Fiber bragg grating clamping support for pipeline monitoring and strain correction method and equipment

Abstract

The invention discloses a fiber bragg grating clamping support for pipeline monitoring and a strain correction method and device, and relates to the technical field of pipeline monitoring. The fiber bragg grating clamping support comprises a base and a cover plate in butt joint with the base. A first arc-shaped groove is formed in the butt-joint end face of the base, a second arc-shaped groove is formed in the butt-joint end face of the cover plate, and the first arc-shaped groove and the second arc-shaped groove can clamp the fiber bragg grating after being in butt joint; the contact end face of the base and the butt joint end face of the base are oppositely distributed and make contact with a to-be-monitored pipeline, the contact end face is a curved surface, and the curvature of the curved surface is the same as that of the to-be-monitored pipeline. By adopting the fiber bragg grating clamping support, the strain of the to-be-monitored pipeline can be effectively transmitted to the fiber bragg grating, so that the monitoring data of the fiber bragg grating can be conveniently and accurately corrected subsequently, and the monitoring precision is improved.

Description

Technical Field

[0001] The present application relates to the technical field of pipeline monitoring, and in particular to a fiber grating clamping support and a strain correction method and device for pipeline monitoring. Background Art

[0002] As an important part of urban infrastructure, underground pipe network systems include water supply, drainage, gas, electricity, communications and other pipelines. The operation status of these pipelines is directly related to urban operation and the quality of life of residents. Affected by abnormal factors such as concentrated construction loads, uneven ground settlement and pipeline pressure testing, pipelines are prone to deformation or even damage.

[0003] At present, relevant pipeline monitoring methods include manual inspection, electromagnetic method and fiber optic sensing method. Among them, fiber optic sensing method has the advantages of high sensitivity and no electromagnetic interference and is widely used. However, the elastic modulus of pipelines and fiber optic sensors is different, which will cause the strain measured by the fiber optic sensor to be inconsistent with the actual strain of the pipeline, reducing the monitoring accuracy. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the related art, it is desired to provide a fiber grating clamping support and a strain correction method and device for pipeline monitoring, which can improve the monitoring accuracy.

[0005] In a first aspect, the present application provides a fiber Bragg grating clamping support for pipeline monitoring, the fiber Bragg grating clamping support comprising a base and a cover plate connected to the base; The butt joint end surface of the base is provided with a first arc groove, and the butt joint end surface of the cover plate is provided with a second arc groove, and the first arc groove and the second arc groove can clamp the optical fiber Bragg grating after butt joint; The contact end surface of the base and the butt end surface of the base are relatively distributed and in contact with the pipeline to be monitored. The contact end surface is a curved surface, and the curvature of the curved surface is the same as the curvature of the pipeline to be monitored.

[0006] Optionally, in some embodiments of the present application, both the first arc-shaped groove and the second arc-shaped groove are coated with adhesive.

[0007] Optionally, in some embodiments of the present application, the base is made of stainless steel or plastic.

[0008] Optionally, in some embodiments of the present application, a first height h1 between the docking end face of the base and the contact end face of the base is in the range of 70mm≤h1≤75mm, and a second height h2 is in the range of 49mm≤h2≤54mm, and the first height h1 is greater than the second height h2.

[0009] Optionally, in some embodiments of the present application, the contact end surface of the base is bonded or welded to the pipeline to be monitored.

[0010] Optionally, in some embodiments of the present application, first mounting holes are respectively provided on both sides of the first arc-shaped groove on the base, and second mounting holes matching the first mounting holes are respectively provided on both sides of the second arc-shaped groove on the cover plate, and the first mounting hole and the second mounting hole are connected by fasteners.

[0011] In a second aspect, the present application provides a strain correction method for the fiber grating clamping support described in any one of the first aspects, the strain correction method comprising: Obtaining the wavelength variation of the fiber Bragg grating; The wavelength variation is corrected according to the strain transfer coefficient of the clamping support to obtain the strain of the pipeline to be monitored.

