Method for integrating distributed optical fibers into tested structure

Abstract

The invention relates to the technical field of optical fiber sensing detection, and discloses a method for integrating distributed optical fibers on a detected structure, which comprises the following steps of: S1, uniformly coating a soldering tin layer on the surface of the detected structure; s2, arranging a high-temperature-resistant adhesive tape on the surface of the tested structure to form a welding groove; s3, the distributed optical fibers are placed in the welding groove, and the welding groove is filled with liquid scaling powder; and S4, hanging a soldering tin layer on the surface of the welding gun in advance, and welding the distributed optical fibers on the surface of the detected structure by the welding gun. The method has the following technical effects that by adopting the method, the integration stability and firmness of the distributed optical fiber can be improved, the situation that the distributed optical fiber cracks, folds or disengages on a tested structure is prevented, especially in extreme multi-field environments such as alternating load and large-amplitude temperature change, meanwhile, the time consumed in the integration process can be shortened, and the integration efficiency of the distributed optical fiber is improved. The integration efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensing detection, and in particular relates to a method for integrating distributed optical fiber into a measured structure. Background Art

[0002] As a sensor, distributed optical fiber is widely used in structural health monitoring (SHM) due to its advantages such as corrosion resistance, resistance to electromagnetic interference, small size, light weight, and easy burial inside the structure under test. Structural health monitoring (SHM) is usually achieved by integrating distributed optical fiber into the structure under test.

[0003] At present, the method of integrating distributed optical fiber into the structure under test is usually the bonding method, which is mainly through the use of adhesives such as epoxy resin or glue to bond and solidify on the surface of the structure under test. However, after a period of use, the distributed optical fiber on the surface of the structure under test is very likely to wrinkle, crack or debond when the distributed optical fiber is integrated on the structure under test by the bonding method, especially under extreme multi-field environments such as alternating loads and large temperature changes (400K to 4.2K). The physical properties of the adhesive and the structure under test show strong differences at room temperature, which easily causes the increase of the stiffness and brittleness of the adhesive itself. In particular, when the distributed optical fiber is bonded and solidified on the surface of the structure under test, the huge difference in thermal expansion coefficient between the adhesive and the structure under test generates a large amount of residual stress inside the adhesive, initiating many microcracks, wrinkles, etc., causing the adhesive adhesion to weaken, reducing the transmission efficiency of the measurement signal, and thus leading to measurement failure. In addition, the use of adhesives for distributed optical fiber integration requires a long curing time, especially for long superconducting wires or coils, and therefore cannot meet the actual industrial production applications. Summary of the invention

[0004] In order to address the deficiencies of the prior art, the present invention provides a method for integrating a distributed optical fiber into a structure to be measured. By pre-coating a layer of solder on the surface of the structure to be measured and a welding gun, and welding the distributed optical fiber into a welding groove on the surface of the structure to be measured, the integrated stability and firmness of the distributed optical fiber can be improved, and the distributed optical fiber can be prevented from cracking, wrinkling or detaching on the structure to be measured, especially in extreme multi-field environments such as alternating loads and large temperature changes. At the same time, it can also shorten the time consumed in the integration process, improve the integration efficiency, and be more conducive to actual industrial production applications.

[0005] The technical effects to be achieved by the present invention are achieved through the following technical aspects: The present invention provides a method for integrating a distributed optical fiber into a structure to be tested, comprising the following steps: S1. Uniformly apply a layer of solder on the surface of the structure to be tested; S2. Use high temperature resistant tape to lay out welding grooves on the surface of the structure to be tested; S3, placing the distributed optical fiber in the soldering tank, and filling the soldering tank with liquid flux; S4. A layer of solder is pre-applied on the surface of the welding gun, and the welding gun welds the distributed optical fiber to the surface of the structure to be measured.

[0006] As a further description of the technical solution of the present invention, in S1, the thickness of the solder layer is 0.8-1.5 μm.

[0007] As a further description of the technical solution of the present invention, in S3, the distributed optical fiber is placed in a central position in the welding groove.

[0008] As a further description of the technical solution of the present invention, the shape of the welding groove includes one or a combination of linear, rectangular, circular, arc or triangular.

[0009] As a further description of the technical solution of the present invention, the surface of the distributed optical fiber has a metal and / or metal compound protective layer.

[0010] As a further description of the technical solution of the present invention, the metal and / or metal compound protective layer includes one of copper and its compounds, gold and its compounds, titanium and its compounds, or nickel and its compounds.

