Carbon fiber composite material combined mooring cable system for offshore floating structure and self-monitoring method

Abstract

The invention discloses a carbon fiber composite material combined mooring cable system for an offshore floating structure and a self-monitoring method. The mooring cable system comprises three sections of mooring cables made of different materials, namely a first mooring cable located on the upper section, a carbon fiber composite mooring cable located on the middle section and a second mooring cable located on the lower section, and all the sections of the cable system are connected through mechanical connecting structures. The first mooring cable is led to the floating platform through the cable fair lead and wound on the winch, the tensiometer is installed between the first mooring cable and the carbon fiber composite mooring cable, displacement meters are installed in anchorage devices at the two ends of the carbon fiber composite mooring cable, the second mooring cable is provided with a stress meter, and the tail end of the second mooring cable is connected to the gravity type anchoring foundation. The application of the carbon fiber composite material in the ocean engineering mooring cable is combined with advanced sensing technologies such as optical fiber sensing, the intelligent level of the cable is improved, and the reliability of a cable system and the accuracy of damage detection are ensured.

Description

Technical Field

[0001] The present invention relates to the field of marine engineering technology, and in particular to a carbon fiber composite material combined mooring cable system for offshore floating structures and a self-monitoring method. Background Art

[0002] Offshore floating structures, such as floating wind power platforms and floating docks, usually rely on mooring systems to maintain stability and safety. As a key component of these structures, mooring cables undertake the important task of supporting and fixing the structure. Traditional mooring cables are mostly made of metal materials or synthetic fiber materials, such as steel anchor chains, steel wire ropes, and polyethylene cables. However, with the advancement of the construction of large-scale deep-sea platforms with a capacity of more than 1,000 tons, mooring cables made of traditional metal materials will not be able to be used, and the high creep of synthetic fiber cables also makes them unable to be used for a long time. Therefore, it is necessary to apply new materials in mooring cables.

[0003] Carbon fiber composite materials have the advantages of light weight, good corrosion resistance, high strength and high stiffness. With the improvement of carbon fiber composite materials' performance and the reduction of production costs, their application in marine engineering has gradually increased, and they have also become an ideal choice for mooring cable materials. In the actual service of mooring cables, the cable body in the air-seawater interface area (splash zone) is most seriously corroded and aged due to repeated scouring by seawater. Compared with traditional mooring cable materials, carbon fiber composite materials can be used as the best choice for cable splash zone materials due to their performance advantages. At the same time, due to the requirements of floating platforms for the coiling and winding of mooring cables, and the requirements of seabed anchoring for cable gravity, traditional polymer synthetic fiber cables and steel anchor chains can also be used. Carbon fiber composite materials and traditional mooring cables are applied in appropriate sections and combined to form a new type of mooring cable system, giving full play to the performance advantages of each material. With the advancement of major marine engineering construction, this new type of mooring cable system will also face huge application needs. The mechanical properties of the carbon fiber mooring cable system are completely different from those of traditional mooring cables. The overall structural form needs to be redesigned, and it has higher complexity and challenges. In view of the actual demand for carbon fiber composite mooring cables, the overall structure of the carbon fiber composite mooring cable system is specially designed, and a new type of mooring cable with light weight, long life and low creep is proposed.

[0004] At the same time, the understanding of the service performance of this new type of carbon fiber composite mooring cable is still in a blank stage, and relevant non-destructive testing and monitoring methods are needed to evaluate its performance in the marine environment. At present, there are several non-destructive testing technologies for cable structures:

[0005] Visual inspection and manual inspection, visual inspection relies on human eye observation, while manual inspection evaluates the health of the structure through tapping or auditory observation. However, these methods are susceptible to subjective judgment and operator experience, resulting in inconsistent results. They cannot provide precise quantitative data, only qualitative observations, and have limited effectiveness in detecting hidden or internal problems, such as deep cracks or hidden corrosion.

[0006] Structural dynamic response monitoring,Structural dynamic response monitoring uses accelerometers or sensors to measure the vibration response of the structure under external excitation. Although this method can reflect the overall vibration characteristics of the structure, it requires complex mathematical models and data analysis techniques to infer the health status of the structure. The complexity of data analysis and the accuracy of the model are its main challenges, and it is difficult to provide immediate feedback.

[0007] Strain measurement technology, sensors such as strain gauges or strain gauges are installed on the surface of the structure to measure the strain state under different working conditions. However, the installation position of the strain gauge is difficult to change once it is determined, and it is greatly affected by complex environmental conditions, such as high temperature or the presence of chemicals. In addition, they can only measure surface strain and have limited detection capabilities for deep or hidden structural problems.

[0008] Acoustic emission testing relies on monitoring the sound produced by the structure under load or stress to identify internal defects or deformations. However, this method is sensitive to environmental noise and interference, which may lead to false alarms or misdiagnosis. Its positioning accuracy is limited and it can usually only roughly determine the location of the problem. It is difficult to provide accurate positioning to the centimeter level, especially for complex or multi-layer structures.

[0009] Electromagnetic detection technology uses electromagnetic waves such as ultrasound or electromagnetic induction to detect defects or material state changes inside the structure. However, its application is limited by the structural materials and geometry, and requires high materials with specific electromagnetic responsiveness. The penetration and propagation capabilities of electromagnetic waves may be limited, making it difficult to fully detect all parts of a complex structure.

