Large-tonnage fiber composite flexible cable anchoring method and mooring cable
Through the positioning anchor plate and composite clip design of large tonnage fiber composite flexible cables, the self-weight, corrosion and bending performance problems of traditional mooring cables in marine environments are solved, and efficient and reliable anchoring and long-life FRP cable applications are achieved.
Patent Information
- Application Number
- CN202510698648.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-28
- Publication Date
- 2025-07-11
AI Technical Summary
Traditional mooring cable materials such as wire ropes and synthetic fiber ropes have problems such as heavy self-weight, easy corrosion, wear, high creep rate and low strength conversion efficiency in marine environments. FRP cables have defects such as poor bending performance, easy cracking, and unsuitable for repeated bending coils, which affects their application in deep-sea mooring systems.
The flexible cable of large tonnage fiber composite material is adopted. The combination design of the anchor plate and composite material clips is designed to form a bend and anchor point. The bending performance of FRP flexible stranded threads is used to improve the toughness of the resin matrix with a toughening agent, so as to achieve self-anchoring and easy replacement.
It improves anchoring efficiency and ultimate bearing capacity, enhances the bending fatigue performance of FRP materials, ensures excellent tensile strength, corrosion resistance and toughness in marine environments, and extends the service life to more than 100 years.
Smart Images
Figure CN120288180A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical fields of ocean engineering and composite cable technology, and in particular to a method for anchoring and connecting large-tonnage fiber composite flexible mooring cables. Background Art
[0002] The mooring cables in traditional mooring systems mainly rely on steel ropes and synthetic fiber ropes, and both of these materials have certain limitations. Steel ropes are restricted in use due to their large self-weight, low free breaking length, and easy corrosion in the marine environment; while synthetic fiber ropes face problems such as easy wear, high creep rate, and low strength conversion efficiency, and these deficiencies affect their long-term performance and reliability.
[0003] As a new material, Fiber Reinforced Polymer (FRP) has achieved remarkable application results in the reinforcement and renovation of civil transportation infrastructure due to its characteristics such as light weight and high strength, excellent corrosion resistance and fatigue resistance, and good processing performance. Nowadays, FRP is gradually expanding into the field of improving the mechanical and durability performance of new structures and becoming a new favorite in demonstration applications. However, due to the anisotropic characteristics of FRP materials - that is, they have excellent mechanical properties along the fiber direction, but are weak in transverse compression and shear - the composite cable structure has become one of the best choices to exert the high performance of FRP. It should be noted, however, that FRP cables also have problems with poor bending performance, the matrix is prone to bending and cracking, and it is not suitable for repeated bending and coiling operations. In addition, it also shows poor ductility and tends to brittle failure.
[0004] In order to overcome the challenges of FRP materials in aspects such as easy cracking of the matrix and difficult bending and coiling, and to promote its application in new mooring systems, it is urgent to develop a large-tonnage FRP flexible cable that can be flexibly bent and coiled, achieve self-anchoring, and is easy to replace. This innovative design will not only greatly expand the application scope of FRP materials, but also bring more reliable and efficient solutions to fields such as ocean engineering.
[0005] FRP materials have successfully overcome some of the inherent defects of traditional steel ropes and synthetic fiber ropes and can be optimized according to specific application scenarios, which makes it show broad application prospects in deep-sea mooring systems. In view of this, combining the structural characteristics of steel ropes, synthetic fiber ropes, and FRP cables, the FRP flexible cable can be optimized to construct a cable anchoring system that is both safe and efficient and has a long service life. This not only helps to promote the research and development of new all-sea-depth, non-pumping, and large-capacity ocean mooring systems, but also greatly improves the performance and durability of ocean infrastructure, providing strong support for future ocean development. Summary of the Invention
[0006] To achieve the above object, the present invention provides a method for anchoring a large-tonnage fiber composite flexible cable and a mooring cable.
