Fiber Bragg Grating Sensor, Carbon Fiber Composite Conductor and Manufacturing Method

Abstract

The present invention relates to the technical field of carbon fiber composite conductors, and particularly relates to an optical fiber grating sensor, a carbon fiber composite conductor and a manufacturing method thereof. The optical fiber grating sensor includes: a carbon fiber tube; an optical fiber on which a detection grating is inscribed, and the optical fiber is inserted into the carbon fiber tube; a carbon fiber sheet layer filled between the carbon fiber tube and the optical fiber and cured integrally with the carbon fiber tube. The carbon fiber composite conductor includes: a carbon fiber core rod; the aforementioned optical fiber grating sensor; and an aluminum stranded layer. The optical fiber grating sensor of the present invention uses a carbon fiber tube and a carbon fiber sheet layer to encapsulate the optical fiber, which can improve the detection sensitivity. The carbon fiber composite conductor of the present invention uses a carbon fiber tube and a carbon fiber sheet layer to encapsulate the sensor, which is made of the same material as the core rod of the carbon fiber composite conductor and has the same coefficient of thermal expansion, facilitating accurate measurement of the stress and strain of the core rod, and can avoid the thermal stress generated between different materials, further improving the detection sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber composite conductors, and particularly relates to a fiber Bragg grating sensor, a carbon fiber composite conductor and a manufacturing method thereof. Background Art

[0002] A carbon fiber composite conductor is an energy-saving and capacity-increasing conductor with a brand-new structure. Compared with conventional conductors, it has a series of advantages such as light weight, good heat resistance, high conductivity, low line loss, large current-carrying capacity, good corrosion resistance, and not easy to ice. The carbon fiber composite conductor includes a carbon fiber core rod and an aluminum stranded layer on its outer side. At present, most carbon fiber core rods are single-core, and their bending, folding and splitting resistance capabilities are weak. Once a very small part is damaged, the whole rod is extremely easy to break, and because it is inside the aluminum stranded layer, it is not easy to be discovered.

[0003] Therefore, since 2014, some scientific research institutions and enterprises have begun to embed fiber Bragg grating sensors in carbon fiber core rods to judge the damage condition of the carbon fiber core rods by detecting temperature and stress. In order to ensure the detection of stress, the existing fiber Bragg grating sensors generally directly bury the optical fiber into the carbon fiber core rod. The optical fiber is wrapped by resin and glass fiber, and prestress cannot be formed, and the detection sensitivity of the optical fiber is relatively low. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of insufficient sensitivity of the fiber Bragg grating sensor in the carbon fiber composite conductor in the prior art, so as to provide a fiber Bragg grating sensor, a carbon fiber composite conductor and a manufacturing method thereof.

[0005] The fiber Bragg grating sensor provided by the present invention includes:

[0006] A carbon fiber tube;

[0007] An optical fiber with a detection grating written thereon, and the optical fiber is inserted into the carbon fiber tube;

[0008] A carbon fiber sheet layer, filled between the carbon fiber tube and the optical fiber, and cured into one body with the carbon fiber tube;

[0009] The optical fiber is wrapped by the carbon fiber sheet layer to form prestress.

[0010] Optionally, the detection grating includes a Bragg temperature detection grating and a Bragg stress detection grating.

[0011] The manufacturing method of the fiber Bragg grating sensor provided by the present invention includes the following steps:

[0012] S1. Cut the carbon fiber sheet into a strip structure, lay it flat on the first template to form a first layer of carbon fiber layer, and make the length direction of the strip structure consistent with the optical fiber;

[0013] S2. Apply a layer of epoxy resin glue on the surface of the first-layer carbon fiber layer;

[0014] S3. Lay strip-shaped carbon fiber sheets on the surface of the epoxy resin glue to form the second-layer carbon fiber layer;

[0015] S4. Apply a layer of epoxy resin glue on the surface of the second-layer carbon fiber layer, and alternately form multiple layers of carbon fiber layers in this way. In this step, insert the optical fiber engraved with the detection grating into the adjacent two layers of carbon fiber layers, and keep the optical fiber in a prestressed state;

[0016] S5. Press the multiple layers of carbon fiber layers with the second template to squeeze out the excess epoxy resin glue;

[0017] S6. Roll the structure formed in step S5 into a columnar structure with the optical fiber as the axis;

[0018] S7. Insert the columnar structure into the carbon fiber tube to complete the processing.