[0012] Optionally, the clamping support strain transfer coefficient in some embodiments of the present application is Determined by formula (I): = (I) In formula (I), Indicates different positions along the axis of the fiber Bragg grating; represents the hyperbolic sine function; model coefficient , represents the elastic modulus of the adhesive layer, represents the shear modulus of the adhesive layer, represents the fiber Bragg grating radius, represents the inner radius of the adhesive layer, Indicates the outer radius of the glue layer.

[0013] Optionally, the model coefficients described in some embodiments of the present application are Through formula (II) to formula (VIII), we can obtain: (II) In formula (II), represents the normal stress of the fiber Bragg grating cross section, represents the shear stress distribution on the fiber Bragg grating surface; (III) In formula (III), represents the normal stress in the cross section of the adhesive layer, It represents the shear stress distribution on the adhesive layer surface; Combining formula (II) and formula (III) we can get = (IV) Using the classical shear-lag theory, we get (V) Combining equation (IV) and equation (V), and taking the integral, we can get ) (VI) In formula (VI), represents the internal displacement of the adhesive layer, represents the external displacement of the adhesive layer; Differentiating equation (VI) yields ) (VII) In formula (VII), represents the internal strain of the adhesive layer, represents the external strain of the adhesive layer; Rearranging formula (VII) yields (VIII).

[0014] In a third aspect, the present application provides a terminal device, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the instruction, the program, the code set or the instruction set is loaded and executed by the processor to implement the steps of the strain correction method described in any one of the second aspects.

[0015] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages: The embodiment of the present application provides a fiber Bragg grating clamping support and a strain correction method and device for pipeline monitoring, which firmly clamps the fiber Bragg grating through a first arc groove on the docking end face of the base and a second arc groove on the docking end face of the cover plate to prevent shaking, and a base contact end face arranged opposite to the docking end face of the base directly contacts the pipeline to be monitored, and the base contact end face is a curved surface, and the curvature of the curved surface is the same as the curvature of the pipeline to be monitored, that is, the base and the pipeline to be monitored are tightly fitted, that is, the strain of the pipeline to be monitored can be effectively transmitted to the fiber Bragg grating, which is convenient for subsequent accurate correction of the fiber Bragg grating monitoring data and improves the monitoring accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1A schematic diagram of a three-dimensional structure of a fiber grating clamping support for pipeline monitoring provided in an embodiment of the present application; Figure 2 A schematic diagram of a fiber Bragg grating clamping support in use provided in an embodiment of the present application; Figure 3 A method provided in the embodiment of the present application Figure 1 A schematic diagram of the side structure of the fiber Bragg grating clamping support shown; Figure 4 A schematic flow chart of a strain correction method for a fiber Bragg grating clamping support provided in an embodiment of the present application; Figure 5 A schematic diagram of a mechanical transfer model of a fiber Bragg grating, an adhesive layer and a pipeline to be monitored provided in an embodiment of the present application; Figure 6 A structural block diagram of a terminal device provided in an embodiment of the present application.

[0018] Reference numerals: 1-fiber Bragg grating clamping support, 11-base, 111-first arc-shaped groove, 112-first mounting hole, 12-cover plate, 121-second arc-shaped groove, 122-second mounting hole, a-fiber Bragg grating, b-pipeline to be monitored, h1-first height, h2-second height, 2-terminal device, 21-processor, 22-memory. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Figures 1 to 6 The fiber grating clamping support and strain correction method and equipment for pipeline monitoring provided by the embodiments of the present application are described in detail.

