Smart cable with sensing unit

Abstract

This invention relates to a smart cable containing a sensing unit. The smart cable includes a cable body with a bundle of cable ribs inside, the central cable rib being hollow. It also includes an optical fiber detachably threaded through the hollow rib, to which a sensing unit is connected, and a limiting device for preventing the sensing unit from deviating from its position within the hollow rib. The limiting device includes a sleeve fitted onto the optical fiber, an insulating heat strip fixed to the sleeve, and an elastic component fixed to the sleeve and elastically abutting against the inner wall of the hollow rib. The elastic component includes two rings of elastic ribs located on opposite sides of the insulating heat strip, each ring of elastic ribs being fixed in a divergent manner to the outer periphery of the sleeve. The elastic ribs are made of shape memory material. This invention solves the technical problems in the prior art where the sensing unit in the smart rib with embedded FBG sensor optical fiber cannot be replaced, and where the deformation of the sensing unit and the cable body material is incompatible.

Description

Technical Field

[0001] This invention relates to the field of civil engineering, and more particularly to a smart cable containing a sensing unit. Background Technology

[0002] As a high-strength tension member, cables are widely used in bridge engineering and long-span building structures, and the monitoring of cable stress during operation is receiving increasing attention. In recent years, with the gradual maturation of fiber Bragg grating (FBG) sensing technology, smart cables have been increasingly applied in the engineering field. This involves replacing several steel wires or FRP (fiber reinforced plastic) cables with smart ribs that embed fiber Bragg grating (FBG) sensors. However, due to the inherent fragility of optical fibers, the survival rate of FBGs is very low during the processing of smart ribs and cables, and during installation, easily leading to the failure of the smart cable's self-sensing function. Furthermore, using smart ribs with pre-embedded FBGs requires embedding optical fibers into the ribs according to the cable length before processing, resulting in discontinuous cable production. This significantly restricts the processing efficiency and flexibility of cables. Furthermore, existing technologies using smart cables with retrofitted monitoring elements involve pre-drilling continuous channels within the cable and installing the monitoring elements during the fabrication or construction of the finished cable. While this method ensures the survival rate and replaceability of the monitoring elements, it still presents several problems. For example, the monitoring elements are tightly fixed to both ends of the cable, which cannot guarantee coordinated deformation between the monitoring unit and its cross-section, leading to inaccurate monitoring results. The channels occupy a large cross-sectional area and do not participate in stress distribution, significantly weakening the cable's cross-section. Existing technologies also employ a dragging method to install the filler and optical fiber together into a metal tube, thus addressing the issue of incoordination between the FBG and cable cross-section deformation. However, as the length of the reinforcing bar / cable increases, the frictional resistance between the filler and the inner wall of the metal tube increases dramatically, hindering the proper installation of the optical fiber. This makes the method difficult to implement in practical engineering, and the sensing unit cannot be replaced in this method. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a smart cable containing a sensing unit, which solves the technical problem that the sensing unit in the smart cable with embedded fiber optic grating (FBG) sensor fiber cannot be replaced.

[0004] In a first aspect, the present invention discloses a smart cable containing a sensing unit, comprising a cable body, a bundle of cable ribs within the cable body, wherein the cable rib located at the center is a hollow rib, and further comprising an optical fiber detachably inserted through the hollow rib, wherein a sensing unit is connected to the optical fiber, and a limiting device for preventing the sensing unit from deviating in positioning within the hollow rib, the limiting device comprising a sleeve fitted onto the optical fiber, an insulating heat strip fixed to the sleeve, and an elastic component fixed to the sleeve and used to elastically abut against the inner wall of the hollow rib, the elastic component comprising two rings of elastic ribs located on opposite sides of the insulating heat strip, each ring of elastic ribs being fixed in a divergent manner to the outer periphery of the sleeve, the elastic ribs being made of a memory material.

[0005] A further improvement of the smart cable containing sensing units of the present invention is that the number of sensing units is multiple, the multiple sensing units are arranged at intervals on the optical fiber, and a limiting device is fixed on the opposite outer side of each sensing unit on the optical fiber.

