Fiber grating sensor anti-overload protection device

Abstract

The application provides a kind of fiber grating sensor overload protection device, belongs to the technical field of optical fiber sensor, including guide rail, sliding block, fiber grating sensor, sensing fiber loop and reserved optical fiber, sliding block is slidably connected with guide rail, and fiber grating sensor is connected with metal roof and sliding block to form long scale fixed point at both ends;Sensing fiber loop is threaded through sliding block, and both ends are connected with metal roof and metal roof across middle area, and fiber grating sensor is connected with sensing fiber loop;Reserved optical fiber is connected with fiber grating sensor through optical cable at one end, and connected with acquisition end through optical cable at the other end;When fiber grating sensor is overloaded, sliding block is unlocked with guide rail to release redundant length of fiber grating sensor and protect fiber grating sensor.The fiber grating sensor overload protection device provided by the application has the structure that can make fiber grating sensor suitable for high-precision monitoring of metal roof and may occur large displacement, and has the technical effect of preventing overload.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensor technology, and more specifically, relates to an overload protection device for fiber Bragg grating sensors. Background Technology

[0002] In researching how to achieve integrated monitoring and reinforcement of metal roofs, it was found that existing fiber optic grating sensors are not suitable for structures like metal roofs that require high-precision monitoring and are prone to large displacements. Therefore, to expand the application scenarios of fiber optic sensors to metal roof structures and similar scenarios, there is an urgent need to design a fiber optic overload protection device. For example, in metal roof health monitoring, this device could achieve accurate monitoring of metal roofs under light winds and temperature loads, and could promptly release the fiber optic cable in strong winds, improving the utilization efficiency of the fiber optic sensor. Similar structural safety issues exist in other engineering scenarios, such as stress concentration in pipelines due to foundation settlement and fatigue damage to cables caused by vibration. These scenarios all require long-term monitoring of structural displacement or strain, but existing sensors often struggle to adapt to large displacement or dynamic impact environments, limiting the reliability and economy of the monitoring system.

[0003] Existing overload prevention devices for fiber Bragg grating sensors, or those with overload protection functions, mostly rely on computer warnings (e.g., Chinese patent CN204241077U, which discloses a fiber Bragg grating weighing sensor with overload protection). This overload prevention method cannot provide timely protection for the fiber Bragg grating sensor; it only relies on computer system alerts and cannot address overloads caused by continuous external loads. Summary of the Invention

[0004] The purpose of this invention is to provide an overload protection device for fiber Bragg grating sensors, which aims to solve the technical problem that existing fiber Bragg grating sensors are not suitable for high-precision monitoring of metal roof structures that may experience large displacements.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide an overload protection device for fiber optic grating sensors, comprising:

[0006] Guide rails are used to connect to the metal roof.

[0007] A slider is slidably connected to the guide rail and has a sliding degree of freedom along the length of the guide rail;

[0008] A fiber optic grating sensor has one end connected to a metal roof and the other end connected to the slider, with long gauge fixed points formed at both ends of the fiber optic grating sensor.

[0009] The sensing fiber optic loop passes through the slider, with one end connected to the metal roof and the other end used to connect to the next fiber Bragg grating sensor or the mid-span area of ​​the metal roof. The end of the fiber Bragg grating sensor away from the slider is connected to the end of the sensing fiber optic loop connected to the metal roof via an optical cable.

[0010] A fiber optic cable is reserved, with one end connected to the fiber optic grating sensor near the slider via an optical cable, and the other end connected to the acquisition end via another optical cable.

[0011] The slider has a first state locked to the guide rail and a second state slidably connected to the guide rail. When the fiber Bragg grating sensor is overloaded, the slider is released from the guide rail and switches to the second state to release the redundant length of the fiber Bragg grating sensor and protect the fiber Bragg grating sensor.

[0012] In one possible implementation, the upper end of the guide rail is provided with a plurality of pin holes at equal intervals along its length, the slider has a cavity inside, and a pin is connected inside the cavity. The pin is inserted into one of the pin holes to form a first state, and the pin is pulled out from the pin hole to form a second state.