[0022] Please refer to Figure 1, which is a schematic diagram of a three-dimensional structure of a fiber Bragg grating clamping support for pipeline monitoring provided by an embodiment of the present application. The fiber Bragg grating clamping support 1 includes a base 11 and a cover plate 12 connected to the base 11. The butt end surface of the base 11 is provided with a first arc groove 111, and the butt end surface of the cover plate 12 is provided with a second arc groove 121. Figure 2 As shown, the first arc groove 111 and the second arc groove 121 can firmly clamp the fiber Bragg grating a after docking to avoid shaking, and the contact end surface of the base 11 and the docking end surface of the base 11 are relatively distributed and in contact with the pipeline b to be monitored. The contact end surface is a curved surface, and the curvature of the curved surface is the same as the curvature of the pipeline b to be monitored, so that the base 11 and the pipeline b to be monitored can be closely fitted. The advantage of this setting is that the strain of the pipeline b to be monitored can be effectively transmitted to the fiber Bragg grating a, which is convenient for the subsequent accurate correction of the fiber Bragg grating monitoring data and improves the monitoring accuracy. It should be noted that Figure 1 and Figure 2 The curvature of the contact end surface of the middle base 11 may be 5.82 degrees.

[0023] In some embodiments of the present application, for example, the first arc groove 111 and the second arc groove 121 are coated with adhesive, that is, an adhesive layer is formed to further firmly clamp the fiber grating a, and the reliability is strong. For another example, the base 11 is made of stainless steel or plastic. The advantage of such a setting is that the stainless steel material is strong and durable, and has a strong ability to adapt to harsh environments, while the plastic material has the advantage of low manufacturing cost. Figure 3 As shown, the first height h1 between the butt end face of the base 11 and the contact end face of the base 11 is in the range of 70mm≤h1≤75mm, and the second height h2 is in the range of 49mm≤h2≤54mm. The first height h1 is greater than the second height h2, and the structure is compact, saving space resources. Furthermore, the contact end face of the base 11 can be connected to the pipeline b to be monitored by bonding or welding, thereby meeting diverse usage requirements and being more flexible.

[0024] In some embodiments of the present application, first mounting holes 112 are respectively provided on both sides of the first arc-shaped groove 111 on the base 11, and second mounting holes 122 compatible with the first mounting holes 112 are respectively provided on both sides of the second arc-shaped groove 121 on the cover plate 12. The first mounting hole 112 and the second mounting hole 122 are connected by fasteners, for example, the fasteners are bolts, and the model of the bolts is M5 high-strength bolts. At this time, the first mounting hole 112 is a non-through bolt hole, and the second mounting hole 122 is a through bolt hole. The length of the cover plate 12 can be 45 mm and the width can be 31 mm, that is, the docking end face size of the base 11 is 45 mm×31 mm.

[0025] During the actual installation of the fiber grating clamping support 1, the fiber grating a is first placed in the first arc groove 111 of the base 11, and then the cover plate 12 is covered and lightly pressed by hand to ensure that the fiber grating a is completely in the first arc groove 111 and the second arc groove 121; secondly, two M5 high-strength bolts are screwed into the second mounting hole 122 on the upper surface of the cover plate 12, and the bolts are tightened to ensure that the base 11 and the cover plate 12 can tightly clamp the fiber grating a; finally, two or more fiber grating clamping supports 1 are fixed to the outer surface of the pipeline b to be monitored by using high-strength epoxy resin glue.

[0026] The fiber grating clamping support for pipeline monitoring provided in the embodiment of the present application firmly clamps the fiber grating through the first arc groove on the docking end face of the base and the second arc groove on the docking end face of the cover plate to prevent shaking, and the base contact end face arranged opposite to the docking end face of the base directly contacts the pipeline to be monitored, and the base contact end face is a curved surface, and the curvature of the curved surface is the same as the curvature of the pipeline to be monitored, that is, the base and the pipeline to be monitored are tightly fitted, that is, the strain of the pipeline to be monitored can be effectively transmitted to the fiber grating, which is convenient for the subsequent accurate correction of the fiber grating monitoring data, thereby improving the monitoring accuracy.

[0027] Based on the above embodiments, the present application provides a method for Figures 1 to 3 The strain correction method of the fiber Bragg grating clamping support 1 in the corresponding embodiment. Please refer to Figure 4 , which is a schematic flow chart of a strain correction method for a fiber Bragg grating clamping support provided in an embodiment of the present application, and the strain correction method specifically comprises the following steps: S101, obtaining the wavelength change of the fiber grating.