[0010] The above-mentioned non-destructive testing and monitoring methods still have their value in certain scenarios, but their limitations also determine that they are not suitable for the detection and monitoring of carbon fiber composite mooring cables in marine environments. In comparison, fiber optic sensing technology has multiple advantages in the non-destructive testing of carbon fiber mooring cables. First, it can monitor the key parameters of the mooring cable such as tension and strain in real time, and it has high sensitivity and can detect small changes and fluctuations, including structural deformation and small changes in stress distribution. This high sensitivity enables fiber optic sensing technology to detect potential fatigue cracks, damage or other structural problems at an early stage, which helps to detect potential structural problems early. In addition, fiber optic sensing technology has remote monitoring capabilities. Sensors can be distributed over long distances along the entire length of the mooring cable and can realize remote data transmission and monitoring. This remote monitoring capability not only reduces the direct intervention of operators, but also reduces work risks, especially in harsh or inaccessible marine environments.

[0011] Overall, fiber optic sensing technology has shown broad application prospects and significant technical advantages in the non-destructive testing of carbon fiber mooring cables. Its high flexibility and adaptability enable it to be customized and adjusted for carbon fiber mooring cables of different types and sizes to meet the actual needs in complex and changing marine environments. By real-time monitoring of key parameters of mooring cables, such as tension and strain, fiber optic sensors can provide a continuous data stream to help maintenance personnel detect potential structural problems early, thereby reducing the risk of emergencies and optimizing maintenance plans.

[0012] At present, there is no non-destructive testing and monitoring method specifically for carbon fiber composite mooring cables. Moreover, it is technically difficult to comprehensively monitor the strain, stress and anchor slip of mooring cables. Under the actual needs of carbon fiber composite mooring cables, based on advanced sensing technology and combined with structural system design, the detection and monitoring system is used to comprehensively monitor the stress, strain and anchor slip of carbon fiber composite mooring cables in service, evaluate their mechanical properties and anchoring performance, and thus test and verify the applicability of carbon fiber composite mooring cables, a new type of mooring form. Summary of the invention

[0013] In response to the above technical problems, the present invention proposes a carbon fiber mooring cable system for offshore floating structures. The cable system combines optical fiber sensing technology to monitor the strain of the cable in real time and a vibrating wire stress gauge anchor chain ring to monitor the stress condition of the anchor chain segment in real time, thereby realizing non-destructive detection of damage to the carbon fiber mooring cable system.

[0014] In order to achieve the above technical objectives, the present invention adopts the following technical means:

[0015] A carbon fiber composite composite mooring cable system for an offshore floating structure, the mooring cable system comprises three sections of mooring cables made of different materials, namely a first mooring cable located in an upper section, a carbon fiber composite mooring cable located in a middle section, and a second mooring cable located in a lower section. The sections of the cable system are connected by a mechanical connection structure, wherein:

[0016] The first mooring cable is led onto the floating platform through a fairlead and wound onto a winch, a tension meter is installed between the first mooring cable and the carbon fiber composite mooring cable, displacement meters are installed in the anchors at both ends of the carbon fiber composite mooring cable, a strain meter is installed on the second mooring cable, and the end of the second mooring cable is connected to a gravity anchor foundation;

[0017] The data line of the displacement meter and the data line of the strain meter naturally extend upward to the platform;

[0018] Some of the carbon fiber composite rods in the carbon fiber composite mooring cable are embedded with optical fibers, and the carbon fiber composite rods embedded with optical fibers form intelligent carbon fiber composite rods. The optical fibers and the tension meter data line are led out from the end of the carbon fiber composite mooring cable and indexed above the water surface along the first mooring cable. The end of the optical fiber is connected to a related demodulator device, and the end of the tension meter data line is connected to a related data acquisition device.

[0019] The carbon fiber composite mooring cable comprises: a carbon fiber composite rod, a high-strength material belt and a protective cover, wherein a plurality of carbon fiber composite rods are arranged in parallel and twisted with a small torsion angle, the carbon fiber composite rod group is wrapped with a high-strength material belt, and two inner and outer protective covers are added on the outside to protect the internal structure, and the optical fiber is implanted in some of the carbon fiber composite rods in the carbon fiber composite rod group.

[0020] The number of carbon fiber composite rods with embedded optical fibers in the carbon fiber composite mooring cable is not less than one third of the total number of carbon fiber composite rods.

[0021] The first mooring cable is a polymer synthetic fiber cable,

[0022] The upper end of the carbon fiber composite mooring cable is anchored into the first anchor, the outer thread processed on the outer cylinder of the first anchor is screwed with the inner thread of the inner hole of the first lifting ear, a space is left between the bottom plate of the first anchor and the bottom plate of the first lifting ear, the carbon fiber composite rod of the carbon fiber composite mooring cable passes through the bottom plate of the first anchor, a first displacement meter is installed on a plurality of carbon fiber composite rods and connected to the first positioning screw rod, the optical fiber implanted in the carbon fiber composite rod is led out from the end of the carbon fiber composite rod and then connected to the armored optical fiber in the space between the bottom plate of the anchor and the bottom plate of the first lifting ear, one armored optical fiber is connected to multiple fiber cores, a hole is opened on the bottom plate of the first lifting ear, the armored optical fiber in the bottom plate of the first lifting ear is led out of the hole to the first lifting ear, and waterproof glue is injected into the hole;

[0023] The armored optical fiber and the tensiometer data line are arranged in parallel and protected by a casing. They are attached to the polymer synthetic fiber cable and led onto the floating platform together.