[0019] A carbon fiber composite conductor provided by the present invention includes:

[0020] A carbon fiber core rod;

[0021] The aforementioned fiber optic grating sensor, which is parallel to the carbon fiber core rod;

[0022] An aluminum stranded layer, which winds and fixes the carbon fiber rod and the fiber optic grating sensor.

[0023] Preferably, the carbon fiber core rod and the carbon fiber tube of the fiber optic grating sensor are cured into an integral structure.

[0024] Preferably, there are multiple layers of the aluminum stranded layer.

[0025] The manufacturing method of the carbon fiber composite conductor provided by the present invention includes the following steps:

[0026] S1. Pre-fabricate the aforementioned fiber optic grating sensor;

[0027] S2. Place the fiber optic grating sensor, carbon fiber filaments, and glass fibers in parallel, and infiltrate them with epoxy resin, and heat and cure them into a carbon fiber composite structure core rod;

[0028] S3. Strangle aluminum wires on the outside of the carbon fiber composite structure core rod to form an aluminum stranded layer.

[0029] The technical solution of the present invention has the following advantages:

[0030] 1. The fiber Bragg grating sensor provided by the present invention includes an optical fiber engraved with a detection grating, and the optical fiber can detect the temperature and strain of the surrounding structure. The optical fiber is encapsulated with a carbon fiber sheet layer. Since the expansion coefficient of the carbon fiber sheet layer is one order of magnitude larger than that of the optical fiber, the sensitivity of the sensor detection will be improved; the carbon fiber sheet layer is encapsulated with a carbon fiber tube, which can ensure the prestress of the optical fiber, thereby ensuring the sensitivity; the carbon fiber tube has good corrosion resistance and far better abrasion resistance than other metal materials, and can better protect the optical fiber and be durable in the national standard requirements of the wire; the carbon fiber tube is a non-magnetic material, which can avoid electromagnetic interference and power loss when transmitting high-voltage alternating current power wires; the carbon fiber tube and the carbon fiber sheet layer are of the same material, and can be impregnated and cured with epoxy resin to form an integral body that can both protect the optical fiber and enhance sensitivity. The sensitivity can reach 30 pm / degree, and the measurement accuracy of 1 degree Celsius can be achieved, fully meeting the requirements of temperature and stress measurement of the wire. In addition, the carbon fiber tube and the carbon fiber core rod of the carbon fiber composite wire are of the same material and have the same coefficient of thermal expansion, which is convenient for accurately measuring the stress and strain of the core rod, can avoid thermal stress generated between different materials, and improve the sensitivity. Therefore, the structure of this sensor is more suitable for application in carbon fiber composite wires.

[0031] 2. The fiber Bragg grating sensor provided by the present invention, the detection grating is a Bragg temperature detection grating and a Bragg stress detection grating. The Bragg grating can simultaneously detect the changes of external temperature and stress, reducing the demodulation difficulty of temperature and stress signals.

[0032] 3. The manufacturing method of the fiber Bragg grating sensor provided by the present invention uses a carbon fiber material as the base material, and uses epoxy resin glue as the connector. The carbon fiber sheets are made into a carbon fiber multi-layer structure by stacking them layer by layer, and the optical fiber engraved with the Bragg grating is encapsulated therein. This operation process is simple, low-cost, convenient for cooperating with the production of large-scale long-distance wires, has good measurement linearity, and is convenient for filling into a carbon fiber tube for encapsulation and curing into an integral body.

[0033] 4. The carbon fiber composite wire provided by the present invention has any one of the advantages of the fiber Bragg grating sensor because it has the aforementioned fiber Bragg grating sensor.

[0034] 5. The carbon fiber composite wire provided by the present invention makes the carbon fiber core rod and the fiber Bragg grating sensor into a carbon fiber composite structure core rod through coaxial infiltration of epoxy resin and heating and curing, making it have better integrity and improving the sensitivity.

[0035] 6. The carbon fiber composite wire provided by the present invention, the aluminum stranded layer can be multi-layered, and can be appropriately increased or decreased according to specific usage situations, and can adapt to different usage scenarios.