[0011] As a further description of the technical solution of the present invention, the structure to be measured is a superconducting wire or a superconducting coil.

[0012] As a further description of the technical solution of the present invention, the following steps are specifically included: S1. Uniformly coat a solder layer on the surface of the superconducting wire; S2, using high temperature resistant tape to lay out welding grooves on the surface of superconducting wire; S3, fixing the distributed optical fiber in the welding groove of the superconducting wire, and spraying liquid soldering flux into the welding groove with a liquid soldering flux spray gun; S4. A layer of solder is pre-applied on the surface of the welding gun, and the welding gun welds the distributed optical fiber to the surface of the superconducting wire.

[0013] As a further description of the technical solution of the present invention, during the process of spraying the liquid flux and welding, the positions of the liquid flux spray gun and the welding gun are fixed, and the superconducting wire and the distributed optical fiber move synchronously.

[0014] As a further description of the technical solution of the present invention, after the liquid flux spray gun is started, the welding gun is started again when the superconducting wire and the distributed optical fiber that have been sprayed with liquid flux move to corresponding positions of the welding gun.

[0015] In summary, the present invention has at least the following benefits: The method for integrating distributed optical fiber into a measured structure provided by the present invention can improve the integration stability and firmness of the distributed optical fiber by arranging welding grooves on the surface of the measured structure and welding the distributed optical fiber into the welding grooves, effectively prevent the distributed optical fiber from cracking, wrinkling or detaching on the measured structure, especially under extreme multi-field environments such as alternating loads and large temperature changes. At the same time, it can also shorten the time consumed in the integration process, improve the integration efficiency, and be more conducive to actual industrial production applications; by pre-coating a layer of solder on the surface of the measured structure and the welding gun, the welding affinity between the distributed optical fiber and the measured structure can be improved, so that the distributed optical fiber can be integrated into the measured structure more quickly and firmly, and the integration stability of the distributed optical fiber can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the principle of the method of integrating the distributed optical fiber into the structure under test of the present invention; Figure 2 A schematic diagram of an implementation of a method for integrating a distributed optical fiber into a structure under test according to the present invention; Figure 3 This is a schematic diagram of the shape of a distributed optical fiber integrated on a REBCO high-temperature superconducting wire according to Example 2 of the present invention; Figure 4 This is a schematic diagram of the state of the REBCO high-temperature superconducting wire integrated with the distributed optical fiber in Example 1 of the present invention after the alternating load measurement is performed in an extreme low temperature environment; Figure 5 It is a schematic diagram of the state of the REBCO high-temperature superconducting wire integrated with distributed optical fiber in Comparative Example 1 of the present invention after alternating load measurement in an extreme low temperature environment.

[0017] Markings in the figure: 1. Tested structure; 2. High temperature resistant tape; 3. Distributed optical fiber; 4. Liquid flux; 5. Welding gun; 6. Solder layer; 7. Superconducting wire pay-off reel; 8. Distributed optical fiber pay-off reel; 9. Superconducting wire take-up reel; 10. Liquid flux spray gun; 11. Welding gun; 12. REBCO high temperature superconducting wire. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments and accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0020] The present invention provides a method for integrating a distributed optical fiber into a structure to be tested, comprising the following steps: S1. Uniformly apply a layer of solder on the surface of the structure to be tested; S2. Use high temperature resistant tape to lay out welding grooves on the surface of the structure to be tested; S3, placing the distributed optical fiber in the soldering tank, and filling the soldering tank with liquid flux; S4. A layer of solder is pre-applied on the surface of the welding gun, and the welding gun welds the distributed optical fiber to the surface of the structure to be measured.

[0021] It is understandable that pre-coating a layer of solder on the surface of the structure to be measured and pre-hanging a layer of solder on the surface of the welding gun can improve the welding affinity between the distributed optical fiber and the structure to be measured, so that the distributed optical fiber can be welded to the structure to be measured more quickly and more firmly, thereby improving the stability and firmness of the distributed optical fiber integrated into the structure to be measured. By using high-temperature resistant tape to form a welding groove on the structure to be measured, placing the distributed optical fiber in the welding groove and filling it with liquid flux, the distributed optical fiber can be fully wrapped and covered by the liquid flux, so that the distributed optical fiber not only achieves connection with the structure to be measured during welding, but also forms a welding protective layer on its own surface, so that the distributed optical fiber is more stably and firmly attached to the surface of the structure to be measured, which helps to ensure the stability and accuracy of the measurement signal.