[0024] The upper end of the first lifting ear is connected to the insertion end of the first shackle, the upper part of the first shackle is connected to the second shackle, the second shackle is connected to the tension meter, the upper end of the tension meter is connected to the third shackle, and the upper part of the third shackle is connected to the chicken heart eye ring and the polymer synthetic fiber cable.

[0025] The second mooring cable is a steel anchor chain, the lower end of the carbon fiber composite mooring cable is anchored into the second anchor, the outer cylindrical surface of the second anchor is processed with an external thread which is screwed into the inner thread of the inner hole of the second lifting ear, a space is left between the bottom plate of the second anchor and the bottom plate of the second lifting ear, the carbon fiber composite rod of the carbon fiber composite mooring cable passes through the bottom plate of the second anchor, and a plurality of carbon fiber composite rods are selected from the carbon fiber composite rods extending out of the bottom plate of the anchor, the center points of the plurality of carbon fiber composite rods are equidistant from the center of the anchor, and the center points of the plurality of carbon fiber composite rods are arranged symmetrically with respect to the center of the anchor;

[0026] Among the plurality of carbon fiber composite rods, the end of each carbon fiber composite rod is connected to a probe of the displacement meter through a connecting cap;

[0027] Two connecting metal sheets, one end of which is symmetrically clamped on both sides of the displacement meter and fixedly connected to the displacement meter through a first fixing bolt, and the other end of which is symmetrically clamped on both sides of the positioning screw rod and fixedly connected to the positioning screw rod through a second fixing bolt;

[0028] When the carbon fiber composite rod in the anchor slips relative to the anchor, the connecting cap moves axially with the carbon fiber composite rod, driving the probe of the displacement meter to move axially. The average displacement measured by several displacement meters is the anchor slip amount.

[0029] The lower end of the second lifting ear is connected to the insertion end of the fourth shackle, and the lower end of the fourth shackle is connected to the steel anchor chain segment, wherein the steel anchor chain segment is provided with an anchor chain ring, and two stress gauges are welded on the anchor ring; the terminal end of the steel anchor chain segment is fixed on a gravity anchor foundation, and the foundation adopts a square prism form with a concave bottom.

[0030] Three carbon fiber composite rods are selected from the carbon fiber composite rods extending out of the anchor bottom plate, the center points of the three carbon fiber composite rods are equidistant from the center of the anchor, and the lines connecting the center points of the three carbon fiber composite rods and the center of the anchor form 120° with each other.

[0031] The strain gauge is a vibrating-wire strain gauge. A connecting anchor ring in the anchor chain ring is cut into two half anchor rings. The vibrating-wire strain gauge is connected between the two half anchor rings. The data line of the vibrating-wire strain gauge is led outward from the adapter and is provided with a protective cover.

[0032] The displacement meter is an underwater micro displacement meter.

[0033] The present invention further discloses a self-monitoring method for the carbon fiber composite combined mooring cable system for an offshore floating structure.

[0034] The real-time strain data of the smart carbon fiber composite rod inside the carbon fiber composite mooring cable is obtained through the optical fiber implanted in the carbon fiber composite mooring cable;

[0035] The stress data measured by the tensiometer is used to obtain the distribution of the strain difference Δε along the length direction of the cable under a certain stress difference Δσ. For an intact composite rod, the distribution of the strain difference Δε is a horizontal straight line. If a sudden jump occurs in the distribution diagram, the section with the sudden jump is the damaged section.

[0036] The stiffness distribution of the composite rod is calculated by E = Δσ / Δε. The damage stiffness value Cd of the damaged section is equal to the initial stiffness E0 minus the stiffness value Ed of the damaged section, that is, Cd = E0-Ed;

[0037] Finally, the damage location and size are determined according to the anchor slip detected by the displacement meter inside the carbon fiber composite mooring cable, and the damage state of the entire carbon fiber composite mooring cable is judged.

[0038] The above technical solution of the present invention has the following advantages compared with the prior art:

[0039] The carbon fiber composite combined mooring cable system for offshore floating structures described in the present invention innovatively applies carbon fiber composite materials to mooring cables, and cleverly combines and connects with other traditional mooring cable materials. In addition, an anchor tension meter is installed in the upper section, an underwater micro displacement meter is installed in the anchor, and a vibrating wire stress meter is installed in the anchor chain section to monitor the tension, strain and damage of the cable in real time. While improving the strength and corrosion resistance of the mooring cable, it also gives full play to the role and advantages of traditional mooring cable materials, making the overall structure of the formed new mooring cable system more reliable.