[0036] 7. The manufacturing method of the carbon fiber composite wire provided by the present invention includes the manufacturing process of the aforementioned fiber Bragg grating sensor, so it has any of the advantages of this manufacturing process. Moreover, the fiber Bragg grating sensor is integrally cured and formed with the carbon fiber core rod, which is simple to process and can improve the detection sensitivity of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a cross-sectional schematic diagram of the fiber Bragg grating sensor in the embodiment of the present invention;

[0039] Figure 2 It is a cross-sectional schematic diagram of the carbon fiber composite wire in the embodiment of the present invention.

[0040] Description of the reference numerals:

[0041] 1. Optical fiber; 2. Carbon fiber sheet layer; 3. Carbon fiber tube; 4. Fiber Bragg grating sensor; 5. Carbon fiber core rod; 6. Aluminum stranded layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] Embodiment 1

[0043] Referring to Figure 1 , this embodiment provides a fiber Bragg grating sensor, including:

[0044] Carbon fiber tube 3;

[0045] Optical fiber 1, on which a detection grating is inscribed, and the optical fiber 1 is inserted into the carbon fiber tube 3;

[0046] Carbon fiber sheet layer 2, filled between the carbon fiber tube 3 and the optical fiber 1, and cured into one body with the carbon fiber tube 3;

[0047] The optical fiber 1 is wrapped by the carbon fiber sheet layer 2 to form prestress.

[0048] The above fiber Bragg grating sensor includes an optical fiber 1 engraved with a detection grating, and the optical fiber 1 can detect the temperature and strain of the surrounding structure. The optical fiber 1 is encapsulated by a carbon fiber sheet layer 2. Since the thermal expansion coefficient of the carbon fiber sheet layer 2 is one order of magnitude larger than that of the optical fiber 1, the sensitivity of the sensor detection will be improved; the carbon fiber sheet layer 2 is encapsulated by a carbon fiber tube 3, which can ensure the prestress of the optical fiber 1, thereby ensuring the sensitivity; the carbon fiber tube 3 has good corrosion resistance and far better abrasion resistance than other metal materials, and can better protect the optical fiber 1 and be durable in the national standard requirements of the wire; the carbon fiber tube 3 is a non-magnetic material, which can avoid electromagnetic interference and power loss when transmitting high-voltage alternating current power wires; the carbon fiber tube 3 and the carbon fiber sheet layer 2 are of the same material, and can be impregnated and cured with epoxy resin to form an integral body that can both protect the optical fiber 1 and increase sensitivity. The sensitivity can reach 30 pm / degree, and the measurement accuracy of 1 degree Celsius can be achieved, fully meeting the requirements of wire temperature measurement and stress measurement. In addition, the carbon fiber tube 3 and the carbon fiber core rod of the carbon fiber composite wire are of the same material and have the same thermal expansion coefficient, which is convenient for accurately measuring the stress and strain of the core rod, can avoid the thermal stress generated between different materials, and improve the sensitivity. Therefore, the structure of this sensor is more suitable for application in carbon fiber composite wires.

[0049] Preferably, the detection grating is a Bragg temperature detection grating and a Bragg stress detection grating. The Bragg grating can simultaneously detect the changes in the external temperature and stress, reducing the demodulation difficulty of the temperature and stress signals.

[0050] As an alternative implementation of the detection grating, the detection grating may also only include a temperature detection grating or a stress detection grating.

[0051] Embodiment 2

[0052] This embodiment provides a manufacturing method of a fiber Bragg grating sensor 4, including the following steps:

[0053] S1. Cut the carbon fiber sheet into a strip structure, lay it flat on the first template to form the first layer of carbon fiber layer, and make the length direction of the strip structure consistent with the optical fiber;

[0054] S2. Apply a layer of epoxy resin glue on the surface of the first layer of carbon fiber layer;

[0055] S3. Lay a strip-shaped carbon fiber sheet on the surface of the epoxy resin glue to form the second layer of carbon fiber layer;

[0056] S4. Apply a layer of epoxy resin glue on the surface of the second layer of carbon fiber layer, and alternately form multiple layers of carbon fiber layers in this way. In this step, the optical fiber 1 engraved with the detection grating is inserted into adjacent two layers of carbon fiber layers, and the optical fiber is kept in a prestressed state;

[0057] S5. Press the multiple layers of carbon fiber layers with the second template to squeeze out the excess epoxy resin glue;

[0058] S6. Roll the structure formed in step S5 into a columnar structure with the optical fiber 1 as the axis;

[0059] S7. Insert the columnar structure into the carbon fiber tube 3 to complete the processing.

