CN120016378B

CN120016378B - Bending limiter and submarine cable protection device

Info

Publication number: CN120016378B
Application number: CN202510472871.1A
Authority: CN
Inventors: 吴征奇; 陈旭光; 高成伟; 闫志琳
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2025-04-16
Filing date: 2025-04-16
Publication date: 2025-07-11
Anticipated expiration: 2045-04-16
Also published as: CN120016378A

Abstract

The present invention discloses a bend limiter and a submarine cable protection device, wherein the male head of the bend limiter has multiple arc surfaces with different curvatures, and the groove also has arc surfaces with different curvatures. The side surface of the outer locking portion close to the male head has a first angle relative to the central axis, and the side surface of the female head away from the male head has a second angle relative to the central axis. The first angle and the second angle are substantially the same, which increases the contact area and improves the force distribution, so that the bend limiter has better fatigue resistance and reliability during long-term service. In addition, a reinforcer and a barb device of a submarine cable protection device are proposed, which adopt an embedded reinforcement device structure to enhance the connection strength, can significantly improve the connection strength and pull-off resistance of the submarine cable protection device, and the barb device can be connected to the reinforcer in a wedge shape to ensure the stability of the system in long-term operation on the seabed, and effectively reduce the risk of pull-off caused by scouring and fatigue loading during long-term service.

Description

Bending limiter and submarine cable protection device

Technical Field

The invention relates to the technical field of marine cable protection of offshore wind power, in particular to a bending limiter and a marine cable protection device.

Background

In recent years, the development and utilization of ocean resources are continuously accelerated worldwide, offshore wind power and photovoltaic projects are rapidly developed, and the sea cable protection requirement is greatly increased. However, submarine cables are subjected to dynamic loads such as waves and tide for a long time, and the scouring problem has become a key bottleneck affecting the reliability of the submarine cables. According to statistics, in the insurance claim case of the offshore wind power and photovoltaic projects, the sea cable fault paying ratio is up to 87.6%, wherein the average fault rate of the sea cable protecting device, which is used as a bend limiter of the sea cable protecting device, is up to 50% in the sea area with poor sea conditions.

Under the scouring action, the sea cable at the mud inlet end is exposed, so that the length of the suspension span section is increased, and further the frequency and the amplitude of sea cable shaking are increased. The bending limiter is easy to generate fatigue damage under the action of long-term alternating load, and finally causes fracture or falling off. The traditional half design of the bending limiter structure used at home still remains overseas for decades, and the structure is easy to form stress concentration when the male and female heads are in local contact, so that fracture failure is caused. In addition, the bending limiter has higher cost, and the existing domestic improvement is mainly focused on material optimization so as to improve the tensile strength, but the problem of core structural design is not broken through yet. In addition, the innovation of the matched protection device of the submarine cable access fan is insufficient, and the whole protection scheme is not systematic and optimally designed.

Chinese patent document CN211508560U discloses a protection device for wind power sea cable, comprising a central positioning protection mechanism, a bending protection mechanism and a bending limiting mechanism, which are connected in sequence. The central positioning protection system of the head end is embedded into the J-shaped pipe on the fan, and the bending protection mechanism and the bending limiting mechanism are positioned at the sea cable of the outer suspension span of the J-shaped pipe to provide protection for the sea cable so as to prolong the service life of the sea cable. The scheme still has the following problems that firstly, the traditional design is adopted for the bending limiter structure, stress concentration is easy to generate during long-term service, the fracture risk is increased, the service life of the submarine cable is further influenced, and secondly, the rigid flange is adopted as a connecting piece at the front end of the flexible bending prevention pipe, but in the connecting mode, the tightness between a flexible material and the flange is limited, the connecting part bears a large load, the pull-off risk exists under the long-term action, and the reliability of the system is reduced.