[0007] The technical solution adopted by the present invention is as follows:
[0008] A method for anchoring a large-tonnage fiber composite flexible cable. The large-tonnage fiber composite flexible cable is composed of multiple FRP flexible stranded wires. A positioning anchor plate and composite clamping pieces are used for the anchor. The positioning anchor plate is provided with an anchor hole group for anchoring each FRP flexible stranded wire. The anchor hole group is composed of a first tapered hole and a second tapered hole. The small-hole end of the first tapered hole is located inside the positioning anchor plate, and the small-hole end of the second tapered hole is located outside the positioning anchor plate. The method for anchoring a large-tonnage fiber composite flexible mooring cable is as follows:
[0009] The anchoring end of each FRP flexible stranded wire of the large-tonnage fiber composite flexible cable passes through the first tapered hole on the inner side of the positioning anchor plate, forms a bending part outside the positioning anchor plate, and then passes through the second tapered hole on the outside of the positioning anchor plate. The distance of the bending part along the direction of the positioning anchor plate is greater than the distance between the first tapered hole and the second tapered hole.
[0010] From the outside of the positioning anchor plate, insert the first composite clamping piece into the first tapered hole, so that the FRP flexible stranded wire and the positioning anchor plate form a first anchoring point at the position of the first tapered hole; from the inside of the positioning anchor plate, insert the second composite clamping piece into the second tapered hole, so that the FRP flexible stranded wire and the positioning anchor plate form a second anchoring point at the position of the second tapered hole.
[0011] The bending part is approximately elliptical in shape. The major axis a and minor axis b of the elliptical contour satisfy: a:b = 5:3, 10D ≤ a ≤ 15D, 6D ≤ b ≤ 9D, where D is the diameter of the BFRP flexible stranded wire. Bend according to the bending principle of giving full play to the bending ability of the material itself as much as possible, without applying too much artificial force. The ratio of the major axis a to the minor axis b of the bending part is approximately a:b = 5:3, which can minimize the pre-damage of the material.
[0012] The anchor hole groups are evenly distributed in a circular ring; the first tapered hole and the second tapered hole of the anchor hole group are located radially, the first tapered hole is located in the inner circle, and the second tapered hole is located in the outer circle.
[0013] The inclination angle of the first tapered hole is 3 - 5°; the inclination angle of the second tapered hole is 3 - 5°.
[0014] The FRP flexible stranded wire is formed by twisting a number of FRP flexible bars.
[0015] The FRP flexible bar is composed of resin and fiber materials, and 10 ± 2 wt% toughening agent is added to the resin.
[0016] The fiber material of the FRP flexible tendon is one or a mixture of carbon fiber, basalt fiber, glass fiber, and aramid fiber.
[0017] Each FRP flexible strand is made by twisting at least 7 FRP flexible tendons arranged in a regular hexagon cross-section synchronously. The total number of required FRP flexible tendons increases with the increase in the cross-section layer number of each FRP flexible strand, and the ultimate bearing capacity of the FRP flexible strand also increases accordingly. The total number of the nth layer is 3n 2 -3n + 1, where n is a natural number.
[0018] The composite wedge is composed of a chopped fiber resin mixture, and the inclination angle of the wedge is 3 - 5°.
[0019] The present invention also provides a large-tonnage fiber composite flexible mooring cable, which has a mooring end that can be sleeved, and the mooring end is anchored by using the above-mentioned large-tonnage fiber composite flexible mooring cable anchoring method.
[0020] The beneficial effects of the present invention:
[0021] 1. The FRP flexible strand of the present invention has the characteristics of self-anchoring, high anchoring, and easy replacement. Most of the commonly used FRP cables at present adopt bonded extrusion type grouting anchors, which need to inject grouting material into the inner tapered steel anchor barrel, and use the bonding effect of the grouting material and the extrusion effect of the inner tapered steel anchor barrel to achieve the anchoring effect. This method has the disadvantages of low anchoring efficiency, complex manufacturing process, and difficult replacement. Therefore, the present invention forms a bent part of an elliptical closed contour between the first anchoring point and the second anchoring point for each FRP flexible strand, and uses a composite wedge for reverse extrusion to fix it, greatly improving the ultimate bearing capacity of the anchored cable body, and thus greatly improving the anchoring effect. The elliptical anchoring section of the cable body is connected to the fixed position through a U-shaped shackle and an offshore platform steel anchor chain or the seabed. The entire manufacturing process is simple, and the cable body is easy to replace without affecting the group anchor effect.