[0028] It should be noted that the core component of the fiber Bragg grating sensor is the fiber Bragg grating, which is a fiber structure with a specific periodic refractive index change. When the fiber Bragg grating is subjected to external strain, its refractive index will change, which will cause the wavelength of the light transmitted in the fiber Bragg grating to change. By measuring this wavelength change, the size and direction of the external strain can be accurately calculated.

[0029] S102, correcting the wavelength variation according to the strain transfer coefficient of the clamping support to obtain the strain of the pipeline to be monitored.

[0030] For example, the strain of the pipeline to be monitored is ,in represents the wavelength change of the fiber Bragg grating, Represents the strain transfer coefficient of the clamping support.

[0031] Furthermore, the clamping support strain transfer coefficient Determined by formula (I): = = (I) In formula (I), Indicates different positions along the axis of the fiber Bragg grating; represents the hyperbolic sine function; model coefficient , represents the elastic modulus of the adhesive layer, Represents the shear modulus of the adhesive layer. If the material is determined, the shear modulus is a constant. represents the fiber Bragg grating radius, represents the inner radius of the adhesive layer, It represents the outer radius of the adhesive layer, and its value is equal to the radius of the pipe to be monitored.

[0032] The model coefficients It can be obtained by formula (II) to formula (VIII), that is, Figure 5 As shown, firstly, the mechanical analysis of the fiber Bragg grating is carried out, and the results are: (II) In formula (II), represents the normal stress of the fiber Bragg grating cross section, It represents the shear stress distribution on the fiber Bragg grating surface; secondly, the influence of the adhesive layer is considered, and then the mechanical analysis of the fiber Bragg grating is performed, and the results are: (III) In formula (III), represents the normal stress in the cross section of the adhesive layer, It represents the shear stress distribution on the adhesive layer surface; Combining equations (II) and (III), since the fiber Bragg grating radius Usually 125um, and , so during the calculation This term can be ignored, giving: = (IV) Using the classical shear-lag theory, we get: (V) Combining formula (IV) and formula (V), , and Taking the integral we get: ) (VI) In formula (VI), represents the internal displacement of the adhesive layer, represents the external displacement of the adhesive layer, and the directions of the internal displacement and the external displacement are away from the fiber Bragg grating and make it tensile; For formula (VI) Taking the derivative we get: ) (VII) In formula (VII), represents the internal strain of the adhesive layer, represents the external strain of the adhesive layer; Arranging formula (VII) yields: (VIII).

[0033] The strain correction method for the fiber Bragg grating clamping support provided in the embodiment of the present application firmly clamps the fiber Bragg grating through the first arc groove on the docking end face of the base and the second arc groove on the docking end face of the cover plate to prevent shaking, and the base contact end face arranged opposite to the docking end face of the base directly contacts the pipeline to be monitored, and the base contact end face is a curved surface, and the curvature of the curved surface is the same as the curvature of the pipeline to be monitored, that is, the base and the pipeline to be monitored are tightly fitted, that is, the strain of the pipeline to be monitored can be effectively transmitted to the fiber Bragg grating, so that the fiber Bragg grating monitoring data can be corrected conveniently and accurately, thereby improving the monitoring accuracy.

[0034] As another aspect, the present application embodiment provides a terminal device. Figure 6 The terminal device 2 may include a processor 21 and a memory 22. For example, the terminal device 2 is a handheld terminal. The memory 22 stores at least one instruction, at least one program, code set or instruction set. The instruction, program, code set or instruction set is loaded and executed by the processor 21 to implement Figures 4 to 5 The steps of the strain correction method in the corresponding embodiment.

[0035] As another aspect, the present invention provides a computer-readable storage medium for storing program code for executing Figures 4 to 5 The steps of the strain correction method in the corresponding embodiment.