In addition, the inventor also provides a bending limiter structure (CN 119518579A) which comprises a plurality of unit limiters which are connected end to end in sequence, wherein each unit limiter is formed by splicing two limiting monomers which are internally provided with cable through holes and are symmetrical in central axis, each limiting monomer comprises a female head part, a male head part and a neck locking part, the female head part and the male head part are positioned at two ends of the neck locking part, the outer surface of the female head part is of a semicircular convex surface structure, the inner surface of the male head part is provided with a semicircular concave surface structure, the concave surface structure of the male head part wraps the convex surface structure of the adjacent female head part and has a gap, so that the female head part can rotate in the male head part, and the neck locking part of each limiting monomer is provided with a damage early warning device. However, although the bending degree of the submarine cable can be effectively limited by the bending limiter structure, the capability of solving the stress concentration is still limited according to the further research of the structure, so that how to optimize the structural arrangement of the bending limiter is a key for solving the problem of stress concentration and reducing the fracture risk.

Disclosure of Invention

Aiming at the problems of local stress concentration, high long-term service fault rate and poor reliability of the existing bending limiter and the defects of the matched submarine cable protection device in tensile stripping performance, the invention provides the bending limiter and the submarine cable protection device.

The invention provides a bending limiter which comprises two bending limiter subunits which are symmetrical in central axis, wherein the two bending limiter subunits are detachably connected, a submarine cable passes through a cavity formed by the centers of the two bending limiter subunits, each bending limiter subunit comprises a male head, a female head, a connecting neck, an outer locking part and a transitional neck which are sequentially arranged, a groove is formed in the inner side of the female head, the male head is provided with a plurality of sections of arc surfaces with different curvatures, the groove is also provided with an arc surface with different curvatures, the side surface of the outer locking part, which is close to one side of the male head, is provided with a first included angle relative to the central axis, the side surface of the female head, which is far away from the male head, is provided with a second included angle relative to the central axis, and the first included angle and the second included angle are approximately the same.

Further, the connecting neck is formed by a plurality of circular arcs with different curvatures, and/or the transition neck is provided with a circular arc surface with a large curvature.

Further, bolt holes are formed in the bending limiter sub-units, and the two bending limiter sub-units are connected through bolts.

In addition, the invention also provides a submarine cable protection device which comprises the bending limiter and a reinforcement connected with the bending limiter, wherein the reinforcement comprises a connecting end head, a connecting cylinder body and a connecting tail part, and the shape and the size of the connecting tail part are the same as those of a male head of the bending limiter.

Further, the inner wall of the connecting end is provided with an embedded reinforcing device, the embedded reinforcing device comprises a reinforcing rod, a U-shaped part and a fixing ring, the embedded reinforcing device is embedded into the connecting end through the reinforcing rod, the U-shaped part is connected with the reinforcing rod, the U-shaped part is uniformly distributed along the ring shape relative to the central axis, the fixing ring is tightly attached to the inner wall of the connecting end, and the fixing ring is used for integrally connecting the U-shaped part which is distributed in the ring shape.

Further, each of the U-shaped members is connected to 3 of the reinforcing rods, and/or the embedded reinforcing means is made of stainless steel.

Further, the reinforcement still includes barb device, barb device the reinforcement with the curved ware of limit links to each other in proper order, barb device includes the steel body, is located protruding and the wedge of setting on the tail end on the steel body, protruding opening that is used for the card income fan lateral wall, the wedge be used for with U type spare carries out wedge connection.

Further, a threaded hole is formed in the wedge block, and the threaded hole is connected with a bolt hole formed in the U-shaped piece through a bolt.

Further, the embedded reinforcement means is made of stainless steel and/or the barb means is made of stainless steel.

The fixing ring is integrally processed, and/or the U-shaped piece is integrally processed.

Further, the material of the bending limiter is polyurethane, and/or the material of the reinforcement is polyurethane.

The beneficial effects of the invention are as follows:

(1) The invention carries out structural optimization design on the bending limiter based on stress distribution, and specifically provides structural design optimization on each part of a male head, a female head, a connecting neck, an outer locking part and a transitional neck by optimizing the stress distribution of the bending limiter, so that the contact area is increased, the stress distribution is improved, the bending limiter has more excellent fatigue resistance and reliability in the long-term service process, and the structural display of numerical simulation and model test shows that the structural optimization can obviously improve the service life of the bending limiter and an integral system.