[0022] 2. The FRP flexible strand of the present invention has the characteristics of easy bending and coiling. Most of the commonly used FRP cables at present are brittle due to the three-dimensional network cross-linked structure formed by the curing reaction of epoxy resin in the matrix material. Therefore, during the bending fatigue process, the resin matrix is prone to cracking, causing damage phenomena such as wire breakage of the FRP cable, which is not conducive to the long-term service of the structure. Therefore, by reducing the elastic modulus of the resin matrix and improving the toughness of the matrix, the bending fatigue performance of the FRP material can be effectively improved. The present invention adds a toughening agent to the epoxy resin matrix. The toughening agent will automatically generate micron-sized elastic rubber balls during the curing process and be evenly distributed in the cured product, which can greatly improve the toughness of the epoxy resin cured product, resist crack propagation, and thus prepare a resin matrix with low elastic modulus and high toughness.
[0023] 3. The FRP flexible stranded cable of the present invention has excellent long-term use performance. Compared with traditional steel ropes and synthetic fiber ropes, the FRP flexible stranded cable exhibits excellent tensile strength, corrosion resistance, and toughness. In the face of erosion factors such as acid, alkali, salt, and ultraviolet rays, it can maintain excellent durability. Especially in the marine environment, the FRP structure is expected to have a service life of more than 100 years, demonstrating its extraordinary ability to resist harsh corrosion conditions. In addition, the fatigue strength of FRP and its ability to withstand fatigue load stress are significantly better than those of steel and synthetic fiber materials, further highlighting its advantages in long-term performance and reliability. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Schematic diagram of the anchoring structure of the large-tonnage fiber composite flexible mooring cable of the present invention.
[0025] Figure 2 Longitudinal sectional view of the anchoring structure of the large-tonnage fiber composite flexible mooring cable of the present invention.
[0026] Figure 3 Schematic diagram of the structure of the positioning anchor plate of the present invention, where (a) is the front view; (b) is the sectional view.
[0027] Figure 4 Process flow chart of the large-tonnage fiber composite flexible mooring cable and its anchoring connection prepared in Example 1.
[0028] Figure 5 Comparison diagram of two different anchoring forms prepared in Example 1, where (a) uses the anchoring of the present invention; (b) uses single-sided composite material clamp wedge anchoring.
[0029] Figure 6 Comparison diagram of the load-displacement change curves of the BFRP flexible stranded cable specimens under the anchoring form of the present invention and single-sided composite material clamp wedge anchoring in Example 1.
[0030] Figure 7 Elliptical contour diagram of the anchoring section of the FRP flexible stranded cable described in Example 2.
[0031] Figure 8 Comparison diagram of the load-displacement change curves of different elliptical contour dimensions of the anchoring section of the FRP flexible stranded cable described in Example 2.
[0032] Wherein: 1. FRP flexible tendon; 2. FRP flexible stranded cable; 3. Composite material clamp; 4. Positioning anchor plate. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be combined with the attachedFigure 4 and One the following preferred embodiments are used to clearly and completely describe the technical solutions of the present invention.
[0034] Example 1
[0035] The present invention provides a method for anchoring a large-tonnage fiber composite flexible mooring cable. The FRP flexible strand 2 is anchored on the positioning anchor plate 4 through the composite material clamp 3. The FRP flexible strand 2 is formed by twisting a plurality of FRP flexible bars 1. The positioning anchor plate 4 is provided with two concentric conical holes. The conical holes in the inner ring and the outer ring along the same radial direction are a group, and the conical mouth directions are opposite. The FRP flexible strand passes through the small end of the inner ring conical hole, bends into an ellipse in the anchoring section, and passes out from the large end of the outer ring conical hole in the same radial direction.