[0013] In one possible implementation, the depth direction of the pin hole is along the height direction of the guide rail, and the guide rail has tracks on both sides along its length direction, with the bottom sides of the slider slidably connected to the tracks on both sides respectively.

[0014] In one possible implementation, the slider includes:

[0015] The outer shell has the cavity formed inside, and the bottom is slidably connected to the guide rail;

[0016] A return spring is connected at its upper end to the top of the inner side of the cavity of the outer shell, and the elastic extension and contraction direction of the return spring is along the height direction of the outer shell;

[0017] The pin fixing post is hollow inside and its upper end is fixedly connected to the top of the inner side of the outer shell. The side of the pin fixing post has a square hole that passes through its interior and exterior. The other side of the pin fixing post opposite to the square hole has an optical fiber loop connection hole, through which the sensing optical fiber loop passes.

[0018] A lever is located inside the pin fixing post. The bottom of the lever is inserted into the square hole and the end extends to the outside of the pin fixing post. The bottom of the lever is fixedly connected to the sensing fiber optic circuit.

[0019] The pin is hollow inside, and the lower end of the pin fixing post is inserted into the pin. One end of the lever extending from the pin fixing post abuts against the upper end of the pin to limit the upward movement of the pin. The lower end of the return spring is connected to the pin and is used to pull the pin and give the pin an upward driving force. When the fiber Bragg grating sensor is overloaded, the sensing fiber circuit pulls the lever to move into the pin fixing post, so that the lever retracts into the pin fixing post and leaves the pin. The pin moves upward with the help of the return spring, thereby disengaging the pin from the pin hole. The slider is in a second state to release the redundant length of the fiber Bragg grating sensor and protect the fiber Bragg grating sensor.

[0020] In one possible implementation, the pin fixing post has a space inside suitable for the paddle to move in the radial plane of the pin fixing post. The paddle includes a vertical plate arranged along the axial direction of the pin fixing post and a horizontal plate fixed at one end to the bottom of the vertical plate and arranged perpendicular to the vertical plate. The other end of the horizontal plate is inserted into the square hole and extends to the outside of the pin fixing post, while the bottom end abuts against the upper end of the pin to restrict the pin from moving upward.

[0021] In one possible implementation, the side of the pin has an elongated through hole arranged parallel to the pin axis, the upper end of the elongated through hole extending to the upper end of the pin to form an optical fiber channel, the optical fiber channel being used to allow the sensing optical fiber circuit to enter when the pin moves upward, so that the pin avoids the sensing optical fiber circuit.

[0022] In one possible implementation, a small hole is provided on the side of the housing, through which the sensing fiber optic loop passes.

[0023] In one possible implementation, the acquisition end includes a fiber Bragg grating demodulator and a computer.

[0024] In one possible implementation, the fiber Bragg grating sensor has the same length as the sensing fiber loop and is subjected to the same force.

[0025] In one possible implementation, both the fiber Bragg grating sensor and the sensing fiber loop are connected to a protective layer.