[0040] The carbon fiber composite combined mooring cable system for offshore floating structures described in the present invention combines carbon fiber composite materials with advanced optical fiber sensing technology, and efficiently and accurately detects and monitors the damage of the carbon fiber composite mooring cable by analyzing and processing the measured strain data of the optical fiber implanted in the carbon fiber composite mooring cable. The real-time data of the cable is obtained by using a tensiometer, a displacement meter and a vibrating-wire stress gauge, thereby giving the mooring cable system the ability of real-time monitoring and improving the intelligence level of the mooring cable system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall structure of the intelligent carbon fiber composite mooring cable system of the present invention;

[0042] Among them, 1: floating platform main control room, 2: winch, 3: data cable and transmission line, 4: cable rack, 5: cable guide wheel, 6: polymer synthetic fiber cable, 7: tension meter data cable, 8: displacement meter transmission line, 9: tension meter, 10: armored optical fiber and tension meter data cable, 11-1: first lifting lug, 11-2: second lifting lug, 12: anchor, 13: strain meter transmission line, 14: ring for fixing transmission line, 15: carbon fiber composite mooring cable, 16: vibrating wire strain meter, 17: steel anchor chain, 18: gravity anchor.

[0043] Figure 2 It is a three-view drawing of the connection area of ​​the carbon fiber composite mooring cable and the polymer synthetic fiber cable of the present invention;

[0044] Among them, 19-1: first shackle, 19-2: second shackle, 19-3: third shackle, 20: chicken eye ring;

[0045] Figure 3 is a longitudinal section view of the anchor of the present invention;

[0046] Among them, 12-1: displacement meter data line, 12-2: displacement meter, 12-3: connection cap, 12-4: connection metal sheet, 12-5: anchor bottom plate, 12-6: positioning screw rod, 12-7: wire dividing plate, 12-8: anchor cup, 12-9: nut, 12-10: second fixing bolt of metal sheet, 12-11: bolt hole, 12-12: epoxy iron sand filling;

[0047] Figure 4 is an end view of the anchor of the present invention;

[0048] Among them, 12-13: opening of the carbon fiber composite rod of the bottom plate; 12-14: the first fixing bolt of the metal sheet;

[0049] Figure 5 It is a cross-sectional schematic diagram of an optical fiber implanted in a carbon fiber composite rod of the present invention;

[0050] Among them, 15-1: outer sheath, 15-2: inner sheath, 15-3: high-strength material belt, 15-4: carbon fiber composite rod without optical fiber implanted, 15-5: intelligent carbon fiber composite rod;

[0051] Figure 6 It is a schematic diagram of the end faces of the optical fibers and displacement meter data lines leading out of the lifting ears at the upper and lower ends of the carbon fiber cable segment of the present invention;

[0052] Among them, 11-1: first lifting ear, 11-1-1: armored optical fiber lead-out port, 11-3-1: first lifting ear bottom plate, 11-1-2: displacement meter data line lead-out port; 11-2: second lifting ear, 11-3-2: second lifting ear bottom plate;

[0053] Figure 7 It is a schematic diagram of the arrangement of the armored optical fiber and the tensiometer data line of the present invention;

[0054] Among them, 6-2: casing, 15-5-1: armored optical fiber, 15-5-2: optical fiber core, 6-1: flexible material filling;

[0055] Figure 8 is a schematic diagram of a custom vibrating wire stress gauge anchor ring of the present invention;

[0056] Among them, 16-1: half anchor ring, 16-2: vibrating wire strain gauge, 16-3: strain gauge data line adapter, 16-4: data line with protective cover;

[0057] Fig. 9 It is a schematic diagram of the connection area of ​​the carbon fiber composite mooring cable and the steel anchor chain of the present invention;

[0058] Among them, 11-2: second lifting lug, 19-4: fourth shackle;

[0059] Fig.10 This is a graph of strain difference distribution data of a composite rod measured by an optical fiber according to the present invention;

[0060] Fig.11 This is a data diagram of the stiffness distribution of the optical fiber composite rod measured by the present invention. DETAILED DESCRIPTION

[0061] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0062] Reference Figure 1 As shown, the present invention provides an intelligent carbon fiber composite mooring cable system, characterized in that:

[0063] The overall cable system consists of three sections of mooring cables made of different materials. The upper section is a polymer synthetic fiber cable 6, the middle section is a carbon fiber composite cable 15 with embedded optical fiber, and the lower section is a steel anchor chain 17 with a vibrating wire stress gauge 16.

[0064] Each section of the cable system is connected by a mechanical connector and a mechanical connector with tension detection. Among them, a ship anchor chain tension meter 9 is installed between the carbon fiber composite mooring cable 15 and the polymer synthetic fiber cable 6. A displacement meter 12-2 is installed between the first anchor at the upper end and the second anchor at the lower end and the first and second lifting ears respectively.

[0065] The end of the lower steel anchor chain 17 is connected to a gravity concrete anchor foundation 18 .

[0066] The optical fiber embedded in the carbon fiber composite mooring cable is led out from the end of the lifting ear and is indexed onto the floating platform along the mooring cable together with the tension meter data line 7. The end of the armored optical fiber 15-5-1 is connected to the relevant demodulator device, and the end of the tension meter data line 7 is connected to the relevant data acquisition instrument equipment.

[0067] Specifically, both ends of the carbon fiber composite mooring cable 15 are anchored into the anchor 12, and the outer cylindrical surface of the anchor 12 is processed with an external thread that matches the internal thread of the inner hole of the lifting lug 11, that is, the anchor 12 and the lifting lug 11 are connected by threads.

