CN110940292A - Fiber bragg grating buckling monitoring sensor and preparation method thereof - Google Patents
Fiber bragg grating buckling monitoring sensor and preparation method thereof Download PDFInfo
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- CN110940292A CN110940292A CN201911405808.7A CN201911405808A CN110940292A CN 110940292 A CN110940292 A CN 110940292A CN 201911405808 A CN201911405808 A CN 201911405808A CN 110940292 A CN110940292 A CN 110940292A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object
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Abstract
The invention discloses a fiber bragg grating buckling monitoring sensor and a preparation method thereof. The two fiber bragg grating sensitive elements are implanted in parallel in the fiber resin forming process to be packaged into fiber resin intelligent ribs, the fiber resin intelligent ribs are clamped on the stainless steel anchor head, and the two fiber bragg grating sensitive units are led out of the stainless steel anchor head through transmission jumper wires. The two fiber bragg grating sensitive units are arranged in the fiber resin intelligent rib at a certain distance, and the buckling states of the components such as the axial stressed slender straight rod and the like are evaluated through the compressive strain monitored by the two fiber bragg grating sensitive units.
Description
Technical Field
The invention belongs to the field of structural safety monitoring, and particularly relates to a fiber bragg grating buckling monitoring sensor and a preparation method thereof.
Background
The fiber grating belongs to a passive device, has the characteristics of small volume, electromagnetic interference resistance, strong corrosion resistance, high strain or temperature sensing sensitivity and the like, and is widely applied to structure monitoring in the fields of civil engineering, ocean engineering, aerospace, energy chemical engineering and the like at present. The bare fiber grating belongs to a thin-diameter structure, is easy to bend, causes poor compression resistance and shear resistance, and is not suitable for being directly used as a sensor for deformation monitoring of an engineering structure. At present, there are many reports of packaging techniques for fiber gratings. The common fiber grating strain sensor is to stick the fiber grating on the metal beam and to add the stainless steel sleeve for protection, in order to improve the negative pressure capability, a certain pre-tension stress is applied when the fiber grating is stuck, and the strain range is-1500 to +1500 mu epsilon. An anti-buckling fiber grating strain sensor (patent application number CN107101592A) reported adopts FRP (fiber reinforced plastic) to package a fiber grating, a designed anti-buckling constraint component and an anchoring component can effectively control the gap of the sensor, the anti-bending effect of the sensor is achieved, the integral stability of the sensor under pressure can be ensured, and the strain range can reach-3000 to +3000 mu epsilon.
When the pressure is too high, a member such as an axially compressed elongated straight rod may be suddenly bent, lose the original balance state of the straight line form, lose the capacity of continuously bearing, and cause instability. The reported fiber grating sensor with compression performance only focuses on the self compression resistance, and is used for evaluating the bearing capacity of the slender straight rod through sensor compression strain monitoring data when the pressure of the slender straight rod is monitored in the axial direction. But has the following disadvantages: the bearing capacity of the slender straight rod is closely related to the mechanical property of the slender straight rod, the bearing capacity of the slender straight rod is reduced when the slender straight rod is damaged, the instability critical compressive strain of the slender straight rod is reduced due to damage of the straight rod, and if the stability of the slender straight rod member is still evaluated according to the designed bearing capacity and the monitored compressive strain information, the risk of failure evaluation exists.
Therefore, a sensor capable of directly identifying instability of the axial compression components such as the slender straight rod is needed, and the sensor has important practical significance for carrying out local damage assessment of the structure.
Disclosure of Invention
In order to solve the technical problems, the invention provides a fiber bragg grating buckling monitoring sensor capable of identifying the instability direction of an axial compression member such as a slender rod and a preparation method thereof.
In order to achieve the purpose, the technical scheme of the invention is as follows: a fiber bragg grating buckling monitoring sensor and a preparation method thereof comprise the following steps: the fiber grating sensor comprises two fiber grating sensitive elements 1, fiber resin 2, a stainless steel anchor head 3 and a transmission jumper 4, and is characterized in that the two fiber grating sensitive elements 1 are implanted and encapsulated in parallel in the pultrusion process of the fiber resin 2 to form a fiber resin intelligent rib, the stainless steel anchor head 3 is clamped at two ends of the fiber resin intelligent rib, and the stainless steel anchor head 3 is led out of the fiber grating sensitive elements 1 through the transmission jumper 4.