[0060] The manufacturing method of the fiber Bragg grating sensor 4 provided in this embodiment uses a carbon fiber material as the base material, uses an epoxy resin adhesive as the connector, makes a carbon fiber multi-layer structure by stacking carbon fiber sheets layer by layer, and encapsulates the optical fiber 1 engraved with a Bragg grating therein. This operation process is simple, low-cost, convenient for cooperating with the production of large-scale long-distance wires, has good measurement linearity, and is convenient for filling into the carbon fiber tube 3 for encapsulation and curing into a whole.

[0061] Specifically, the template one and the template two are flat plates. By using the template one and the template two in cooperation, the excess epoxy resin adhesive in the interlayer can be extruded, which can improve the integrity of the multi-layer carbon fiber layer.

[0062] Specifically, when using the template two to press the multi-layer carbon fiber layer, it needs to be maintained for 1-2 hours to completely extrude the excess epoxy resin adhesive.

[0063] Specifically, the carbon fiber tube 3 used in step S7 is made of T700-1200K carbon fiber filaments by a 3D rotary braiding method into a longitudinally high elastic modulus hollow carbon fiber tube 3.

[0064] Embodiment 3

[0065] Refer to Figure 2 , this embodiment provides a carbon fiber composite wire, including:

[0066] A carbon fiber core rod 5;

[0067] The aforementioned fiber Bragg grating sensor 4, which is parallel to the carbon fiber core rod 5;

[0068] An aluminum stranded layer 6, and the aluminum stranded layer 6 winds and fixes the carbon fiber core rod 5 and the fiber Bragg grating sensor 4.

[0069] In this embodiment, through the setting of the fiber Bragg grating sensor 4, it is possible to quickly and effectively detect the damaged part when the wire is damaged. And by using the aforementioned fiber Bragg grating sensor 4, the carbon fiber tube 3 and the carbon fiber core rod 5 are made of the same material and have the same coefficient of thermal expansion, which is convenient for accurately measuring the stress and strain of the carbon fiber core rod 5, can avoid the thermal stress generated between different materials, and improve the sensitivity.

[0070] In addition, when the fiber Bragg grating sensor 4 is damaged, since both the carbon fiber and the optical fiber 1 are high-temperature resistant materials, it is only necessary to heat to the glass transition temperature of the epoxy resin (usually above 200 degrees), and the fiber Bragg grating sensor 4 can be withdrawn and replaced while maintaining the temperature. There is no need to replace the carbon fiber composite wire, and its composition will not be damaged. This avoids the unnecessary waste caused by the damage of the optical fiber 1 due to external forces such as lightning strikes, human abrasion, and falling objects from high altitudes that often occur during operation, and the inability to continue using the original relatively expensive carbon fiber wire by only replacing the optical fiber 1.

[0071] Specifically, the carbon fiber core rod 5 and the fiber Bragg grating sensor 4 can be fixed only by winding with the aluminum stranded layer 6, or other fixing structures can be used for reinforcement.

[0072] As an improved implementation manner of the carbon fiber composite wire, the carbon fiber core rod 5 and the carbon fiber tube 3 of the fiber Bragg grating sensor 4 are cured into an integral structure. The carbon fiber core rod 5 and the fiber Bragg grating sensor 4 are infiltrated with epoxy resin coaxially and heated and cured to form a carbon fiber composite structure core rod, so as to have better integrity and improve sensitivity.

[0073] Preferably, there are multiple layers of the aluminum stranded layer 6. The number of the aluminum stranded layer 6 can be appropriately increased or decreased according to the specific usage situation to adapt to different usage scenarios.

[0074] Specifically, the number of the fiber Bragg grating sensors 4 in the carbon fiber composite wire is not limited, and can be 1, 2, or multiple. For example Figure 2 as shown in [reference] is 4.

[0075] Specifically, the position of the fiber Bragg grating sensor 4 in the carbon fiber core rod 5 is not limited. It can be at the center of the carbon fiber core rod 5, or at an eccentric position inside the carbon fiber core rod 5, or at the edge position of the carbon fiber core rod 5.