[0026] The beneficial effects of the fiber Bragg grating sensor overload protection device provided by this invention are as follows: Compared with the prior art, the fiber Bragg grating sensor overload protection device of this invention includes a guide rail, a slider, a fiber Bragg grating sensor, a sensing fiber optic loop, and a reserved fiber optic cable. The guide rail is connected to a metal roof, and the slider is slidably connected to the guide rail. One end of the fiber Bragg grating sensor is connected to the metal roof, and the other end is connected to the slider. Long gauge-length fixed points are formed at both ends of the fiber Bragg grating sensor. The sensing fiber optic loop passes through the slider, with one end connected to the metal roof and the other end used to connect to the next fiber Bragg grating sensor or the mid-span area of ​​the metal roof. One end of the fiber Bragg grating sensor is connected to the sensing fiber optic loop via an optical cable, which is then connected to the metal roof. One end of a pre-installed optical fiber is connected to one end of the fiber Bragg grating sensor via an optical cable, and the other end is connected to the acquisition end via an optical cable. When the fiber Bragg grating sensor is overloaded, the slider releases its lock to the guide rail, releasing the redundant length of the fiber Bragg grating sensor and protecting the sensor. This solves the technical problem that fiber Bragg grating sensors are not suitable for high-precision monitoring of metal roofs and structures that may experience large displacements. It effectively enables fiber Bragg grating sensors to be used for high-precision monitoring of metal roofs and structures that may experience large displacements, while preventing overload. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of an overload protection device for a fiber Bragg grating sensor provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the slider and guide rail of an overload protection device for a fiber Bragg grating sensor provided in an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the slider structure of an overload protection device for a fiber Bragg grating sensor provided in an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of the internal structure of the slider of an overload protection device for a fiber Bragg grating sensor provided in an embodiment of the present invention;

[0032] Figure 5 for Figure 4 A three-dimensional structural diagram of the latch in the middle;

[0033] Figure 6 for Figure 4 Main view of the structure of the pin fixing post;

[0034] Figure 7 A schematic diagram of the guide rail structure of an overload protection device for a fiber Bragg grating sensor provided in an embodiment of the present invention;

[0035] Figure 8 A flowchart illustrating the working process of an overload protection device for a fiber Bragg grating sensor provided in this embodiment of the invention;

[0036] Figure 9 This is a schematic diagram illustrating the application of a fiber Bragg grating sensor overload protection device in a metal roof, as provided in an embodiment of the present invention.

[0037] Figure 10 The flowchart of the fiber Bragg grating overload protection algorithm of a fiber Bragg grating sensor overload protection device provided in this embodiment of the invention is shown.

[0038] Explanation of reference numerals in the attached figures:

[0039] 10. Guide rail; 11. Pin hole; 12. Track; 20. Slider; 21. Pin; 22. Housing; 23. Return spring; 24. Pin fixing post; 25. Paddle; 26. Square hole; 27. Fiber optic loop connection hole; 28. Fiber optic channel; 29. ​​Small hole; 210. Spring fixing seat; 30. Fiber optic grating sensor; 40. Sensing fiber optic loop; 50. Reserved fiber optic cable; 60. Metal roof; 70. Acquisition end; 80. Mid-span area. Detailed Implementation

[0040] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0041] This invention addresses the technical bottlenecks mentioned in the background by proposing an overload protection device for fiber Bragg grating (FBG) sensors. By integrating a mechanical slider-guide rail mechanism with fiber optic sensing (FBG sensor) technology, this device can adjust the stress state of the sensor (FBG sensor) in a timely manner during monitoring. For example, when wind load causes the metal roof panel to displace beyond the limit, the device automatically releases the redundant length of the sensor through a spring-pin linkage mechanism, preventing the FBG from breaking due to overload while maintaining the continuity of the monitoring signal. Its modular design can also be extended to scenarios such as pipeline settlement and cable vibration. Through distributed networking, it can achieve multi-point collaborative monitoring, providing an efficient and durable solution for the health diagnosis and risk prevention of engineering structures, and expanding the application scenarios of FBG sensors. It can ensure distributed sensing FBG monitoring while timely releasing the sensor in windy weather, effectively protecting the distributed sensing FBG sensor and enabling the sensing FBG to be reused multiple times. This invention is applicable to, but not limited to, metal roof systems and can be used in any scenario requiring accurate monitoring and potentially involving large displacements, such as pipeline vibration and settlement, and cables.