The fiber in the fiber resin 2 is glass fiber, basalt fiber or carbon fiber, and the diameter of the pultruded fiber intelligent rib is 5mm, and the length of the pultruded fiber intelligent rib is 100 mm.
In the two fiber bragg grating sensitive elements 1, the main strain fiber bragg grating sensitive element 1-1 is arranged at the central position of the fiber resin intelligent rib; the direction strain fiber grating sensitive element 1-2 is arranged at the edge of the fiber resin intelligent rib, and the main strain fiber grating sensitive element 1-1 and the direction strain fiber grating sensitive element 1-2 are parallel and have a distance of 1.5 mm.
The stainless steel anchor head 3 comprises two semi-cylindrical anchor heads 3-1 and bolts 3-2, wherein the semi-cylindrical anchor heads 3-1 comprise solid sections 3-1-1 with the length of 5mm and hollow sections 3-1-2 with the length of 15 mm. The two semi-cylindrical anchor heads 3-1 are fastened by bolts 3-2 to form a stainless steel anchor head 3. The assembled stainless steel anchor head 3 has an inner diameter of 5mm, an outer diameter of 6mm and a length of 20 mm. Two holes with the diameter of 1.2mm are drilled in the solid section 3-1-1, the centers of the two holes are 1.5mm apart, and one hole is positioned in the center of the assembled stainless steel anchor head 3.
The diameter of the transmission jumper wire 4 is 1.1mm, and the fiber bragg grating sensitive element 1 penetrates through the transmission jumper wire 4 and is led out from two round holes in the stainless steel anchor head 3.
Compared with the existing fiber grating strain sensor, the fiber grating buckling sensor disclosed by the invention has the advantages that the fiber grating buckling sensor is fixedly arranged on an axial compression member such as a slender straight rod, the compression stress of the axial compression member can be monitored through the main strain fiber grating sensing element 1-1 arranged at the central position of the fiber composite intelligent rib, and the instability or buckling of the compression member can be monitored through the direction strain fiber grating sensing element 1-2 arranged at the edge position of the fiber composite intelligent rib.
Drawings
FIG. 1 is a schematic structural diagram of a fiber grating buckling monitoring sensor according to the present invention;
FIG. 2 is a schematic cross-sectional view of a fiber resin intelligent rib according to the present invention;
fig. 3 is a schematic view showing the structure of the stainless steel anchor head and the semi-cylindrical anchor head.
Fig. 4 is a schematic diagram of the fiber bragg grating buckling monitoring sensor arranged on the slender straight rod.
In fig. 1: 1, a fiber grating sensitive element; 2a fiber resin; 3, a stainless steel anchor head; and 4, transmitting a jumper wire.
In fig. 2: 1-1 main strain fiber grating sensitive element; 1-2 direction strain fiber grating sensitive element.
In fig. 3: 3-1 half cylindrical anchor head; 3-2 bolt; 3-1-1 solid segment; 3-1-2 hollow section
Detailed Description
The following detailed description of the invention refers to the accompanying drawings.
FIG. 1 is a schematic structural diagram of a fiber grating buckling monitoring sensor according to the present invention. The specific implementation mode is that the fiber grating sensitive units 1 are implanted together to form fiber material intelligent ribs in the pultrusion process of the fiber resin 2. Stainless steel anchor heads 3 are clamped at two ends of the fiber resin intelligent ribs, and the fiber bragg grating sensitive element 1 is led out of the stainless steel anchor heads through a transmission jumper 4. The fiber in the fiber resin 2 can be glass fiber, basalt fiber or carbon fiber, the diameter of the fiber resin intelligent rib is 5mm, and the length of the fiber resin intelligent rib is 100 mm.
FIG. 2 is a schematic cross-sectional view of the fiber resin intelligent rib of the present invention. The fiber bragg grating sensitive unit 1 comprises a main strain fiber bragg grating sensitive element 1-1 and a direction strain fiber bragg grating sensitive element 1-2, wherein the main strain fiber bragg grating sensitive element 1-1 is arranged at the central position of the fiber resin intelligent rib to monitor the compressive stress of the axial compression member; the direction strain fiber grating sensing element 1-2 is arranged at the edge position of the fiber resin intelligent rib to monitor the instability or buckling of the pressed component. The distance between the main strain fiber grating sensitive element 1-1 and the direction strain fiber grating sensitive element 1-2 is 1.5 mm.