[0036] The anchoring section of the FRP flexible strand 2 is bent into an elliptical shape. The anchoring of a single FRP flexible strand is completed by installing the composite material clamp 3 in the hole of the positioning anchor plate, and the remaining FRP flexible strands are anchored in an annular array in sequence.
[0037] The fiber material of the FRP flexible bar is one or more of non-metallic fiber materials such as carbon fiber (CFRP), basalt fiber (BFRP), glass fiber (GFRP), and aramid fiber (AFRP) with high strength and excellent durability.
[0038] Each FRP flexible strand is at least made by synchronously twisting 7 FRP flexible bars arranged in a regular hexagon cross-section. The total number of required FRP flexible bars increases with the increase of the cross-section layer number of each FRP flexible strand, and the ultimate bearing capacity of the FRP flexible strand also increases accordingly. Taking the central FRP flexible bar as the first layer, and sequentially outwards, the total number of 2 layers is 7, the total number of 3 layers is 19, the total number of 4 layers is 37, and so on. The total number of n layers is 3n 2 -3n + 1, where n is a natural number.
[0039] The anchoring section of the FRP flexible strand is bent into an approximately elliptical shape. The major axis a and minor axis b of the elliptical contour should be controlled as: a:b = 5:3, 10D ≤ a ≤ 15D, and the minor axis 6D ≤ b ≤ 9D, where D is the diameter of the BFRP flexible strand.
[0040] The composite material clamp is mainly composed of a chopped fiber resin mixture, and the wedge angle of the clamp is controlled within the range of 3 - 5°.
[0041] A method for anchoring a large-tonnage fiber composite flexible mooring cable provided by the present invention is as follows:
[0042] The first step is the stranding and twisting and marking of a single BFRP flexible strand 2.
[0043] First, use a thin plate with small holes (such as polyvinyl chloride material, PVC) to twist and ply 7 basalt fiber reinforced polymer (BFRP) flexible tendons 1 with a diameter of 3 mm to form a BFRP flexible cable 2 with a certain cross-sectional shape. The shape of the cable cross-section is a regular hexagon. The BFRP flexible tendon 1 is made of basalt fiber with a linear density of 1200 tex, and the resin matrix is ER7121 epoxy resin. 10 ± 2 wt% of QS-VA-3 toughening agent is added to the epoxy resin. Use a paint pen and a steel ruler to measure and mark the anchorage area of the BFRP flexible cable 2, so as to accurately locate the anchorage area of the cable. The preparation method of the BFRP flexible cable is a general method in the art.
[0044] In this embodiment, the BFRP flexible cable 2 is twisted by 7 BFRP flexible tendons 1. The diameter d of a single BFRP flexible tendon 1 is 3 mm, and the diameter of the twisted BFRP flexible cable 2 is D = 9 mm. In other embodiments, the diameter of a single BFRP flexible tendon 1 can also be selected within the range of 1 - 5 mm. The central flexible tendon is arranged in a straight line, and the remaining flexible tendons increase layer by layer from the inside to the outside.
[0045] Second step, the bending and anchoring of a single BFRP flexible cable 2.
[0046] Insert the end of the BFRP flexible cable 2 twisted in the first step into the small end of the tapered hole in the inner ring of the positioning anchor plate 4 until the position marked by the paint pen in the first step is just flush with the opening of the tapered hole. Slowly bend the inserted cable part into an elliptical shape, and the end of the cable exits from the large end of the outer ring tapered hole in the same radial direction. The end of the cable extends 2 - 3 cm from the large end of the outer ring tapered hole. Set the major axis a of the elliptical contour to be 15D = 135 mm and the minor axis b to be 9D = 81 mm. Install the pre-prepared composite clamping pieces 3 at the large ends of the two tapered holes in the same radial direction to achieve the limit anchoring of a single cable body. The twisting method of the BFRP flexible cable 2 is an existing technology, and the twist pitch is preferably 12 - 20 times the overall nominal diameter of the BFRP flexible cable 2.