[0042] Please refer to the following: Figures 1 to 10 This invention provides an overload protection device for a fiber Bragg grating sensor. The device includes a guide rail 10, a slider 20, a fiber Bragg grating sensor 30, a sensing fiber optic loop 40, and a reserved fiber optic cable 50. The guide rail 10 is connected to a metal roof 60; the slider 20 is slidably connected to the guide rail 10 and has a degree of freedom to slide along the length of the guide rail 10; one end of the fiber Bragg grating sensor 30 is connected to the metal roof 60 (connection position is...). Figure 1 The middle part is located at the position indicated by the dotted circle on the upper right side), and the other end is connected to slider 20 (the connection position is...). Figure 1 The position is indicated by the dashed circle at the upper right end of slider 20. Long gauge-length fixed points are formed at both ends of fiber Bragg grating sensor 30. Sensing fiber optic loop 40 passes through slider 20, with one end connected to metal roof 60 (connection location is...). Figure 1 The position indicated by the dashed circle on the lower right side), the other end is used to connect to the next fiber Bragg grating sensor 30 (in Figure 1 The connection position is not shown in the diagram. Figure 1 The area indicated by 80) or the metal roof 60 spanning the area 80, the fiber optic grating sensor 30 at the end furthest from the slider 20 (referring to the area indicated by 80) Figure 1 The location indicated by the dotted circle at the top right of the center) is accessed via optical fiber (referring to...) Figure 1 The curved line located between the upper and lower dashed circles on the right side) connects to the sensing fiber optic loop 40 and to one end of the metal roof 60 (the connection position is...). Figure 1(The position is indicated by the dashed circle on the lower right side); one end of the reserved optical fiber 50 is connected to the end of the fiber optic grating sensor 30 near the slider 20 via an optical cable, and the other end is connected to the acquisition end 70 via another optical cable; wherein, the slider 20 has a first state locked to the guide rail 10 and a second state slidably connected to the guide rail 10. When the fiber optic grating sensor 30 is overloaded, the slider 20 is released from the lock to the guide rail 10 and switches to the second state to release the redundant length of the fiber optic grating sensor 30 and protect the fiber optic grating sensor 30.

[0043] This invention provides an overload protection device for a fiber Bragg grating sensor. Compared with existing technologies, the slider 20 is slidably connected to the guide rail 10. The two ends of the fiber Bragg grating sensor 30 are respectively connected to the metal roof 60 and the slider 20 to form long gauge fixed points. The sensing fiber loop 40 passes through the slider 20, with its two ends connected to the metal roof 60 and the mid-span area of ​​the metal roof 60, respectively. The fiber Bragg grating sensor 30 is connected to the sensing fiber loop 40. One end of the reserved fiber optic cable is connected to the fiber Bragg grating sensor 30, and the other end is connected to the acquisition end 70. When the fiber Bragg grating sensor 30 is overloaded, the slider 20 is released from locking with the guide rail 10 to release the redundant length of the fiber Bragg grating sensor 30 and protect the fiber Bragg grating sensor 30. This invention provides an overload protection device for a fiber Bragg grating sensor, which enables the fiber Bragg grating sensor 30 to be used for high-precision monitoring of the metal roof 60 while preventing large displacements, thus preventing overload.

[0044] In this embodiment, the bottom end of the guide rail 10 is fixedly connected to the metal roof 60. Mounting holes are provided on the guide rail 10, allowing bolts to be passed through them to fix the guide rail 10 to the upper end of the metal roof 60. The slider 20 slides into the guide rail 10 from one end, achieving a sliding connection. In actual use, the slider 20 will not slip off the guide rail 10, ensuring effective protection of the fiber Bragg grating sensor 30. The reserved optical fiber 50 has a certain length and can be relaxed or extended to a certain distance. Under normal circumstances, it is in a non-extended state. When the fiber Bragg grating sensor 30 encounters an overload, the sensing fiber circuit 40 triggers the slider 20 to slide. After sliding, the slider 20 releases the redundant length of the fiber Bragg grating sensor 30, thus protecting or shielding the fiber Bragg grating sensor 30. The fiber Bragg grating sensor 30 in this embodiment is existing technology and has a certain length. When encountering an overload, one end of the fiber Bragg grating sensor 30 can move or slide, thus releasing the redundant length of the fiber Bragg grating sensor 30. Under normal circumstances, slider 20 is in the first state, that is, the length of fiber optic grating sensor 30 is fixed. When an overload occurs, it can switch from the first state to the second state. The switching action is triggered by sensing fiber optic circuit 40.