(2) Meanwhile, the invention provides a structural arrangement of the reinforcement device on the basis of structural optimization of the bending limiter, and the embedded reinforcement device structure is adopted to enhance the connection strength, so that the connection strength and the tensile stripping capacity of the submarine cable protection device can be obviously improved, and the stability of the system in long-term running on the seabed is ensured.

(3) In addition, the invention further provides a barb device on the basis of the submarine cable protection device, the barb device can be connected with the reinforcement in a wedge-shaped mode, and the barb device is combined with the reinforcement in a bolt connection mode, so that when the submarine cable protection device is in service on the sea floor, the special wedge-shaped connection can be gradually tightened after dislocation deformation, and meanwhile, the barb device is locked by the bolts, so that the pull-out risk caused by flushing and fatigue loading in the long-term service process is effectively reduced.

Drawings

FIG. 1 is a schematic view of a bending limiter connection according to the present invention;

FIG. 2 is a block diagram of a bend limiter and a bend limiter subunit according to the present invention;

FIG. 3 is a front view of a proposed bend limiter subunit of the present invention;

FIG. 4 is a top view of a proposed bend limiter subunit of the present invention;

FIG. 5 is a cross-sectional view taken along line A-A of FIG. 3;

FIG. 6 is a schematic diagram of the bending principle of the conventional bending limiter (left structure) and the bending limiter of the present invention (right structure);

FIG. 7 is a graph showing the results of a simulation calculation of the force and deflection values of a conventional bending limiter;

FIG. 8 is a simulation calculation result of the stress and deformation values of the bending limiter of the present invention;

FIG. 9 is a graph of impact test simulation results for the bend limiter of the present invention;

FIG. 10 is a graph of simulation results of a side pressure test of the bend limiter of the present invention;

FIG. 11 is a schematic diagram of the submarine cable protection device according to the present invention;

FIG. 12 is a cross-sectional view of a reinforcement structure according to the present invention;

figure 13 is a schematic view of the attachment of the reinforcement member to the barb structure in accordance with the present invention;

Figure 14 is a schematic view of the barb configuration as proposed in the present invention.

The reference numbers include 1. The stiffener, 11. The connection end, 12. The connection barrel, 13. The connection tail, 14. The embedded stiffener, 15. The stiffener, 16. The U-shaped piece, 17. The fixing ring, 2. The bending limiter, 21. The bending limiter subunit, 22. The male head, 23. The female head, 24. The connection neck, 25. The external locking part, 26. The transitional neck, 27. The groove, 28. The bolt hole, 3. The barb device, 31. The protrusion, 32. The steel body, 33. The wedge block, 4. The threaded hole, 5. The bolt, 6. The cavity, 7. The submarine cable, 81. The 1 st contact point, 82. The 2 nd contact point, 83. The 3 rd contact point, 84. The 4 th contact point, 85. The 5 th contact point, 86. The 6 th contact point, 87. The 7 th contact point, 88. The 8 th contact point, and 89. The 9 th contact point.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1-5, the present invention provides a technical solution, which includes two bending limiter subunits 21 having symmetrical central axes, wherein the two bending limiter subunits 21 are detachably connected, a submarine cable 7 passes through a cavity 6 formed by the centers of the two bending limiter subunits 21, each bending limiter subunit 21 includes a male head 22, a female head 23, a connecting neck 24, an outer locking portion 25 and a transitional neck 26, which are sequentially disposed, a groove 27 is disposed on the inner side of the female head 23, the male head 22 has a plurality of arc surfaces with different curvatures, the groove 27 also has arc surfaces with different curvatures, a side surface of the outer locking portion 25 on a side near the male head 22 has a first included angle with respect to the central axis, a side surface of the female head 23 on a side far from the male head 22 has a second included angle with respect to the central axis, and the first included angle and the second included angle are the same, so that a side surface of the outer locking portion 25 on a side surface of the female head 23 on a side far from the male head 22 contacts with a side surface of the female head 23.