[0068] The carbon fiber composite mooring rope 15 and the steel anchor chain 17 are connected by mechanical connectors, such as Fig. 9 The customized anchor chain ring is composed of two cut-off half anchor rings 16-1 and a vibrating wire strain gauge 16-2 connecting the two half anchor rings. The strain gauge is led to the outside by the strain gauge data line adapter 16-3 and is provided with a protective cover 16-4. Figure 8 shown.

[0069] like Fig. 9 As shown, a hole is opened on the second lifting ear 11 - 2 , one end of the fourth shackle 19 - 4 is inserted into the hole of the second lifting ear 11 - 2 , and the other end of the fourth shackle 19 - 4 is directly inserted into the anchor chain ring of the steel anchor chain 17 .

[0070] like Figure 2 As shown, the carbon fiber composite mooring cable 15 and the polymer synthetic fiber cable 6 are connected by a mechanical connector with tension detection. A hole is opened on the first lifting lug 11-1, and one end of the first shackle 19-1 is inserted into the hole of the first lifting lug 11-1. The upper part of the first shackle 19-1 is connected to the second shackle 19-2, and the second shackle 19-2 is connected to the tension meter 9. The upper end of the tension meter 9 is further connected to a third shackle 19-3, and the upper part of the third shackle 19-3 is connected to a chicken heart eye ring 20, and the polymer synthetic fiber cable 6 is tied to the chicken heart eye ring 20.

[0071] Selecting a plurality of carbon fiber composite rods from the carbon fiber composite rods extending out of the anchor bottom plate, wherein the center points of the plurality of carbon fiber composite rods are equidistant from the center of the anchor, and the center points of the plurality of carbon fiber composite rods are arranged in a central symmetric manner with respect to the center of the anchor;

[0072] Among the selected plurality of carbon fiber composite rods, the end of each carbon fiber composite rod is connected to a probe of the displacement meter through a connecting cap 12-3;

[0073] Two connecting metal sheets 12-4, one end of which is symmetrically clamped on both sides of the displacement meter and fixedly connected to the displacement meter through a first fixing bolt, and the other end of which is symmetrically clamped on both sides of the positioning screw rod 12-6 and fixedly connected to the positioning screw rod 12-6 through a second fixing bolt;

[0074] When the carbon fiber composite rod in the anchorage slips relative to the anchorage, the connection cap 12-3 moves axially with the carbon fiber composite rod, driving the probe of the displacement meter 12-2 to move axially, and converting the anchorage slippage into the displacement value measured by the displacement meter 12-2. The real-time displacement measurement of the three displacement meters is averaged to obtain the anchorage slippage.

[0075] Specifically, the distances between the center points of the three carbon fiber composite rods on which the connection cap 12-3 is installed and the center of the anchor 12 should be approximately equal, and the lines connecting the center points of the three rods and the center of the anchor 12 are 120° to each other. Figure 4 shown.

[0076] Specifically, the optical fiber implanted in the carbon fiber composite mooring cable 15 is led out from the end of the composite rod and connected to the armored optical fiber 15-5-1 in the space between the end of the anchor 12 and the bottom plate of the lug. One armored optical fiber 15-5-1 can be connected to multiple optical fiber cores 15-5-2. At the same time, a displacement meter 12-2 is installed between the screw rod 12-6 on the anchor and the carbon fiber composite rod, which is connected by a metal sheet 12-4 and a bolt 12-14 to bundle the displacement meter data line in three parts.

[0077] The first hanging ear bottom plate 11-3-1 has a hole, such as Figure 6 As shown, the armored optical fiber 15-5-1 in the first lifting ear 11-1 and the bundled displacement meter data line 8 are led out from the armored optical fiber lead-out port 11-1-1 and the displacement meter data line lead-out port 11-1-2 respectively, and waterproof glue is injected into the hole to prevent water from entering the first lifting ear 11-1 and the first anchor.

[0078] Specifically, the armored optical fiber 15-5-1 and the tensiometer data line 7 are arranged in parallel and are fully wrapped and protected by the casing 6-2. Figure 7 shown.

[0079] Specifically, the carbon fiber composite mooring rope 15 is composed of an ordinary carbon fiber composite rod 15-4, an intelligent carbon fiber composite rod 15-5, a high-strength material belt 15-3, an inner sheath 15-2 and an outer sheath 15-1. Figure 5 As shown. A plurality of ordinary carbon fiber composite rods 15-4 and intelligent carbon fiber composite rods 15-5 are arranged in parallel and twisted at a small torsion angle. The carbon fiber composite rod group is wrapped with a high-strength material belt 15-3, and two layers of sheaths, an inner sheath 15-2 and an outer sheath 15-1, are added on the outside to protect the internal structure. A distributed optical fiber sensor is implanted in the intelligent carbon fiber composite rod 15-5, and the optical fiber is led out from the end of the composite rod. The implanted optical fiber sensor can be used in conjunction with a demodulator to obtain cable strain data.

[0080] Specifically, the number of the smart carbon fiber composite rods 15-5 with embedded optical fibers in the carbon fiber composite mooring cable 15 should not be less than one third of the total number of composite rods.