[0045] The long gauge length fixing point and the fixing point between one end of the sensing fiber optic loop 40 and the metal roof 60 can be fixed with epoxy resin or structural adhesive. Armored optical cable can be used. The length of the reserved optical fiber 50 can be determined according to actual needs, and calculations will ensure sufficient elongation of the sensing fiber Bragg grating.

[0046] To achieve the sliding connection and mutual locking between the slider 20 and the guide rail 10, in some embodiments, please refer to... Figure 1 , Figure 2 and Figure 7 The upper end of the guide rail 10 is provided with multiple pin holes 11 evenly spaced along its length. A cavity is formed inside the slider 20, and a pin 21 is connected inside the cavity. The pin 21 is inserted into one of the pin holes 11 to form a first state, and pulled out of the pin hole 11 to form a second state. In this embodiment, three pin holes 11 are provided on the guide rail 10, and the pin 21 can be inserted into any one of them, thus limiting the slider 20. This limits the position of the fiber Bragg grating sensor 30 and locks its length. When the fiber Bragg grating sensor 30 is in an overload state, the slider 20 can be released from the guide rail 10, thereby releasing the redundant length of the fiber Bragg grating sensor 30 and protecting it.

[0047] In some embodiments, please refer to Figure 1 , Figure 2 and Figure 7 The depth direction of the pin hole 11 is along the height direction of the guide rail 10. The guide rail 10 has tracks 12 on both sides along its length direction. The bottom sides of the slider 20 are slidably connected to the tracks 12 on both sides. The pin hole 11 is located at the upper end of the guide rail 10. When the guide rail 10 is horizontal, the pin hole 11 can be vertically positioned with its depth direction along the vertical direction. The pin 21 moves up and down or moves along the vertical direction. When the pin 21 is inserted into the pin hole 11, it is in the first state. When the pin 21 is pulled out of the pin hole 11, it is in the second state. In this embodiment, the slider 20 switches from the first state to the second state to release the redundant length of the fiber optic grating sensor 30. There are two sets of tracks 12, which are respectively located on both sides of the guide rail 10. One end of the track 12 extends to one end of the guide rail 10, and the second end of the track 12 does not extend to the other end of the guide rail 10. The slider 20 slides into the guide rail 10 from one end of the track 12, thus realizing the sliding connection between the slider 20 and the guide rail 10.