It should be noted that the same meaning here should be about the same meaning because it is difficult to avoid that there is a certain production error, especially that there is a great uncertainty in the processing difficulty and accuracy for different materials, so about the same meaning is only required to be within a range that enables the two to form surface contact, and the difference may not be required to be exactly the same, such as a difference may be ±0.1 degrees, ±0.5 degrees, ±1 degrees, ±5 degrees or other angles depending on the material selection, which is required to be specified according to the production requirement at the processing angle, that is, the angle error of the two is not particularly large, resulting in a bonding form where the surface contact of the two cannot be achieved, but there may be a certain error or deviation.

The inner side of the female head is provided with a groove, and after the male head is inserted into the groove, local contact is formed when force is applied to the male head for locking. On one hand, the male head adopts the arc surfaces with different sections of curvatures, and the arc surfaces are connected through concave-convex transition and matched with the contact surfaces with corresponding shapes on the inner side of the female head, so that the stress of the male head and the female head can be ensured to be more uniform, the number of contact points between the male head and the female head groove is increased, and the stress concentration is reduced. On the other hand, the outer locking part is in non-contact with the adjacent bending limiter before the bending limiter is not subjected to force locking, and after the bending limiter is locked, the outer locking part is in contact with the female end part of the previous bending limiter, and the included angles of the end surfaces of the outer locking part and the female end part are approximately the same, so that the surface bonding between the outer locking part and the female end part can be ensured, the point contact stress mode of the traditional bending limiter is avoided, the stress area is greatly increased, and the local stress can be further dispersed by increasing the thickness of the structure, so that the integral fatigue resistance and reliability of the bending limiter are improved.

Further, the connecting neck portion is formed by a plurality of circular arcs with different curvatures.

Through the design of multistage camber circular arc connection, can make the limit curved ware after the closure, connect the neck and can fully contact with female head, improve the atress homogeneity and strengthen structural stability.

Further, the transition neck has an arcuate surface of large curvature.

The traditional bending limiter generally adopts a linear structure at the transition neck, so local stress concentration can be caused, and therefore, the concentrated stress at the outer locking part and the female head can be uniformly distributed to the whole bending limiter through designing the transition neck into an arc surface with large curvature, thereby reducing local stress peaks and improving the whole bearing capacity.

Further, the plurality of bending limiters 2 may be sequentially connected end to end through a male head 22 and a female head 23.

According to the bending limiting requirement of the submarine cable, the bending limiting devices can be connected end to end in sequence, and the requirements of different working conditions are met.

Further, the material of the bending limiter 2 is polyurethane.

Further, the two bending limiter sub-units are preferably detachably connected through bolts, the bending limiter sub-units are provided with bolt holes 28, and the number and positions of the bolt holes are arranged according to specific installation requirements.

As can be seen from fig. 6, the conventional bending limiter is designed to have only 2-3 contacts (1 st contact 81, 2 nd contact 82, 3 rd contact 83) during locking, but the present invention can increase the contact points to at least 6 (4 th contact 84, 5 th contact 85, 6 th contact 86, 7 th contact 87, 8 th contact 88, 9 th contact 89) by optimizing the structures of the male head, the female head, the connecting neck, the transitional neck and the external locking portion, so that the overall contact area is significantly increased, and the problem of local stress concentration is effectively reduced.

According to the numerical simulation analysis (see fig. 7 and 8) of the mechanical response and deformation behavior of the bending limiter structure, under the same loading condition, the traditional bending limiter has obvious stress concentration phenomenon, the maximum stress and deformation are mainly concentrated in the connecting neck region where the male head is contacted with the female head, the maximum equivalent (Mi Saisi) stress is 28MPa, the maximum logarithmic strain is 0.025, and the bending limiter belongs to a typical small deformation mode.

In contrast, the bending limiter structure is more uniform in overall stress, maximum stress and deformation occur in the transition neck region of the structure, the maximum Mi Saisi stress is only 13MPa, the maximum logarithmic strain is reduced by about 54% compared with the traditional structure, and the maximum logarithmic strain is 0.008 and is also in a small deformation range. The structure effectively weakens the local stress concentration phenomenon of the locking part, obviously improves the stress performance and the fatigue life of the bending limiter, and further enhances the protection capability and the service life of the submarine cable.