[0022] By integrating the distributed optical fiber on the structure under test through the method of the present invention, the integrated stability and firmness of the distributed optical fiber can be improved, and the distributed optical fiber can be effectively prevented from cracking, wrinkling or detaching on the structure under test, especially in extreme multi-field environments such as alternating loads and large temperature changes (400K to 4.2K). At the same time, it can also effectively shorten the time consumed by the integration process, improve the integration efficiency, and be more conducive to industrial actual production applications. The method of integrating the distributed optical fiber on the structure under test of the present invention is particularly suitable for extremely complex multi-field environments such as alternating loads and large temperature changes.

[0023] The principle schematic diagram of the method of integrating the distributed optical fiber into the structure under test of the present invention is as follows Figure 1As shown, a high temperature resistant tape 2 is attached to the structure 1 to be tested, and the high temperature resistant tape 2 is arranged to form a welding groove, the distributed optical fiber 3 is placed in the welding groove, and the welding groove is filled with liquid flux 4, and a layer of solder layer 6 is hung on the surface of the welding gun 5 in advance, and then the distributed optical fiber 3 is welded, so that the distributed optical fiber 3 can be integrated on the structure 1 to be tested. In some embodiments, the specific method of hanging a layer of solder layer 6 on the surface of the gun head of the welding gun 5 in advance is: turn on the welding gun 5, so that the gun head of the welding gun 5 starts to heat, and then insert the welding gun 5 into the tin wire or tin sheet, and gently rub it, so that the molten tin is evenly coated on the gun head of the welding gun 5 to form a layer of solder layer. In order to improve the adhesion of the solder layer, a layer of rosin can also be applied to the gun head of the welding gun 5 before the welding gun 5 contacts the tin wire or tin sheet.

[0024] Specifically, in S1 , the thickness of the solder layer is 0.8 to 1.5 μm, preferably 1 μm.

[0025] Further, in S3, the distributed optical fiber is placed at a central position in the welding groove.

[0026] In some embodiments, the shape of the welding groove includes one or a combination of linear, rectangular, circular, arc or triangular.

[0027] It should be noted that the surface of the distributed optical fiber has a metal and / or metal compound protective layer. In some embodiments, the metal and / or metal compound protective layer includes one of copper and its compounds, gold and its compounds, titanium and its compounds, or nickel and its compounds, preferably copper and its compounds. Coating the surface of the distributed optical fiber with a metal and / or metal compound protective layer can improve the durability, tensile strength, and electromagnetic interference resistance of the distributed optical fiber, and can also play a role in moisture and water resistance, which is conducive to improving the measurement stability and accuracy of the distributed optical fiber.

[0028] As one of the embodiments, the structure to be measured is a superconducting wire or a superconducting coil, preferably a high-temperature superconducting wire. Since the distributed optical fiber itself has a certain ability to resist electromagnetic interference, the method of the present invention is used to integrate the distributed optical fiber on the high-temperature superconducting wire to perform structural health monitoring of the high-temperature superconducting wire, which can further enhance the anti-electromagnetic interference ability of the high-temperature superconducting wire and make the monitoring data more accurate and reliable. At the same time, the distributed optical fiber is attached to the surface of the high-temperature superconducting wire by welding, so that the distributed optical fiber is more sensitive to the temperature changes on the surface of the high-temperature superconducting wire, and can achieve rapid response and accurate measurement, and the measurement results are highly reliable. Since the temperature level at which the high-temperature superconducting wire realizes the superconducting phenomenon is relatively high, it is very important to perform real-time temperature monitoring of the high-temperature superconducting wire. Through real-time temperature monitoring, the stability of the superconducting performance of the high-temperature superconducting wire can be maintained, and it is also beneficial to improve the safety of the use of the high-temperature superconducting wire.

[0029] Furthermore, the method for integrating distributed optical fiber into the structure under test specifically comprises the following steps: S1. Uniformly coat a solder layer on the surface of the superconducting wire; S2, using high temperature resistant tape to lay out welding grooves on the surface of superconducting wire; S3, fixing the distributed optical fiber in the welding groove of the superconducting wire, and spraying liquid soldering flux into the welding groove with a liquid soldering flux spray gun; S4. A layer of solder is pre-applied on the surface of the welding gun, and the welding gun welds the distributed optical fiber to the surface of the superconducting wire.