[0048] In some embodiments, please refer to Figure 1 , Figures 3 to 7The slider 20 includes a housing 22, a return spring 23, a pin fixing post 24, and a lever 25. The housing 22 has an internal cavity, with a guide rail 10 slidably connected to its bottom. The upper end of the return spring 23 is connected to the top of the inner side of the cavity of the housing 22, and the elastic extension direction of the return spring 23 is along the height direction of the housing 22. The pin fixing post 24 is hollow inside, with its upper end fixedly connected to the top of the inner side of the housing 22. A square hole 26 is provided on the side of the pin fixing post 24, penetrating its interior and exterior. On the other side of the pin fixing post 24 opposite to the square hole 26, there is a fiber optic loop connection hole 27 through which the sensing fiber optic loop 40 passes. The lever 25 is located inside the pin fixing post 24, with its bottom inserted into the square hole 26 and its end extending to the outside of the pin fixing post 24. The bottom of the lever 25 is fixed... The sensing fiber optic circuit 40 is fixedly connected; wherein, the inside of the pin 21 is hollow, the lower end of the pin fixing post 24 is inserted into the inside of the pin 21, the end of the lever 25 extending out of the pin fixing post 24 abuts against the upper end of the pin 21 to limit the upward movement of the pin 21, the lower end of the return spring 23 is connected to the pin 21 and is used to pull the pin 21 and give the pin 21 an upward driving force. When the fiber Bragg grating sensor 30 is overloaded, the sensing fiber optic circuit 40 pulls the lever 25 to move into the pin fixing post 24, so that the lever 25 retracts into the pin fixing post 24 and leaves the pin 21. The pin 21 moves upward with the help of the return spring 23, thereby causing the pin 21 to disengage from the pin hole 11. The slider 20 is in the second state to release the redundant length of the fiber Bragg grating sensor 30 and protect the fiber Bragg grating sensor 30. The outer shell 22 is U-shaped, and the bottom is two symmetrical L-shaped and can slide with the track 12, that is, the bottom side wall of the L-shape slides in contact with the track 12. Two return springs 23 are respectively located on both sides of the pin fixing post 24. The pin 21 is located below the pin fixing post 24, and the two are coaxially arranged. The two return springs 23 can simultaneously pull the pin fixing post 24 upward, thereby pulling the pin 21 out of the pin hole 11, i.e., switching to the second state. The sensing fiber optic circuit 40 passes through the housing 22 and the pin fixing post 24 inside it, and is fixedly connected to the bottom end of the lever 25. During the upward movement of the pin 21, it can avoid the sensing fiber optic circuit 40. The lever 25 is inside the pin fixing post 24 and has the freedom of movement within the cross-sectional area of ​​the pin fixing post 24, so that the lever 25 can slide in the square hole 26, thereby disengaging from the pin 21, and causing the pin 21 to move upward under the elastic pull of the return springs 23. The height of the square hole 26 is the same as the height of the fiber optic circuit connection hole 27. The sensing fiber optic loop 40 passes through the fiber optic loop connection hole 27 and the square hole 26. When the fiber optic grating sensor 30 is overloaded, the sensing fiber optic loop 40 moves and pulls the lever 25 to disengage the lever 25 from the pin 21, thus releasing the lock on the pin 21. At this time, the slider 20 can slide on the guide rail 10.

[0049] Specifically, the connection between the sensing fiber optic loop 40 and the lever 25 can be fixed with epoxy resin or structural adhesive. The thickness of the lever 25 needs to be determined by calculation, which is related to the fiber type and the material of the lever 25, and the purpose is to precisely control the stress on the fiber. Two spring fixing seats 210 are provided on both sides of the pin 21 to fix the lower ends of the two return springs 23 respectively.

[0050] The thickness of the lever 25 is precisely designed according to the fiber type to control the triggering force. The length of the reserved fiber 50 is calculated to ensure sufficient buffering of elongation. The mechanical linkage mechanism of this invention not only ensures the continuity of real-time monitoring, but also protects the fiber optic grating sensor 30. Its modular structure can also be extended to distributed monitoring of large displacement scenarios such as pipeline settlement and cable vibration.

[0051] Specifically, the return spring 23 is under tension during use, and its stiffness should not be too large or too small. It should be just enough to pull the pin 21 upwards. The height and width of the lever 25 can be determined based on the pin fixing post 24, and its thickness should be determined by the following calculations: Taking Corning SMF-28e optical fiber (a type of single-mode fiber widely used in communication networks) as an example, according to literature, the tensile force it should withstand should ideally not exceed 3N. Therefore, according to the cantilever beam deflection formula:

[0052] (1)

[0053] in, Take 3N, moment of inertia of section ( For width, (for thickness), Substituting into the deflection formula and rearranging, we get:

[0054] (2)

[0055] Please refer to Figure 10 In the algorithm flow, the initial wavelength A should also include data such as sensor location and number, so as to issue a warning in time when the system finds that the wavelength of a certain sensor has remained unchanged for a long time and is equal to the initial value. The warning should include wavelength, number, and sensor location to facilitate timely maintenance of the structure and sensor.

[0056] The overload protection device (excluding the spring) can be made using 3D printer materials. It can be made in batches using high-precision and high-performance photosensitive resin and then assembled with high-strength glue, or it can be directly printed as a whole.