[0047] Compare the anchoring effect of the single BFRP flexible cable 2 and the bending part anchoring form made according to the above steps of the present invention with the BFRP flexible cable 2 anchored by a single-sided composite wedge clamping piece conventionally. Figure 5 It is a comparison diagram of specimens under two different anchoring forms.
[0048] Six specimens were made using the above steps for testing. Among them, 3 specimens of the present invention's anchorage were made, namely Invention Anchorage Specimen 1, Invention Anchorage Specimen 2, and Invention Anchorage Specimen 3. Invention Anchorage Specimen 1, Invention Anchorage Specimen 2, and Invention Anchorage Specimen 3 are the same. Each of the three specimens consists of 3 BFRP flexible cable strands 2 with a diameter D = 9 mm and the bending part anchorage form of the present invention. Additionally, 3 BFRP flexible cable strands 2 with a diameter D = 9 mm were made using the above steps, and unilateral composite clamping pieces 3 were installed to make three identical specimens, namely Unilateral Composite Wedge Clamping Piece Anchorage Specimen 1, Unilateral Composite Wedge Clamping Piece Anchorage Specimen 2, and Unilateral Composite Wedge Clamping Piece Anchorage Specimen 3. An MTS material tensile testing machine and displacement control method were used for loading, and the specimens were continuously loaded at a constant speed of 2 mm / min until complete failure occurred. The test results are as Figure 6 shown, Figure 6 the load-displacement performance of a single BFRP flexible cable strand 2 with a diameter of 9 mm using the bending part anchorage form in the present invention, and it was compared with the load-displacement performance of the same cable strand using the wedge-shaped anchorage form of the unilateral composite clamping piece 3. The abscissa represents the longitudinal displacement of the cable strand at the loading end during the tensile process, and the ordinate represents the change in the bearing capacity of the cable strand during the tensile process. From Figure 6 it can be seen that compared with the wedge-shaped anchorage of the unilateral composite clamping piece 3, the ultimate bearing capacity of the cable strand using the anchorage form of the present invention can reach about 120 kN, which is 22% higher than the ultimate bearing capacity under the wedge-shaped anchorage of the unilateral composite clamping piece 3, verifying the advantages of using the anchorage form described in the present invention.
[0049] Example 2
[0050] Figure 7 and Figure 8 compared the anchorage effects after changing the major axis and minor axis sizes of the elliptical contour in the anchorage area of the FRP flexible cable strand 2. Taking the BFRP flexible cable strand 2 with a diameter D = 9 mm prepared in Example 1 above as the research object, referring to Figure 7 , the major axis of the elliptical contour is a, the minor axis is b, the ratio of the major axis to the minor axis is controlled to be 5:3, and 4 types of specimens with different elliptical contour sizes are set. Among them, for Specimen I, a = 5D = 45 mm, and the minor axis b = 3D = 27 mm; for Specimen II, a = 10D = 90 mm, and the minor axis b = 6D = 54 mm; for Specimen III, a = 15D = 135 mm, and the minor axis b = 9D = 81 mm; for Specimen IV, a = 20D = 180 mm, and the minor axis b = 12D = 108 mm. By Figure 8As can be seen from the comparison results shown, the ultimate bearing capacity of Specimen Ⅰ is the lowest, indicating that the relatively small contour size caused pre-damage to the anchorage section of the BFRP flexible cable 2. As the contour size increases, the ultimate bearing capacities of Specimens Ⅱ, Ⅲ, and Ⅳ gradually become stable. Among them, the ultimate bearing capacity of Specimen Ⅲ reaches the maximum, and the ultimate bearing capacity of Specimen Ⅳ is slightly lower than that of Specimen Ⅲ. Generally speaking, a larger contour size slows down the pre-damage of the cable to a certain extent. The major axis and minor axis of the elliptical contour should be controlled within: 10D ≤ a ≤ 15D, and the minor axis 6D ≤ b ≤ 9D, where D is the diameter of the BFRP flexible cable.