In order to further verify the durability of the bending limiter, a simulation test under the working conditions of impact load and side pressure load is carried out:

impact test simulation (FIG. 9) 80kg weights were free to fall from 80cm height against the surface of the bend limiter, and the simulation results showed that the maximum contact pressure of the bend limiter with the weight contact surface was 134kN and the maximum contact pressure of the bend limiter with the bottom plate contact surface was 187kN. The maximum equivalent stress is present in the fillet transition area contacted with the weight and the bottom plate, the value is 47MPa, the yield strength of the material is not reached, the structure is not obviously plastically deformed, and the use requirement under the impact working condition is met.

Side pressure test simulation (fig. 10) vertical compression load was applied stepwise through the load plate above the bend limiter, with the maximum equivalent stress being 45MPa when the compression load reached a maximum of 78kN, still below the material yield limit. The maximum deformation value of the bending limiter is 6mm, the bending limiter is negligible relative to the whole thickness, and the structural stability is good.

In summary, the bending limiter structure provided by the invention has excellent performances in stress distribution, impact resistance and pressure resistance, and is suitable for long-term service requirements in complex marine environments.

In addition, the invention also provides a submarine cable protection device, which comprises a bending limiter 2 and a reinforcement 1 connected with the bending limiter 2, wherein the reinforcement 1 comprises a connecting end head 11, a connecting cylinder 12 and a connecting tail 13, and the shape and the size of the connecting tail 13 are the same as those of a male head 22 of the bending limiter 2.

The shape and the size of the connecting tail part are the same as those of the male head of the bending limiter, so that the connecting tail part can be directly assembled and connected with the female head of the bending limiter, and the force transmission uniformity can be ensured, and the local stress concentration is avoided.

Further, the whole of the reinforcement 1 is conical and made of polyurethane material.

Further, the inner wall of the connecting end 11 is provided with an embedded reinforcing device 14, the embedded reinforcing device 14 comprises a reinforcing rod 15, a U-shaped piece 16 and a fixing ring 17, the embedded reinforcing device 14 is embedded into the connecting end 11 through the reinforcing rod 15, the U-shaped piece 16 is connected with the reinforcing rod 15, the U-shaped piece 16 is uniformly distributed along the ring shape relative to the central axis, the fixing ring 17 is tightly attached to the inner wall of the connecting end 11, and the fixing ring 17 connects the U-shaped pieces 16 which are distributed in the ring shape into a whole.

By the arrangement of the embedded reinforcing device, higher structural strength and impact resistance can be further provided.

Further, each of the U-shaped members 16 is connected to 3 of the reinforcing rods 15, whereby higher structural strength and impact resistance can be provided.

Further, the embedded reinforcement device 14 is made of 316L stainless steel, and the fixing ring 17 and the U-shaped member 16 may be integrally formed.

The corrosion resistance and long-term service performance of the stainless steel material can be ensured, the structural integrity can be improved through an integrated processing mode, and separation and fracture of the rigid-flexible material joint caused by long-term scouring and fatigue load are avoided.

Further, the stiffener 1 further comprises a barb device 3, the stiffener 1 and the bending limiter 2 are sequentially connected, the barb device comprises a steel body 32, a protrusion 31 positioned on the steel body 32 and a wedge-shaped block 33 arranged at the tail end, the protrusion 31 is used for being clamped into an opening of the side wall of the fan, and the wedge-shaped block 33 is used for being in wedge-shaped connection with the U-shaped piece 16.

Further, the barb device 3 is made of 316L stainless steel, so that corrosion resistance and long-term service performance are ensured.

Through bellied setting, can realize the firm fixed of barb device and fan, prevent that barb device from taking place the slippage under long-term washing and dynamic load effect. The wedge-shaped block is designed, so that the cross section of the connecting end is maximum, the cross section of the connecting end is gradually reduced along the length direction, the barb device and the reinforcing device are reliably connected, and meanwhile, the wedge-shaped block is gradually tightened under the action of dynamic load, so that the tensile stripping capacity is improved.

Further, a threaded hole 4 is formed in the wedge-shaped block 33, and the threaded hole 4 is connected with a bolt hole formed in the U-shaped piece 16 through a bolt 5.