[0057] In some embodiments, please refer to Figures 3-7The pin fixing post 24 has internal space suitable for the movement of the lever 25 within the radial plane of the pin fixing post 24. The lever 25 includes a vertical plate arranged along the axial direction of the pin fixing post 24 and a horizontal plate fixed at one end to the bottom of the vertical plate and arranged perpendicular to the vertical plate. The other end of the horizontal plate is inserted into the square hole 26 and extends to the outside of the pin fixing post 24, while the bottom end abuts against the upper end of the pin 21 to limit the upward movement of the pin 21. The lever 25 is L-shaped, that is, the horizontal plate and the vertical plate form the lever 25, which can achieve abutment and limit the upper end of the pin 21, and can also release the limit on the pin 21, so that the slider 20 can slide on the guide rail 10, which is the second state.

[0058] To avoid the sensing fiber optic loop 40, in some embodiments, please refer to... Figures 3 to 6 The pin 21 has an elongated through-hole parallel to its axial direction on its side. The upper end of the elongated through-hole extends to the upper end of the pin 21 to form an optical fiber channel 28. The optical fiber channel 28 is used to allow the sensing optical fiber circuit 40 to enter when the pin 21 moves upward, so that the pin 21 avoids the sensing optical fiber circuit 40. During the upward movement of the pin 21, the sensing optical fiber circuit 40 will enter the optical fiber channel 28. Optical fiber channels are provided on both sides of the pin 21 to allow the sensing optical fiber circuit 40 to pass through.

[0059] In some embodiments, please refer to Figures 1 to 3 The outer casing 22 has a small hole 29 on its side, through which the sensing fiber optic circuit 40 passes. The sensing fiber optic circuit 40 passes through the small holes 29 on both sides of the outer casing 22, passes through the fiber optic circuit connection hole 27 inside the outer casing 22, and is fixedly connected to the bottom of the lever 25.

[0060] In some embodiments, please refer to Figure 1 The acquisition end 70 includes a fiber Bragg grating demodulator and a computer. Fiber optic data obtained through the acquisition end 70, processed by a corresponding algorithm, can promptly detect overload locations and pinpoint the overload point. The algorithm can employ existing technology to release redundant length when the overload reaches a threshold, thus protecting the fiber Bragg grating sensor 30.

[0061] In some embodiments, please refer to Figure 1The fiber Bragg grating sensor 30 has the same length as the sensing fiber loop 40 and experiences equal stress. Both the fiber Bragg grating sensor 30 and the sensing fiber loop 40 are connected to a protective layer. Different protective layers, such as Kevlar fiber, carbon fiber, or basalt fiber braided tubing, are used for the fiber Bragg grating sensor 30 and the sensing fiber loop 40 depending on the application scenario. When the metal roof panel 60 shifts due to strong winds, and the stress on the fiber Bragg grating sensor 30 and the sensing fiber loop 40 reaches a preset value, the lever 25 is pulled, causing the pin 21 to move upward under the action of the return spring 23, pulling it out of the pin hole 11. This allows the slider 20 to slide on the guide rail 10, releasing redundant length and preventing the fiber Bragg grating sensor 30 from breaking due to overload.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An overload protection device for a fiber Bragg grating sensor, characterized in that, include: Guide rails are used to connect to the metal roof. A slider is slidably connected to the guide rail and has a sliding degree of freedom along the length of the guide rail; A fiber optic grating sensor has one end connected to a metal roof and the other end connected to the slider, with long gauge fixed points formed at both ends of the fiber optic grating sensor. The sensing fiber optic loop passes through the slider, with one end connected to the metal roof and the other end used to connect to the next fiber Bragg grating sensor or the mid-span area of ​​the metal roof. The end of the fiber Bragg grating sensor away from the slider is connected to the end of the sensing fiber optic loop connected to the metal roof via an optical cable. A fiber optic cable is reserved, with one end connected to the fiber optic grating sensor near the slider via an optical cable, and the other end connected to the acquisition end via another optical cable. The slider has a first state locked to the guide rail and a second state slidably connected to the guide rail. When the fiber Bragg grating sensor is overloaded, the slider is released from the guide rail and switches to the second state to release the redundant length of the fiber Bragg grating sensor and protect the fiber Bragg grating sensor.