Fig. 3 is a schematic view of a stainless steel anchor head structure. The specific implementation mode is as follows: the stainless steel anchor head 3 is a pressure type anchor head formed by fastening two semi-cylindrical anchor heads 3-1 through bolts 3-2, and the assembled stainless steel anchor head 3 has the outer diameter of 6mm, the inner diameter of 5mm and the length of 20 mm. The semi-cylindrical anchor head 3-1 comprises a solid section 3-1-1 and a hollow section 3-1-2, wherein the solid section 3-1-1 is 5mm long, and the hollow section 3-1-2 is 15mm long. And two holes with the diameter of 1.2mm are drilled in the solid section 3-1-1, the centers of the two holes are 1.5mm apart, and one hole is positioned in the center of the assembled stainless steel anchor head. The two round holes are used for leading out the main strain fiber grating sensitive element 1-1 and the direction strain fiber grating sensitive unit 1-2 on the fiber resin intelligent bar from the stainless steel anchor head 3. The solid section 3-1-1 is used for ensuring that the fiber resin intelligent rib is restrained by the solid section 3-1-1 and does not slide with the stainless steel anchor head 3 in the process of pressing the sensor; the hollow section 3-1-2 is used for clamping the fiber resin intelligent rib. Four bolts 3-2 on the stainless steel anchor head 3 are used for fastening the anchor head and applying a certain positive pressure on the fiber resin intelligent bars.
Fig. 4 is a schematic diagram of the fiber bragg grating buckling monitoring sensor arranged on the slender straight rod. The specific implementation mode is as follows: the fiber bragg grating buckling monitoring sensor is arranged in the middle of the axial compressed slender straight rod through the anchoring piece, and the form of the anchoring piece is determined according to a monitored object. The magnitude of the compressive strain monitored by the main strain fiber grating sensitive unit 1-1 and the direction strain fiber grating sensitive unit 1-2 in the fiber grating buckling monitoring sensor is equal, which indicates that the axial stressed slender straight rod is not unstable or buckled. The compressive strain monitored by the main strain fiber grating sensing unit 1-1 is not equal to the compressive strain monitored by the direction strain fiber grating sensing unit 1-2, which indicates that the axially compressed slender straight rod is unstable, at the moment, the slender straight rod is bent and deformed, and the fiber grating buckling monitoring sensor is bent and bent. If the pressure strain monitored by the main strain fiber grating sensitive unit 1-1 is larger than the pressure strain monitored by the direction strain fiber grating sensitive unit 1-2, the fiber grating buckling monitoring sensor is inwards bent towards one side of the direction strain fiber grating sensitive unit 1-2; and otherwise, the fiber bragg grating buckling monitoring sensor is bent outwards towards one side of the strain fiber bragg grating sensitive unit 1-2 in the direction. According to the bending direction evaluation of the fiber bragg grating buckling monitoring sensor, the bending direction of the slender straight rod can be monitored and identified.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention.
Claims (5)
1. A fiber bragg grating buckling monitoring sensor and a preparation method thereof comprise a fiber bragg grating sensitive unit (1), fiber resin (2), a stainless steel anchor head (3) and a transmission jumper (4); the method is characterized in that:
the fiber resin intelligent ribs are formed by parallelly implanting and packaging the two fiber grating sensitive units (1) in the fiber resin (2) forming process, stainless steel anchor heads (3) are clamped at two ends of each fiber resin intelligent rib, and the stainless steel anchor heads (3) are led out of the fiber grating sensitive units (1) through transmission jumper wires (4).
2. The fiber bragg grating buckling monitoring sensor and the manufacturing method thereof according to claim 1, wherein the fiber in the fiber resin (2) is glass fiber, basalt fiber or carbon fiber, and the diameter of the molded fiber intelligent rib is 5mm, and the length of the molded fiber intelligent rib is 100 mm.