[0006] Secondly, the present invention also provides a method for installing and removing a smart cable containing a sensing unit as described above, comprising the following steps: installing the cable body; inserting a traction wire into the hollow rib, and extending the beginning and end of the traction wire out of the two ends of the hollow rib respectively; using external force to cause plastic deformation of a ring of elastic ribs relatively close to the first end of the optical fiber in the elastic component, and tilting it towards the first end of the optical fiber at a preset angle, so that the end of the elastic rib supports the inner wall of the hollow rib; using external force to cause plastic deformation of a ring of elastic ribs relatively close to the second end of the optical fiber in the elastic component, and tilting it towards the second end of the optical fiber to be attached to the outer periphery of the sleeve;

[0007] Connect the end of the traction wire to the second end of the optical fiber, and then pull the traction wire in the forward direction so that the traction wire drives the optical fiber through the hollow rib until the first end of the optical fiber extends out of the hollow rib; remove the traction wire, and use external temperature excitation to unfold the elastic rib around the outer circumference of the sleeve until it pushes against the inner wall of the hollow rib.

[0008] The intelligent cable containing the sensing unit of the present invention is further improved by including the step of removing the cable body: by using external temperature excitation, the plastic deformation of the elastic ribs in the elastic component that are relatively close to the first end of the optical fiber is eliminated, and the ribs are tilted toward the first end of the optical fiber and attached to the outer periphery of the sleeve, and then the optical fiber is pulled out in the opposite direction.

[0009] The intelligent cable containing sensing units of the present invention is further improved in that the number of sensing units is multiple, and the multiple sensing units are arranged at intervals on the optical fiber. Each sensing unit on the optical fiber is fixed with a limiting device on its opposite outer side. When the elastic tendon is plastically deformed or plastically deformed by means of external force or external temperature excitation, the external force or external temperature excitation is applied to the corresponding elastic tendon in all the limiting devices.

[0010] Compared with existing technologies, the advantages of this invention are positive and significant. This invention utilizes the shape-memory metal material of the metal wire, which can change its shape through external stimulation, solving the technical problem in existing technologies where the sensing units in the smart cable embedded with FBG sensor fibers cannot be replaced. This invention ensures the survival rate of the sensing units within the smart cable; even if a sensing unit is damaged later, it can be easily replaced. The limiting device achieves localized coordination between the sensing unit and the cable body deformation, thereby ensuring monitoring accuracy. Furthermore, it ensures accurate positioning of the subsequently installed sensing unit, improves the processing and production efficiency of the smart cable, and reduces construction difficulty. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0012] Figure 1 This is a longitudinal sectional view of the smart cable containing a sensing unit according to the present invention.

[0013] Figure 2 This is a longitudinal sectional view of the limiting device for the smart cable containing the sensing unit of the present invention, with the optical fiber not installed.

[0014] Figure 3 This is a longitudinal sectional view of the limiting device of the smart cable containing the sensing unit of the present invention in its uninitial state.

[0015] Figure 4 This is a longitudinal sectional view of the limiting device of the smart cable containing a sensing unit of the present invention after an external force has been applied.

[0016] Figure 5 This is an enlarged view of the first group of metal wires of the smart cable containing the sensing unit of the present invention, from the initial state to the state after an external force is applied.

[0017] Figure 6 This is an enlarged view of the second group of metal wires in the smart cable containing the sensing unit of the present invention, showing the transition from the initial state to the state after an external force is applied.

[0018] Figure 7 for Figure 4 Cross-sectional view of the CC line.

[0019] Figure 8 This is a cross-sectional view of the smart cable containing the sensing unit of the present invention during optical fiber installation.

[0020] Figure 9 This is a cross-sectional view of the optical fiber of the smart cable containing the sensing unit of the present invention when it is disassembled.