Claims
1. A method for anchoring a large-tonnage fiber composite flexible cable. The large-tonnage fiber composite flexible cable is composed of multiple FRP flexible stranded cables, and is characterized in that: An anchor is used with a positioning anchor plate and composite material clamping pieces. An anchoring hole group for anchoring each FRP flexible strand cable is arranged on the positioning anchor plate. The anchoring hole group is composed of a first tapered hole and a second tapered hole. The small-hole end of the first tapered hole is located inside the positioning anchor plate, and the small-hole end of the second tapered hole is located outside the positioning anchor plate. The anchoring method for large-tonnage fiber composite flexible mooring cables is as follows: The anchoring end of each FRP flexible strand cable of the large-tonnage fiber composite flexible mooring cable passes through the first tapered hole on the inner side of the positioning anchor plate, forms a bending part outside the positioning anchor plate, and then passes through the second tapered hole on the outside of the positioning anchor plate. The distance of the bending part along the direction of the positioning anchor plate is 2-3 times the distance between the first tapered hole and the second tapered hole; From the outside of the positioning anchor plate, insert the first composite material clamping piece into the first tapered hole, so that the FRP flexible strand cable and the positioning anchor plate form a first anchoring point at the position of the first tapered hole; From the inside of the positioning anchor plate, insert the second composite material clamping piece into the second tapered hole, so that the FRP flexible strand cable and the positioning anchor plate form a second anchoring point at the position of the second tapered hole.
2. A method for anchoring a large-tonnage fiber composite flexible cable according to claim 1, characterized in that: The bending part is approximately elliptical in shape, and the major axis a and minor axis b of the elliptical contour satisfy: a:b = 5:3, 10D ≤ a ≤ 15D, where D is the diameter of the BFRP flexible strand cable.
3. A method for anchoring a large-tonnage fiber composite flexible cable according to claim 1, characterized in that: The anchoring hole groups are evenly distributed in a circular ring; the first tapered hole and the second tapered hole of the anchoring hole group are in the radial direction, the first tapered hole is located in the inner circle, and the second tapered hole is located in the outer circle.
4. A method for anchoring a large-tonnage fiber composite flexible cable according to claim 1, characterized in that: The inclination angle of the first tapered hole is 3-5°; the inclination angle of the second tapered hole is 3-5°.
5. A method for anchoring a large-tonnage fiber composite flexible mooring cable according to claim 1, characterized in that: The FRP flexible strand cable is formed by twisting a plurality of FRP flexible ribs.
6. A method for anchoring a large-tonnage fiber composite flexible mooring cable according to claim 5, characterized in that: The FRP flexible rib is composed of resin and fiber material, and 10 ± 2wt% of toughening agent is added to the resin.
7. A method for anchoring a large-tonnage fiber composite flexible mooring cable according to claim 6, characterized in that: The fiber material of the FRP flexible rib is one or a mixture of carbon fiber, basalt fiber, glass fiber, and aramid fiber.
8. A method for anchoring a large-tonnage fiber composite flexible mooring cable according to claim 6, characterized in that: Each of the FRP flexible stranded cables is made by synchronously twisting at least 7 FRP flexible bars arranged in a regular hexagon cross-section. The total number of required FRP flexible bars increases with the increase in the cross-section layers of each FRP flexible stranded cable, and the ultimate bearing capacity of the FRP flexible stranded cable also increases accordingly. The total number of the nth layer is 3n 2 -3n + 1, where n is a natural number.
9. A method for anchoring a large-tonnage fiber composite flexible mooring cable according to claim 1, characterized in that: The composite material clamping piece is composed of a chopped fiber resin mixture, and the inclination angle of the clamping piece is 3-5°.
10. A large-tonnage fiber composite flexible mooring cable, having a mooring end that can be sleeved, is characterized in that, The mooring end is anchored by using the anchoring method for large-tonnage fiber composite flexible mooring cables described in any one of claims 1-9.