At this time, the connection mode of barb device and intensity ware adopts wedge connection and bolted connection to combine together the mode, realizes dual fixed, further improves tensile taking-off ability.

Specifically, before installation, special lubricating oil is required to be smeared on the inner part of the U-shaped piece and the surface of the wedge-shaped block so as to ensure assembly precision and reduce friction damage. After installation, the wedge block is basically attached to the left end of the U-shaped piece, and the maximum gap at the right end is not more than 5mm, so that tight connection is ensured. When the wedge-shaped block and the U-shaped piece made of stainless steel are connected in a wedge-shaped mode in submarine service, steel structures of the wedge-shaped block and the U-shaped piece are gradually tightened after dislocation deformation, and meanwhile bolt locking is used for assisting, so that the pull-out risk caused by flushing and fatigue loading in the long-term service process is effectively reduced.

Claims

1. A bend limiter, comprising two bend limiter subunits (21) symmetrical about a central axis, the two bend limiter subunits (21) being detachably connected, a submarine cable (7) passing through a cavity (6) formed in the center of the two bend limiter subunits (21), each of the bend limiter subunits (21) comprising a male head (22), a female head (23), a connecting neck (24), an external locking portion (25) and a transition neck (26) arranged in sequence, a groove (27) being provided on the inner side of the female head (23), characterized in that: the male head (22) has a plurality of arc surfaces with different curvatures, the groove (27) also has arc surfaces with different curvatures, a side surface of the external locking portion (25) close to the male head (22) has a first angle relative to the central axis, a side surface of the female head (23) away from the male head (22) has a second angle relative to the central axis, the first angle and the second angle are substantially the same, The connecting neck (24) is composed of a plurality of circular arcs with different curvatures, and the transition neck (26) has a circular arc surface with a large curvature.

2. The bend limiter according to claim 1, characterized in that: a bolt hole (28) is provided on the bend limiter subunit (21), and two bend limiter subunits (21) are connected by bolts.

3. A submarine cable protection device, comprising a bend limiter as claimed in any one of claims 1 to 2, and a reinforcer (1) connected to the bend limiter, the reinforcer (1) comprising a connecting end (11), a connecting cylinder (12) and a connecting tail (13), characterized in that the shape and size of the connecting tail (13) are the same as those of the male head (22) of the bend limiter.

4. The submarine cable protection device according to claim 3 is characterized in that: the inner wall of the connecting end (11) is provided with an embedded reinforcement device (14), the embedded reinforcement device (14) comprises a reinforcement rod (15), a U-shaped part (16) and a fixing ring (17), the embedded reinforcement device (14) is embedded in the connecting end (11) through the reinforcement rod (15), the U-shaped part (16) is connected to the reinforcement rod (15), the U-shaped part (16) is evenly arranged along a ring relative to the central axis, the fixing ring (17) is arranged close to the inner wall of the connecting end (11), and the fixing ring (17) connects the U-shaped parts (16) arranged in a ring into a whole.

5. The submarine cable protection device according to claim 4, characterized in that: each of the U-shaped parts (16) is connected to three of the reinforcement rods (15), and/or the embedded reinforcement device is made of stainless steel, and/or the fixing ring (17) and the U-shaped part (16) are both integrally processed.

6. A submarine cable protection device according to any one of claims 4-5, characterized in that: the reinforcer (1) also includes a barb device (3), the barb device (3), the reinforcer (1) and the bend limiter (2) are connected in sequence, the barb device (3) includes a steel body (32), a protrusion (31) located on the steel body (32) and a wedge block (33) arranged at the tail end, and the wedge block (33) is used to perform a wedge connection with the U-shaped member (16).

7. The submarine cable protection device according to claim 6, characterized in that: a threaded hole (4) is provided on the wedge block (33), and the threaded hole (4) is connected to the bolt hole provided on the U-shaped member (16) through a bolt (5).

8. The submarine cable protection device according to claim 6, characterized in that the barb device (3) is made of stainless steel.

9. The submarine cable protection device according to any one of claims 3 to 5, characterized in that: the material of the bend limiter is polyurethane, and/or the material of the reinforcer (1) is polyurethane.