[0021] In the diagram: 1 hollow rib; 2 sensing unit; 3 limiting device; 301 sleeve; 302 insulating heat strip; 303 a ring of elastic ribs near the first end of the optical fiber; 304 a ring of elastic ribs near the second end of the optical fiber; 4 optical fiber; 5 adhesive; 6 fusion splice. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1-3 As shown, the present invention provides a smart cable containing a sensing unit 2, including a cable body, a bundle of cable ribs inside the cable body, and the cable rib located at the center is a hollow rib 1. It also includes an optical fiber 4 detachably inserted through the hollow rib 1. The sensing unit 2 is connected to the optical fiber 4, and a limiting device 3 for preventing the sensing unit 2 from deviating in the positioning of the hollow rib 1. The limiting device 3 includes a sleeve 301 sleeved on the optical fiber 4, an insulating heat strip 302 fixed to the sleeve 301, and an elastic component fixed to the sleeve 301 and used to elastically abut against the inner wall of the hollow rib 1. The elastic component includes two rings of elastic ribs located on opposite sides of the insulating heat strip 302. Each ring of elastic ribs is fixed in a divergent manner to the outer periphery of the sleeve 301. The elastic ribs are made of memory material.

[0024] The cable body is composed of ordinary FRP ribs and smart ribs. The smart ribs are hollow FRP ribs before the installation of the sensing fiber 4. The smart cable structure of this invention can also be applied to smart ribs. During the fabrication of parallel wire cables and FRP rib cables, the cable body is twisted at a certain angle. The central rib is unaffected by this twisting and remains aligned with the cable axis. Therefore, replacing the central rib with a hollow FRP rib (with the sensing unit 2 installed later) yields the best monitoring effect. In this embodiment, the elastic ribs all include multiple layers of elastic ribs, thereby increasing the friction with the inner wall of the hollow rib 1. Furthermore, these elastic ribs are made of shape memory alloy material.

[0025] Optical fiber 4 includes a grating section with a fixed sensing unit 2 (FBG) and a non-grating section without the sensing unit 2 installed. A limiting device 3 is sleeved at the splice between the grating section and the non-grating section, and is reliably bonded to optical fiber 4 by adhesive 5. Figure 8 As shown, sleeve 301 is bonded to the splice point 6 between the non-grating section fiber and the grating section fiber, reinforcing the splice point 6. The limiting device 3 can change its shape through external temperature excitation, allowing it to have different shapes during installation, use, and disassembly. This shape switching enables smooth installation, use, and disassembly of the fiber 4.

[0026] Preferably, there are multiple sensing units 2, which are spaced apart on the optical fiber 4. Each sensing unit 2 on the optical fiber 4 has a limiting device 3 fixed on its opposite outer side. The smart rib consists of a hollow rib 1 and an optical fiber 4 (i.e., a detachable embedded optical fiber sensor). The optical fiber 4 is located at the center of the hollow rib 1, and each end of the grating has a limiting device 3 supporting it against the inner wall of the hollow rib 1, thus limiting the sensing unit. Installing the optical fiber 4 after the cable is installed ensures the survival rate of the sensing unit 2 in the smart cable / rib; the sensing optical fiber 4 is replaceable, and even if the sensing unit 2 is damaged later, it can be easily replaced; the sensing unit 2 is positioned at the center of the hollow rib 1, ensuring accurate positioning of the subsequent sensing unit 2; the two ends of the sensing unit 2 are bidirectionally locked to the inner wall of the hollow rib 1 by the limiting devices 3. The setting of multiple limiting devices 3 can achieve coordination between the sensing unit 2 and the cable deformation in a local area, thereby ensuring monitoring accuracy.

[0027] On the other hand, such as Figures 3-8 As shown, the present invention also provides a method for installing and removing a smart cable containing a sensing unit as described above, comprising the following steps: installing the cable body; inserting a traction line into the hollow rib 1, and extending the beginning and end of the traction line out of both ends of the hollow rib 1 respectively; as shown... Figure 8 As shown, an external force is used to cause plastic deformation of a ring of elastic ribs 303 relatively close to the first end of the optical fiber in the elastic component, and to tilt towards the first end of the optical fiber 4 at a preset angle so that the end of the elastic rib supports the inner wall of the hollow rib 1; an external force is used to cause plastic deformation of a ring of elastic ribs 304 relatively close to the second end of the optical fiber in the elastic component, and to tilt towards the second end of the optical fiber 4 to be attached to the outer periphery of the sleeve 301; the end of the traction wire is connected to the second end of the optical fiber 4, and then the traction wire is pulled in the forward direction so that the traction wire drives the optical fiber 4 to pass through the hollow rib 1 until the first end of the optical fiber 4 extends out of the hollow rib 1; the traction wire is removed, and the ring of elastic ribs attached to the outer periphery of the sleeve 301 is unfolded by external temperature excitation until it supports the inner wall of the hollow rib 1.