[0081] The present invention provides a nondestructive testing method for a carbon fiber mooring cable system of an offshore floating structure, and obtains the real-time strain data of the intelligent carbon fiber composite rod 15-5 inside the carbon fiber composite mooring cable 15 through the optical fiber implanted in the carbon fiber composite mooring cable 15. By combining the actual stress data measured by the tensiometer 9, the distribution of the strain difference Δε along the length direction of the cable under a certain stress difference Δσ is obtained. For an intact composite rod, the distribution of the strain difference Δε is a horizontal straight line. If a jump occurs in the distribution diagram, the section with the jump is the damaged section. The stiffness distribution of the composite rod can be calculated by E=Δσ / Δε, and the damaged stiffness value Cd of the damaged section is equal to the initial stiffness E0 minus the stiffness value Ed of the damaged section, that is, Cd=E0-Ed. Finally, the damage state of the entire carbon fiber composite mooring cable 15 is judged according to the damage position and size of the intelligent carbon fiber composite rod 15-5 in the cable.

[0082] The nondestructive testing method for the carbon fiber mooring cable system of an offshore floating structure of the present invention will be described in detail below in conjunction with specific embodiments.

[0083] Embodiment 1

[0084] Using intelligent carbon fiber composite mooring cable system on a floating structure in a certain sea area, such as Figure 1 As shown, the upper polymer synthetic fiber cable 6 is extended from the upper floating structure into the water, and the eyelet 20 at the lower end is connected to the first lifting lug 11-1 through a mechanical connector with tension detection. The first lifting lug 11-1 is connected to the first anchor through a thread. One end of the carbon fiber composite cable 15 is anchored into the first anchor, and the other end is anchored into the second anchor. The second anchor is connected to the second lifting lug 11-2 through a thread. The second lifting lug 11-2 is connected to the anchor chain 17 with a vibrating wire strain gauge 16 through a mechanical connector. The anchor chain 17 is connected to the gravity anchor foundation 18. The above assembling completes the entire mooring system.

[0085] Among them, Figure 2 As shown, in the mechanical connector with tension detection, both ends of the tension meter 9 are connected to shackles respectively, one end of the tension meter 9 is sleeved on the chicken eye ring 20 through the third shackle 19-3, and the other end is connected to the first shackle 19-1 through the second shackle 19-2, and the first shackle 19-1 is sleeved in the hole of the first lifting ear 11-1. Fig. 9 As shown, in the mechanical connector connected to the lower anchor chain, the rear end of the second anchor is screwed into the second lifting ear 11-2, the fourth shackle 19-4 is inserted into the hole of the second lifting ear 11-2, and then the fourth shackle is inserted into an anchor chain ring at the end of the steel anchor chain 17.

[0086] Embodiment 2

[0087] Seven optical fibers are embedded in the carbon fiber composite mooring cable 15 and led out from the end of the composite rod. A four-core armored optical fiber 15-5-1 is connected in the gap between the end of the first anchor and the first lifting ear bottom plate. One optical fiber led out from the composite rod can be connected to one optical fiber core 15-5-2 in the armored optical fiber 15-5-1, and two armored optical fibers 15-5-1 are used in total. Figure 6 As shown, two armored optical fibers 15-5-1 are respectively led out from the armored optical fiber lead-out port 11-1-1 opened on the first lifting ear bottom plate 11-3-1, and the displacement meter data line 12-1 is led out from the displacement meter data line lead-out port 11-1-2, and waterproof glue is injected into the hole to prevent water from entering the first lifting ear 11-1 and the first anchor.

[0088] The armored optical fiber 15-5-1 and the tensiometer data line 7 drawn from the first lifting lug 11-1 are arranged in parallel and drawn onto the floating platform along the polymer synthetic fiber cable 6. The armored optical fiber 15-5-1 and the tensiometer data line 7 are wrapped and protected together with the casing 6-2. Figure 7 After the armored optical fiber 15-5-1 and the tension meter data line 7 are led to the platform, the end of the armored optical fiber 15-5-1 is connected to the relevant demodulator device, and the end of the tension meter data line 7 is connected to the relevant data acquisition device.

[0089] Embodiment 3

[0090] Three carbon fiber composite rods are selected from the carbon fiber composite rods extending out of the anchor bottom plate, the center points of the three carbon fiber composite rods are equidistant from the center of the anchor 12, and the lines connecting the center points of the three rods and the center of the anchor 12 are 120° to each other.

[0091] Among the three carbon fiber composite rods, the end of each carbon fiber composite rod is connected to a probe of the displacement meter through a connecting cap 12-3;

[0092] Two connecting metal sheets 12-4, one end of which is symmetrically clamped on both sides of the displacement meter and fixedly connected to the displacement meter through a first fixing bolt 12-14, and the other end of which is symmetrically clamped on both sides of the positioning screw rod 12-6 and fixedly connected to the positioning screw rod 12-6 through a second fixing bolt 12-10;

[0093] When the carbon fiber composite rod in the anchor slips relative to the anchor, the connecting cap 12-3 moves axially with the carbon fiber composite rod, driving the probe of the displacement meter to move axially. The average displacement measured by the three displacement meters is the anchor slip amount.

[0094] Embodiment 4

[0095] like Fig. 9 As shown, the carbon fiber composite mooring cable 15 and the steel anchor chain 17 are connected by a mechanical connector, and the strain gauge is a vibrating wire strain gauge.