2. The fiber optic grating sensor overload protection device as described in claim 1, characterized in that, The upper end of the guide rail is provided with a plurality of pin holes at equal intervals along its length. The slider has a cavity inside, and a pin is connected inside the cavity. The pin is inserted into one of the pin holes to form a first state, and the pin is pulled out from the pin hole to form a second state.

3. The fiber optic grating sensor overload protection device as described in claim 2, characterized in that, The depth direction of the pin hole is along the height direction of the guide rail, and the guide rail has tracks on both sides along its length direction. The bottom sides of the slider are slidably connected to the tracks on both sides.

4. The fiber optic grating sensor overload protection device as described in claim 2, characterized in that, The slider includes: The outer shell has the cavity formed inside, and the bottom is slidably connected to the guide rail; A return spring is connected at its upper end to the top of the inner side of the cavity of the outer shell, and the elastic extension and contraction direction of the return spring is along the height direction of the outer shell; The pin fixing post is hollow inside and its upper end is fixedly connected to the top of the inner side of the outer shell. The side of the pin fixing post has a square hole that passes through its interior and exterior. The other side of the pin fixing post opposite to the square hole has an optical fiber loop connection hole, through which the sensing optical fiber loop passes. A lever is located inside the pin fixing post. The bottom of the lever is inserted into the square hole and the end extends to the outside of the pin fixing post. The bottom of the lever is fixedly connected to the sensing fiber optic circuit. The pin is hollow inside, and the lower end of the pin fixing post is inserted into the pin. One end of the lever extending from the pin fixing post abuts against the upper end of the pin to limit the upward movement of the pin. The lower end of the return spring is connected to the pin and is used to pull the pin and give the pin an upward driving force. When the fiber Bragg grating sensor is overloaded, the sensing fiber circuit pulls the lever to move into the pin fixing post, so that the lever retracts into the pin fixing post and leaves the pin. The pin moves upward with the help of the return spring, thereby disengaging the pin from the pin hole. The slider is in a second state to release the redundant length of the fiber Bragg grating sensor and protect the fiber Bragg grating sensor.

5. The fiber optic grating sensor overload protection device as described in claim 4, characterized in that, The pin fixing post has a space inside suitable for the paddle to move in the radial plane of the pin fixing post. The paddle includes a vertical plate arranged along the axial direction of the pin fixing post and a horizontal plate fixed at one end to the bottom of the vertical plate and arranged perpendicular to the vertical plate. The other end of the horizontal plate is inserted into the square hole and extends to the outside of the pin fixing post, while the bottom end abuts against the upper end of the pin to restrict the pin from moving upward.

6. The fiber optic grating sensor overload protection device as described in claim 4, characterized in that, The side of the pin has an elongated through hole arranged parallel to the pin axis. The upper end of the elongated through hole extends to the upper end of the pin to form an optical fiber channel. The optical fiber channel is used to allow the sensing optical fiber circuit to enter when the pin moves upward, so that the pin avoids the sensing optical fiber circuit.

7. The fiber optic grating sensor overload protection device as described in claim 4, characterized in that, The outer casing has a small hole on its side, through which the sensing fiber optic circuit passes.

8. The fiber optic grating sensor overload protection device as described in claim 1, characterized in that, The acquisition end includes a fiber Bragg grating demodulator and a computer.

9. The fiber optic grating sensor overload protection device as described in claim 1, characterized in that, The fiber optic grating sensor has the same length as the sensing fiber loop and is subjected to the same force.

10. The fiber optic grating sensor overload protection device as described in claim 1, characterized in that, Both the fiber optic grating sensor and the sensing fiber optic loop are connected to a protective layer.

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