[0028] Preferred, such as Figure 9As shown, the procedure also includes the step of removing the cable body: by using external temperature excitation, the plastic deformation of the elastic rib 303 in the elastic component that is relatively close to the first end of the optical fiber is eliminated, and the rib is tilted toward the first end of the optical fiber and attached to the outer periphery of the sleeve 301, and then the optical fiber 4 is pulled out in the opposite direction.

[0029] Preferably, there are multiple sensing units 2, which are spaced apart on the optical fiber 4. Each sensing unit 2 on the optical fiber 4 is fixed with a limiting device 3 on its opposite outer side. When the elastic tendon is plastically deformed or plastically deformed by external force or external temperature excitation, the external force or external temperature excitation is applied to the corresponding elastic tendon in all the limiting devices 3.

[0030] External temperature excitation can be thermal excitation introduced by electric heating, which is achieved by prefabricating wires and introducing thermal excitation by electric heating when needed.

[0031] The elastic ribs are made of shape memory alloys, such as... Figure 3 As shown, in the undeformed state of the two sets of metal wires, the elastic rib 304 near the second end of the optical fiber forms an angle α2 with the sleeve 301, α2 should be 55°~75° and face the second end A; in the undeformed state, the elastic rib 303 near the first end of the optical fiber is in close contact with the sleeve 301 and faces the first end B.

[0032] Before installing the limit device 3, such as Figure 4 As shown, an external force causes a ring of elastic ribs 303 near the first end of the optical fiber to undergo plastic deformation, so that the ring of elastic ribs 303 near the first end of the optical fiber forms an angle α1 with the axis of the sleeve 301, where α1 is preferably 55°~75° and faces the first end B; at the same time, an external force causes a ring of elastic ribs 304 near the second end of the optical fiber to undergo plastic deformation, so that it is tightly attached to the sleeve 301 and faces the second end A.

[0033] When an external temperature excitation (thermal excitation) is applied to the elastic rib 304 near the second end of the optical fiber, the plastic deformation of the elastic rib 304 near the second end of the optical fiber is eliminated, and the angle α2 between the elastic rib 304 and the axis of the sleeve 301 is restored. Figure 1 As shown.

[0034] When external temperature excitation (thermal excitation) is applied to the elastic rib 303 near the first end of the optical fiber, the plastic deformation of the elastic rib 303 near the first end of the optical fiber is eliminated, and it fits into the sleeve 301. The shape of the limiting device 3 is consistent with that in the undeformed state. Figure 9 As shown.

[0035] The insulating heat strip 302 in the middle of the sleeve 301 ensures that the temperatures of the sleeves 301 at both ends of the variable fiber optic 4 limiting device 3 do not affect each other in a short period of time, thus ensuring individual thermal excitation of the elastic rib on one side. The elastic ribs on both sides of the insulating heat strip 302 face opposite directions, and bidirectional locking can be achieved after installation, thereby achieving coordination between the local deformation of the sensing unit 2 and the cable body, ensuring monitoring accuracy. The specifications and quantity of the sensing unit 2 (grating) and the size of the fiber optic 4 without grating are determined according to the cable length and monitoring scheme. The fiber optic 4 limiting device 3 is inserted into the fiber optic 4 before the non-grating section of the fiber optic 4 is fused with the grating, and then the sensing unit 2 is fused with the fiber optic 4 without grating, connecting several sensing units 2 in series. After the fusion is completed, the limiting device 3 is bonded and fixed to the fiber optic 4 at the fusion joint using adhesive 5. The elastic ribs on both sides of the insulating heat strip 302 of multiple limiting devices 3 face the same direction. In this invention, during the installation and removal of the optical fiber 4, the elastic rib on the side away from the pull-out end is kept at a preset angle. This prevents the sensing unit 2 from contacting the inner wall of the hollow rib 1 during installation and removal, thereby preventing the sensing unit 2 and the optical fiber 4 from being damaged by friction with the inner wall of the hollow rib 1. This ensures the integrity of the sensing unit 2 and the optical fiber 4, further preventing the optical fiber 4 from breaking due to friction with the inner wall of the hollow rib 1, and ensuring that the optical fiber 4 can be completely removed.