[0076] During detection, a spectrometer is used to analyze the central wavelength drift of the light source passing through the grating, and through the differential decoupling modulation of the Bragg temperature detection grating and the Bragg stress detection grating, the temperature and stress changes of the carbon fiber wire core rod 5 are obtained respectively. If it is found that the continuous stress of a certain part of the wire based on the catenary equation of the initial value has a mutation, it is judged that the core rod is damaged. If it is found that the temperature suddenly rises, it may be a fault such as lightning strike or overload.

[0077] Example 4

[0078] This embodiment provides a manufacturing method of a carbon fiber composite wire, including the following steps:

[0079] S1. Pre-fabricate the aforementioned fiber Bragg grating sensor 4;

[0080] S2. Place the fiber Bragg grating sensor 4 parallel to the carbon fiber filaments and glass fibers, soak them in epoxy resin, and heat and cure them into a carbon fiber composite structure core rod;

[0081] S3. Stranded aluminum wire on the outside of the carbon fiber composite structure core rod to form an aluminum stranded layer 6.

[0082] In the above manufacturing method, the fiber Bragg grating sensor 4 and the carbon fiber core rod 5 are integrally cured and formed, which is simple to process and can improve the sensitivity of sensor detection.

[0083] Obviously, the above embodiments are only examples given for clear illustration, and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. An optical fiber grating sensor, characterized in that, Comprising: A carbon fiber tube (3); An optical fiber (1) with a detection grating inscribed thereon, and the optical fiber (1) is inserted into the carbon fiber tube (3); A carbon fiber sheet layer (2) filled between the carbon fiber tube (3) and the optical fiber (1) and cured integrally with the carbon fiber tube (3); The optical fiber (1) is wrapped by the carbon fiber sheet layer (2) to form a prestress; The manufacturing method of the optical fiber grating sensor comprises the following steps: S1. Cut the carbon fiber sheet into a strip structure, lay it flat on the first template to form a first layer of carbon fiber layer, and make the length direction of the strip structure consistent with that of the optical fiber (1); S2. Apply a layer of epoxy resin glue on the surface of the first layer of carbon fiber layer; S3. Lay a strip-shaped carbon fiber sheet on the surface of the epoxy resin glue to form a second layer of carbon fiber layer; S4. Apply a layer of epoxy resin glue on the surface of the second layer of carbon fiber layer, and alternately form multiple layers of carbon fiber layers in this way. In this step, insert the optical fiber (1) with the detection grating inscribed thereon between adjacent two layers of carbon fiber layers and keep the optical fiber (1) in a prestressed state; S5. Press the multiple layers of carbon fiber layers with the second template to squeeze out the excess epoxy resin glue; S6. Roll up the structure formed in step S5 into a columnar structure with the optical fiber (1) as the axis; S7. Insert the columnar structure into the carbon fiber tube (3) to complete the processing.

2. The fiber Bragg grating sensor according to claim 1, wherein The detection grating includes a Bragg temperature detection grating and a Bragg stress detection grating.

3. A carbon fiber composite conductor, characterized in that, Comprising: A carbon fiber core rod (5); The optical fiber grating sensor as claimed in claim 1 or 2, which is parallel to the carbon fiber core rod (5); An aluminum stranded layer (6) which winds and fixes the carbon fiber rod and the optical fiber grating sensor.

4. The carbon fiber composite conductor according to claim 3, wherein, The carbon fiber core rod (5) and the carbon fiber tube (3) of the optical fiber grating sensor are cured into an integral structure.

5. The carbon fiber composite conductor according to claim 3 or 4, characterized in that, The aluminum stranded layer (6) is provided with multiple layers.

6. A manufacturing method of a carbon fiber composite wire, characterized in that, Comprising the following steps: S1. Pre-fabricate the optical fiber grating sensor as claimed in claim 1 or 2; S2. Place the optical fiber grating sensor, carbon fiber filaments and glass fibers in parallel, soak them with epoxy resin, and heat and cure them into a carbon fiber composite structure core rod; S3. Strangle aluminum wires on the outer side of the carbon fiber composite structure core rod to form an aluminum stranded layer (6).

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