[0030] As one of the implementation methods, Figure 2 As shown, a superconducting wire is provided by a superconducting wire pay-off reel 7, and a distributed optical fiber pay-off reel 8 is provided to provide a distributed optical fiber. After the superconducting wire completes the welding of the distributed optical fiber, the material is collected by a superconducting wire take-up reel 9, and a liquid flux spray gun 10 and a welding gun 11 are sequentially located in the upper area between the superconducting wire pay-off reel 7 and the superconducting wire take-up reel 9. During the process of spraying liquid flux and welding, the positions of the liquid flux spray gun 10 and the welding gun 11 are fixed and do not move, and the superconducting wire and the distributed optical fiber are synchronously moved under the synchronous operation of the superconducting wire pay-off reel 7 and the distributed optical fiber pay-off reel 8, respectively, and sequentially pass under the liquid flux spray gun 10 and the welding gun 11. It should be noted that after the liquid flux spray gun 10 is started, the welding gun 11 is started again when the superconducting wire and the distributed optical fiber that have completed the liquid flux spraying move to the corresponding position of the welding gun 11.

[0031] Example 1 This embodiment provides a method for integrating a distributed optical fiber into a structure under test, comprising the following steps: S1. Uniformly coating a solder layer with a thickness of 1 μm on the surface of the REBCO high-temperature superconducting wire; S2. Use high temperature resistant tape to lay on the surface of REBCO high temperature superconducting wire to form a straight welding groove; S3, winding the REBCO high-temperature superconducting wire on a pay-off roller to form a superconducting wire pay-off reel, winding the distributed optical fiber coated with a protective layer of copper and its compounds on the pay-off roller to form a distributed optical fiber pay-off reel, fixing the distributed optical fiber at a central position in the welding groove of the REBCO high-temperature superconducting wire, the superconducting wire pay-off reel and the distributed optical fiber pay-off reel are synchronously operated, the REBCO high-temperature superconducting wire and the distributed optical fiber are synchronously moved, the liquid flux spray gun is started, and liquid flux is sprayed into the welding groove; S4. Pre-apply a layer of solder on the surface of the welding gun, start the welding gun, and weld the distributed optical fiber to the surface of the REBCO high-temperature superconducting wire. The REBCO high-temperature superconducting wire with the distributed optical fiber welded is collected through the superconducting wire take-up reel.

[0032] Example 2 This embodiment provides a method for integrating a distributed optical fiber into a structure under test, comprising the following steps: S1. Uniformly coating a solder layer with a thickness of 1 μm on the surface of the REBCO high-temperature superconducting wire; S2. A high temperature resistant tape is used to lay arc, straight and circular welding grooves on the surface of the REBCO high temperature superconducting wire. The schematic diagram of the shape of the distributed optical fiber 3 integrated on the REBCO high temperature superconducting wire 12 is shown in FIG. Figure 3 As shown; S3, winding the REBCO high-temperature superconducting wire on a pay-off roller to form a superconducting wire pay-off reel, winding the distributed optical fiber coated with a protective layer of copper and its compounds on the pay-off roller to form a distributed optical fiber pay-off reel, fixing the distributed optical fiber at a central position in the welding groove of the REBCO high-temperature superconducting wire, the superconducting wire pay-off reel and the distributed optical fiber pay-off reel are synchronously operated, the REBCO high-temperature superconducting wire and the distributed optical fiber are synchronously moved, the liquid flux spray gun is started, and liquid flux is sprayed into the welding groove; S4. Pre-apply a layer of solder on the surface of the welding gun, start the welding gun, and weld the distributed optical fiber to the surface of the REBCO high-temperature superconducting wire. The REBCO high-temperature superconducting wire with the distributed optical fiber welded is collected through the superconducting wire take-up reel.

[0033] Example 3 This embodiment provides a method for integrating a distributed optical fiber into a structure under test, comprising the following steps: S1. Uniformly coating a solder layer with a thickness of 1 μm on the surface of the REBCO high-temperature superconducting wire; S2. Use high temperature resistant tape to lay on the surface of REBCO high temperature superconducting wire to form a straight welding groove; S3, winding the REBCO high-temperature superconducting wire on a pay-off roller to form a superconducting wire pay-off reel, winding the distributed optical fiber coated with a protective layer of gold and its compounds on the pay-off roller to form a distributed optical fiber pay-off reel, fixing the distributed optical fiber at a central position in the soldering tank of the REBCO high-temperature superconducting wire, the superconducting wire pay-off reel and the distributed optical fiber pay-off reel are synchronously operated, the REBCO high-temperature superconducting wire and the distributed optical fiber are synchronously moved, the liquid flux spray gun is started, and liquid flux is sprayed into the soldering tank; S4. Pre-apply a layer of solder on the surface of the welding gun, start the welding gun, and weld the distributed optical fiber to the surface of the REBCO high-temperature superconducting wire. The REBCO high-temperature superconducting wire with the distributed optical fiber welded is collected through the superconducting wire take-up reel.