[0036] Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the strain correction method of the embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0037] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0038] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A fiber grating clamping support for pipeline monitoring, characterized in that: The optical fiber Bragg grating clamping support (1) comprises a base (11) and a cover plate (12) connected to the base (11); The butt joint end surface of the base (11) is provided with a first arc-shaped groove (111), and the butt joint end surface of the cover plate (12) is provided with a second arc-shaped groove (121), and the first arc-shaped groove (111) and the second arc-shaped groove (121) can clamp the optical fiber Bragg grating (a) after being butt jointed; The contact end surface of the base (11) and the butt end surface of the base (11) are arranged relative to each other and are in contact with the pipeline (b) to be monitored. The contact end surface is a curved surface, and the curvature of the curved surface is the same as the curvature of the pipeline (b) to be monitored.

2. The fiber Bragg grating clamping support according to claim 1, characterized in that: The first arc-shaped groove (111) and the second arc-shaped groove (121) are both coated with adhesive.

3. The fiber Bragg grating clamping support according to claim 1, characterized in that: The base (11) is made of stainless steel or plastic.

4. The fiber Bragg grating clamping support according to claim 3, characterized in that: A first height h1 between the butting end surface of the base (11) and the contact end surface of the base (11) is in the range of 70 mm ≤ h1 ≤ 75 mm, and a second height h2 is in the range of 49 mm ≤ h2 ≤ 54 mm, wherein the first height h1 is greater than the second height h2.

5. The fiber Bragg grating clamping support according to claim 3, characterized in that: The contact end surface of the base (11) is bonded or welded to the pipeline (b) to be monitored.

6. The fiber Bragg grating clamping support according to any one of claims 1 to 5, characterized in that: First mounting holes (112) are respectively provided on both sides of the first arc-shaped groove (111) on the base (11), and second mounting holes (122) matching the first mounting holes (112) are respectively provided on both sides of the second arc-shaped groove (121) on the cover plate (12), and the first mounting hole (112) and the second mounting hole (122) are connected by fasteners.

7. A strain correction method for the fiber Bragg grating clamping support according to any one of claims 1 to 6, characterized in that: The strain correction method comprises: Obtaining the wavelength variation of the fiber Bragg grating; The wavelength variation is corrected according to the strain transfer coefficient of the clamping support to obtain the strain of the pipeline to be monitored.

8. The strain correction method according to claim 7, characterized in that: The clamping support strain transfer coefficient Determined by formula (I): = （Ⅰ） In formula (I), Indicates different positions along the axis of the fiber Bragg grating; represents the hyperbolic sine function; model coefficient , represents the elastic modulus of the adhesive layer, represents the shear modulus of the adhesive layer, represents the fiber Bragg grating radius, represents the inner radius of the adhesive layer, Indicates the outer radius of the glue layer.

9. The strain correction method according to claim 8, characterized in that: The model coefficients Through formula (II) to formula (VIII), we can obtain: （Ⅱ） In formula (II), represents the normal stress of the fiber Bragg grating cross section, represents the shear stress distribution on the fiber Bragg grating surface; （Ⅲ） In formula (III), represents the normal stress in the cross section of the adhesive layer, It represents the shear stress distribution on the adhesive layer surface; Combining formula (II) and formula (III) we can get = （Ⅳ） Using the classical shear-lag theory, we get （Ⅴ） Combining equation (IV) and equation (V), and taking the integral, we can get ) （Ⅵ） In formula (VI), represents the internal displacement of the adhesive layer, represents the external displacement of the adhesive layer; Differentiating equation (VI) yields ) （Ⅶ） In formula (VII), represents the internal strain of the adhesive layer, represents the external strain of the adhesive layer; Rearranging formula (VII) yields （Ⅷ）。 10. A terminal device, characterized in that: The terminal device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the instruction, the program, the code set or the instruction set is loaded and executed by the processor to implement the steps of the strain correction method described in any one of claims 7 to 9.

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