[0096] like Figure 8 As shown, one connecting anchor ring in the anchor chain ring is cut into two half anchor rings 16-1, and the vibrating wire strain gauge 16-2 is connected between the two half anchor rings 16-1. The data line of the vibrating wire strain gauge 16-2 is led to the outside from the adapter and is provided with a protective cover 16-4.

[0097] Embodiment 5

[0098] The carbon fiber composite cable 15 is formed by 37 carbon fiber composite rods arranged in parallel and twisted at a small angle. Figure 4 As shown. The elastic modulus of the carbon fiber composite rod is E0 = 180GPa. The carbon fiber composite rod group is wrapped with a high-strength material belt 15-3, and an inner sheath 15-2 and an outer sheath 15-1 are added to the outside to protect the internal structure. Distributed optical fiber sensors are implanted in seven of the carbon fiber composite rods to form #1-#7 intelligent carbon fiber composite rods 15-5. The remaining 29 carbon fiber composite rods are ordinary carbon fiber composite rods 15-4.

[0099] Real-time strain data is obtained through the optical fiber implanted in the #1-#7 intelligent carbon fiber composite rod 15-5. By combining the measured stress data of the tensiometer 9, the distribution of the strain difference Δε along the length direction within the length of 0-500mm in the #1-#7 intelligent carbon fiber composite rod 15-5 is obtained when Δσ=100MPa, as shown in FIG. Fig.10 As shown in the figure, the section with a sudden jump in the strain difference Δε distribution diagram is the damaged section. The damage is located according to the position of the strain difference mutation point. The position of the damaged section of the #1-#7 smart carbon fiber composite rod 15-5 is shown in Table 1.

[0100] Table 1 Damage section location of smart carbon fiber composite rod (unit: mm)

[0101]

[0102]

[0103] The stiffness distribution of the #1-#7 intelligent carbon fiber composite rod 15-5 is calculated by E=Δσ / Δε, Δσ=100MPa, and the distribution of the stiffness of the #1-#7 intelligent carbon fiber composite rod 15-5 within the length of 0-500mm along the length direction is as follows: Fig.11 The damage stiffness value C of the damaged section d Equal to the initial stiffness E0 minus the stiffness value E of the damaged section d , that is, C d =E0-E d , the damage stiffness value of the damaged section 15-5 of the #1-#7 smart carbon fiber composite rod is shown in Table 2.

[0104] Table 2 Damage stiffness of damaged section of smart carbon fiber composite rod (unit: GPa)

[0105]

[0106]

[0107] According to the damage stiffness values ​​of the #1-#7 intelligent carbon fiber composite rods 15-5, it can be judged that the carbon fiber composite mooring cable 15 is within the range of 0-500 mm, and the area where the #2-#5 intelligent carbon fiber composite rods 15-5 are located is more seriously damaged.

[0108] The present invention innovatively applies carbon fiber composite materials to mooring cables, and cleverly combines and connects them with other traditional mooring cable materials, giving full play to the excellent performance of each section of the material, making the overall structure of the formed new mooring cable system more reliable. In addition, a tension meter is installed in the upper section, an optical fiber sensor is buried in the carbon fiber composite rod, an underwater micro displacement meter is installed in the anchor, and a vibrating wire stress meter is installed in the anchor chain section to monitor the tension, strain, anchor slip and other parameters of the cable in real time, giving the mooring cable system the ability to monitor damage in real time, and improving the intelligence level of the mooring cable system.

[0109] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A carbon fiber composite combined mooring cable system for an offshore floating structure, characterized in that: The mooring cable system includes three sections of mooring cables made of different materials, namely, a first mooring cable located in the upper section, a carbon fiber composite mooring cable located in the middle section, and a second mooring cable located in the lower section. The sections of the cable system are connected by a mechanical connection structure. The first mooring cable is led onto the floating platform through a fairlead and wound onto a winch, a tension meter is installed between the first mooring cable and the carbon fiber composite mooring cable, displacement meters are installed in the anchors at both ends of the carbon fiber composite mooring cable, a strain meter is installed on the second mooring cable, and the end of the second mooring cable is connected to a gravity anchor foundation; The data line of the displacement meter and the data line of the strain meter naturally extend upward to the platform; Some of the carbon fiber composite rods in the carbon fiber composite mooring cable are embedded with optical fibers, and the carbon fiber composite rods embedded with optical fibers form intelligent carbon fiber composite rods. The optical fibers and the tension meter data line are led out from the end of the carbon fiber composite mooring cable and indexed above the water surface along the first mooring cable. The end of the optical fiber is connected to a related demodulator device, and the end of the tension meter data line is connected to a related data acquisition device.

2. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 1, characterized in that: The carbon fiber composite mooring cable comprises: a carbon fiber composite rod, a high-strength material belt and a protective cover, wherein a plurality of carbon fiber composite rods are arranged in parallel and twisted with a small torsion angle, the carbon fiber composite rod group is wrapped with a high-strength material belt, and two inner and outer protective covers are added on the outside to protect the internal structure, and the optical fiber is implanted in some of the carbon fiber composite rods in the carbon fiber composite rod group.

3. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 2, characterized in that: The number of carbon fiber composite rods with embedded optical fibers in the carbon fiber composite mooring cable is not less than one third of the total number of carbon fiber composite rods.

4. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 1, characterized in that: The first mooring cable is a polymer synthetic fiber cable, The upper end of the carbon fiber composite mooring cable is anchored into the first anchor, the outer thread processed on the outer cylinder of the first anchor is screwed with the inner thread of the inner hole of the first lifting ear, a space is left between the bottom plate of the first anchor and the bottom plate of the first lifting ear, the carbon fiber composite rod of the carbon fiber composite mooring cable passes through the bottom plate of the first anchor, a first displacement meter is installed on a plurality of carbon fiber composite rods and connected to the first positioning screw rod, the optical fiber implanted in the carbon fiber composite rod is led out from the end of the carbon fiber composite rod and then connected to the armored optical fiber in the space between the bottom plate of the anchor and the bottom plate of the first lifting ear, one armored optical fiber is connected to multiple fiber cores, a hole is opened on the bottom plate of the first lifting ear, the armored optical fiber in the bottom plate of the first lifting ear is led out of the hole to the first lifting ear, and waterproof glue is injected into the hole; The armored optical fiber and the tensiometer data line are arranged in parallel and protected by a casing. They are attached to the polymer synthetic fiber cable and led onto the floating platform together. The upper end of the first lifting ear is connected to the insertion end of the first shackle, the upper part of the first shackle is connected to the second shackle, the second shackle is connected to the tension meter, the upper end of the tension meter is connected to the third shackle, and the upper part of the third shackle is connected to the chicken heart eye ring and the polymer synthetic fiber cable.

5. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 4, characterized in that: The second mooring cable is a steel anchor chain, the lower end of the carbon fiber composite mooring cable is anchored into the second anchor, the outer cylindrical surface of the second anchor is processed with an external thread which is screwed into the inner thread of the inner hole of the second lifting ear, a space is left between the bottom plate of the second anchor and the bottom plate of the second lifting ear, the carbon fiber composite rod of the carbon fiber composite mooring cable passes through the bottom plate of the second anchor, and a plurality of carbon fiber composite rods are selected from the carbon fiber composite rods extending out of the bottom plate of the anchor, the center points of the plurality of carbon fiber composite rods are equidistant from the center of the anchor, and the center points of the plurality of carbon fiber composite rods are arranged symmetrically with respect to the center of the anchor; Among the plurality of carbon fiber composite rods, the end of each carbon fiber composite rod is connected to a probe of the displacement meter through a connecting cap; Two connecting metal sheets, one end of which is symmetrically clamped on both sides of the displacement meter and fixedly connected to the displacement meter through a first fixing bolt, and the other end of which is symmetrically clamped on both sides of the positioning screw rod and fixedly connected to the positioning screw rod through a second fixing bolt; When the carbon fiber composite rod in the anchor slips relative to the anchor, the connecting cap moves axially with the carbon fiber composite rod, driving the probe of the displacement meter to move axially. The average displacement measured by several displacement meters is the anchor slip amount. The lower end of the second lifting ear is connected to the insertion end of the fourth shackle, and the lower end of the fourth shackle is connected to the steel anchor chain segment, wherein the steel anchor chain segment is provided with an anchor chain ring, and two stress gauges are welded on the anchor ring; the terminal end of the steel anchor chain segment is fixed on a gravity anchor foundation, and the foundation adopts a square prism form with a concave bottom.

6. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 5, characterized in that: Three carbon fiber composite rods are selected from the carbon fiber composite rods extending out of the anchor bottom plate, the center points of the three carbon fiber composite rods are equidistant from the center of the anchor, and the lines connecting the center points of the three carbon fiber composite rods and the center of the anchor form 120° with each other.

7. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 5, characterized in that: The strain gauge is a vibrating-wire strain gauge. A connecting anchor ring in the anchor chain ring is cut into two half anchor rings. The vibrating-wire strain gauge is connected between the two half anchor rings. The data line of the vibrating-wire strain gauge is led outward from the adapter and is provided with a protective cover.

8. The carbon fiber composite combined mooring cable system for offshore floating structures according to claim 1, characterized in that: The displacement meter is an underwater micro displacement meter.

9. The self-monitoring method for a carbon fiber composite combined mooring cable system for an offshore floating structure according to any one of claims 1 to 8, characterized in that: The real-time strain data of the smart carbon fiber composite rod inside the carbon fiber composite mooring cable is obtained through the optical fiber implanted in the carbon fiber composite mooring cable; The stress data measured by the tensiometer is used to obtain the distribution of the strain difference Δε along the length direction of the cable under a certain stress difference Δσ. For an intact composite rod, the distribution of the strain difference Δε is a horizontal straight line. If a sudden jump occurs in the distribution diagram, the section with the sudden jump is the damaged section. The stiffness distribution of the composite rod is calculated by E = Δσ / Δε. The damage stiffness value Cd of the damaged section is equal to the initial stiffness E0 minus the stiffness value Ed of the damaged section, that is, Cd = E0-Ed; Finally, the damage location and size are determined according to the anchor slip detected by the displacement meter inside the carbon fiber composite mooring cable, and the damage state of the entire carbon fiber composite mooring cable is judged.

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