[0034] Comparative Example 1 This comparative example provides a method for integrating a distributed optical fiber into a structure under test, wherein the distributed optical fiber is directly bonded to a REBCO high-temperature superconducting wire using a low-temperature epoxy resin.

[0035] Test Example 1 In this test example, the REBCO high-temperature superconducting wire integrated with distributed optical fiber in Example 1 and Comparative Example 1 was subjected to alternating load measurement in an extremely low temperature (4.2K) environment. The schematic diagrams of the states of the REBCO high-temperature superconducting wire integrated with distributed optical fiber in Example 1 and Comparative Example 1 after the alternating load measurement in an extremely low temperature environment are shown in FIG. Figure 4 and Figure 5 shown.

[0036] pass Figure 4 and Figure 5 It can be seen that after the alternating load measurement in the extreme low temperature environment, the epoxy resin on the surface of the REBCO high temperature superconducting wire in Comparative Example 1 has obvious fracture and wrinkling, resulting in premature failure of the adhesion of the epoxy resin, which leads to the failure of the distributed optical fiber to provide sufficient measurement data during the entire fatigue life, seriously affecting the reliability of the measurement results. In contrast, the welding position between the distributed optical fiber and the surface of the REBCO high temperature superconducting wire in Example 1 is in good condition, without obvious abnormalities, and the distributed optical fiber integrated on the REBCO high temperature superconducting wire can show high stability and high precision in multiple alternating load measurements, indicating that the method of integrating the distributed optical fiber into the measured structure of the present invention has good reproducibility and stability.

[0037] The above contents are merely examples and illustrations of the structure of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. A method for integrating distributed optical fiber into a structure under test, characterized in that: The following steps are involved: S1. Uniformly apply a layer of solder on the surface of the structure to be tested; S2. Use high temperature resistant tape to lay out welding grooves on the surface of the structure to be tested; S3, placing the distributed optical fiber in the soldering tank, and filling the soldering tank with liquid flux; S4. A layer of solder is pre-applied on the surface of the welding gun, and the welding gun welds the distributed optical fiber to the surface of the structure to be measured.

2. The method for integrating distributed optical fiber into a structure under test according to claim 1, characterized in that: In the above-mentioned S1, the thickness of the solder layer is 0.8-1.5 μm.

3. The method for integrating distributed optical fiber into a structure under test according to claim 1, characterized in that: In S3, the distributed optical fiber is placed in the center of the welding groove.

4. The method for integrating distributed optical fiber into a structure under test according to claim 1, characterized in that: The shape of the welding groove includes one or a combination of straight line, rectangle, ring, arc or triangle.

5. The method for integrating distributed optical fiber into a structure under test according to claim 1, characterized in that: The surface of the distributed optical fiber has a metal and / or metal compound protective layer.

6. The method for integrating distributed optical fiber into a structure under test according to claim 5, characterized in that: The metal and / or metal compound protective layer includes one of copper and its compounds, gold and its compounds, titanium and its compounds, or nickel and its compounds.

7. The method for integrating distributed optical fiber into a structure under test according to claim 1, characterized in that: The structure to be measured is a superconducting wire or a superconducting coil.

8. The method for integrating distributed optical fiber into a structure under test according to claim 7, characterized in that: The specific steps include: S1. Uniformly coat a solder layer on the surface of the superconducting wire; S2, using high temperature resistant tape to lay out welding grooves on the surface of superconducting wire; S3, fixing the distributed optical fiber in the welding groove of the superconducting wire, and spraying liquid soldering flux into the welding groove with a liquid soldering flux spray gun; S4. A layer of solder is pre-applied on the surface of the welding gun, and the welding gun welds the distributed optical fiber to the surface of the superconducting wire.

9. The method for integrating distributed optical fiber into a structure under test according to claim 8, characterized in that: During the process of spraying the liquid soldering flux and welding, the positions of the liquid soldering flux spray gun and the welding gun are fixed, and the superconducting wire and the distributed optical fiber move synchronously.

10. The method for integrating distributed optical fiber into a structure under test according to claim 9, characterized in that: After the liquid soldering flux spray gun is started, the soldering gun is started again when the superconducting wire and the distributed optical fiber that have been sprayed with liquid soldering flux move to the corresponding positions of the soldering gun.

Images