3. The fiber bragg grating buckling monitoring sensor and the manufacturing method thereof as claimed in claims 1 and 2, wherein the fiber bragg grating sensing element (1) comprises a main strain fiber bragg grating sensing element (1-1) and a direction strain fiber bragg grating sensing unit (1-2). The main strain fiber grating sensitive element (1-1) is arranged at the central position of the fiber resin intelligent rib, and the direction strain fiber grating sensitive element (1-2) and the main strain fiber grating sensitive element are arranged in parallel and have a distance of 1.5 mm.
4. The fiber bragg grating buckling monitoring sensor and the preparation method thereof as claimed in claims 1, 2 and 3, wherein: the stainless steel anchor head (3) comprises two semi-cylindrical anchor heads (3-1) and bolts (3-2), wherein the semi-cylindrical anchor heads (3-1) are divided into solid sections (3-1-1) with the length of 5mm and hollow sections (3-1-2) with the length of 15 mm. Two round holes with the diameter of 1.2mm are drilled in the solid section (3-1-1), and the center distance between the two round holes is 1.5 mm. Two ends of the fiber resin intelligent bar are fixed on the four semi-cylindrical anchor heads (3-1) through bolts (3-2).
5. The fiber grating buckling monitoring sensor and the preparation method thereof as claimed in claims 1, 2, 3 and 4, wherein: two fiber bragg grating sensitive elements (1) penetrate through a transmission jumper (4) with the diameter of 1.1mm and are led out from two round holes in a solid section (3-1-1) in a stainless steel anchor head (3).
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911405808.7A CN110940292A (en) | 2019-12-31 | 2019-12-31 | Fiber bragg grating buckling monitoring sensor and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911405808.7A CN110940292A (en) | 2019-12-31 | 2019-12-31 | Fiber bragg grating buckling monitoring sensor and preparation method thereof |
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| CN110940292A true CN110940292A (en) | 2020-03-31 |
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| CN201911405808.7A Pending CN110940292A (en) | 2019-12-31 | 2019-12-31 | Fiber bragg grating buckling monitoring sensor and preparation method thereof |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001055672A1 (en) * | 2000-01-28 | 2001-08-02 | Mitsubishi Cable Industries, Ltd. | Fiber optic cable and method of measuring distortion |
| CN1683903A (en) * | 2005-03-17 | 2005-10-19 | 上海交通大学 | Method for simultaneously measuring bending curvature and bending direction |
| CN201567531U (en) * | 2009-09-30 | 2010-09-01 | 法尔胜集团公司 | Smart cable device for bridges with optical fiber grating sensor inside |
| CN203518948U (en) * | 2013-10-25 | 2014-04-02 | 中国矿业大学 | Monitoring device for roof separation of mining fiber grating |
| CN104101306A (en) * | 2014-07-24 | 2014-10-15 | 河海大学 | Fiber bragg grating temperature compensation method and ultrathin miniature rebar strainometer |
| CN107101592A (en) * | 2017-06-21 | 2017-08-29 | 智性科技南通有限公司 | A kind of anti-buckling fiber Bragg grating strain sensor and preparation method thereof |
| CN108180866A (en) * | 2017-12-31 | 2018-06-19 | 西北大学 | Fiber grating vector curved-ray tracing device |
-
2019
- 2019-12-31 CN CN201911405808.7A patent/CN110940292A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001055672A1 (en) * | 2000-01-28 | 2001-08-02 | Mitsubishi Cable Industries, Ltd. | Fiber optic cable and method of measuring distortion |
| CN1683903A (en) * | 2005-03-17 | 2005-10-19 | 上海交通大学 | Method for simultaneously measuring bending curvature and bending direction |
| CN201567531U (en) * | 2009-09-30 | 2010-09-01 | 法尔胜集团公司 | Smart cable device for bridges with optical fiber grating sensor inside |
| CN203518948U (en) * | 2013-10-25 | 2014-04-02 | 中国矿业大学 | Monitoring device for roof separation of mining fiber grating |
| CN104101306A (en) * | 2014-07-24 | 2014-10-15 | 河海大学 | Fiber bragg grating temperature compensation method and ultrathin miniature rebar strainometer |
| CN107101592A (en) * | 2017-06-21 | 2017-08-29 | 智性科技南通有限公司 | A kind of anti-buckling fiber Bragg grating strain sensor and preparation method thereof |
| CN108180866A (en) * | 2017-12-31 | 2018-06-19 | 西北大学 | Fiber grating vector curved-ray tracing device |
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Application publication date: 20200331 |