diamond-structured temperature self-compensation theoretical model is provided based on the fiber bragg grating sensing principle and the diamond-structured deformation principle, so that the cross sensitivity problem of temperature and pressure is effectively improved; analyzing a temperature self-compensation theoretical model by combining a structure sensing mechanism of the diamond-shaped compensation frame 5 to obtain a matching relation between diamond-shaped structural materials and dimensional parameters and measured structural materials under a temperature self-compensation condition, selecting aluminum as the structural material, and verifying the temperature self-compensation property of the diamond-shaped structure in an ANSYS thermodynamic module;
the influence of the side length, the thickness and other self parameters of the diamond structure on the sensor characteristics is researched by the system, and the optimal diamond structure parameters are determined through simulation: the side length is 7mm, the thickness is 1mm, a sensing model is constructed and analyzed, and simulation verification proves that in order to realize temperature self-compensation, the outside environment temperature changes to cause the conclusion that the central wavelength offset of each part is mutually offset, so that the temperature self-compensation is effectively improved.
The diamond-shaped compensation frame 5 carries out experimental analysis, and compared with the traditional FBG strain sensor, the temperature sensitivity coefficient is greatly reduced and can be as low as 2.16 pm/DEG C; the diamond-shaped compensation frame 5 is subjected to stress and heated analysis, and the result shows that the stress deformation in the x direction and the stress deformation in the y direction are equal and can be eliminated, so that the diamond-shaped structural material under the temperature self-compensation condition and the relation between the structural parameter and the structural material to be measured are obtained, the relation with the sensitivity of the sensor is deduced, and the high-stability sensor is prepared.
The technical scheme of the utility model is not limited to the specific embodiment, and all technical modifications made according to the technical scheme of the utility model fall within the protection scope of the utility model.
Claims (7)
1. The fiber bragg grating strain sensor is characterized in that: including mounting bracket, diaphragm, transfer pole, equal strength roof beam and the compensator that is used for compensating sensor temperature to influence, the first end of transfer pole and the first side fixed connection of diaphragm, the first end and the mounting bracket fixed connection of equal strength roof beam, the both ends of diaphragm all with mounting bracket fixed connection, the second end and the equal strength roof beam extrusion contact of transfer pole, test force is applyed in the second side of diaphragm, the compensator is installed on equal strength roof beam.
2. The fiber grating strain sensor of claim 1, wherein: the compensation piece includes compensation frame and elastic component, and the compensation frame is diamond structure, and the both ends of the first diagonal in the compensation frame all with equal strength roof beam fixed connection, the both ends of elastic component respectively with the both ends fixed connection of the first diagonal of compensation frame.
3. The fiber grating strain sensor of claim 2, wherein: the length of the first diagonal of the compensation frame is smaller than the length of the second diagonal of the compensation frame.
4. A fiber grating strain sensor according to claim 2 or 3, wherein: the side length of the compensation frame ranges from 6.75mm to 7.25mm, and the shortest distance from the inner side to the outer side of the compensation frame ranges from 0.95mm to 1.05mm.
5. A fiber grating strain sensor according to claim 2 or 3, wherein: the acute angle of the compensation frame is 55-65 degrees.
6. A fiber grating strain sensor according to claim 2 or 3, wherein: the elastic piece is a spring.
7. A fiber grating strain sensor according to claim 2 or 3, wherein: the compensation frame is made of aluminum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120058244.0U CN219572964U (en) | 2021-01-11 | 2021-01-11 | Fiber bragg grating strain sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120058244.0U CN219572964U (en) | 2021-01-11 | 2021-01-11 | Fiber bragg grating strain sensor |
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| Publication Number | Publication Date |
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| CN219572964U true CN219572964U (en) | 2023-08-22 |
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| CN202120058244.0U Active CN219572964U (en) | 2021-01-11 | 2021-01-11 | Fiber bragg grating strain sensor |
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- 2021-01-11 CN CN202120058244.0U patent/CN219572964U/en active Active
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