[0036] This invention utilizes the shape-memory metal material in the metal wire to change its shape through external stimulation, solving the technical problem in existing technologies where the sensing units in smart cables with embedded FBG sensor fibers cannot be replaced. This invention ensures the survival rate of the sensing units within the smart cable; even if a sensing unit is damaged later, it can be easily replaced. A limiting device achieves localized coordination between the sensing unit and the cable's deformation, thus guaranteeing monitoring accuracy. Furthermore, it ensures accurate positioning of the subsequently installed sensing unit, improving the processing efficiency of the smart cable and reducing construction difficulty.

[0037] All parts not described in this invention are the same as or can be implemented using existing technologies. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, shall still fall within the scope of the present invention.

Claims

1. A smart cable containing a sensing unit, characterized by, The cable body is provided with a bundle of cable wires, and the central cable wire is a hollow wire. The cable body is further provided with an optical fiber which is detachably arranged in the hollow wire. The optical fiber is connected with a sensing unit and a limiting device for preventing the sensing unit from being deviated in the hollow wire. The limiting device comprises a sleeve which is sleeved on the optical fiber, an insulation and heat insulation band which is fixed on the sleeve, and an elastic assembly which is fixed on the sleeve and used for elastically abutting against the inner wall of the hollow wire. The elastic assembly comprises two turns of elastic wires which are respectively arranged on the opposite sides of the insulation and heat insulation band. Each turn of the elastic wire is fixed on the outer periphery of the sleeve in a diverging manner. The elastic wire is made of a memory material. The method for installing and removing the optical fiber in the intelligent cable with sensing units comprises the following steps: installing the cable body; arranging a traction wire in the hollow wire, and extending the starting end and the terminal end of the traction wire out of the two ends of the hollow wire; plastically deforming the turn of the elastic assembly which is relatively close to the first end of the optical fiber by external force, and tilting the turn of the elastic assembly towards the first end of the optical fiber to a preset angle so that the end of the turn of the elastic assembly abuts against the inner wall of the hollow wire; plastically deforming the turn of the elastic assembly which is relatively close to the second end of the optical fiber by external force, and tilting the turn of the elastic assembly towards the second end of the optical fiber to abut against the outer periphery of the sleeve; connecting the terminal end of the traction wire with the second end of the optical fiber, and then positively pulling the traction wire so that the traction wire drives the optical fiber to be arranged in the hollow wire until the first end of the optical fiber extends out of the hollow wire; 2. The smart cable containing a sensing unit according to claim 1, wherein, removing the traction wire, and expanding the turn of the elastic wire which abuts against the outer periphery of the sleeve by external temperature excitation until the turn of the elastic wire abuts against the inner wall of the hollow wire.

3. The smart cable containing a sensing unit according to claim 1, wherein, The number of the sensing units is multiple. The multiple sensing units are arranged on the optical fiber in a spaced manner. The limiting device is fixed on the opposite outer sides of each sensing unit on the optical fiber. The method for installing and removing the optical fiber in the intelligent cable with sensing units further comprises the following step of removing the cable body:

4. The smart cable containing a sensing unit according to claim 1, wherein, eliminating the plastic deformation of the turn of the elastic assembly which is relatively close to the first end of the optical fiber by external temperature excitation, and tilting the turn of the elastic assembly towards the first end of the optical fiber to abut against the outer periphery of the sleeve, and then reversely pulling out the optical fiber. The number of the sensing units is multiple. The multiple sensing units are arranged on the optical fiber in a spaced manner. The limiting device is fixed on the opposite outer sides of each sensing unit on the optical fiber. When the elastic wire is plastically deformed or the plastic deformation of the elastic wire is eliminated by external force or external temperature excitation, the external force or the external temperature excitation is applied to the corresponding turn of the elastic wire in all the limiting devices.

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