Large-angle wound composite pressure hull with positive gaussian curvature metal liner and processing method therefor

Abstract

A large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including a metal liner 4 and a carbon fiber layer 3 wrapped outside the metal liner. The metal liner is pro

Description

[0001] The present disclosure relates to pressure-resistant equipment, and particularly relates to a large-angle wound composite pressure hull with a positive Gaussian curvature metal liner and a processing method therefor. BACKGROUND

[0002] As a core component and buoyancy unit of a deep-sea submersible, a pressure hull plays an important role in ensuring the normal operation of non-pressure equipment, safeguarding health and safety of occupants, and providing positive buoyancy. The pressure hull usually takes the form of a body of revolution with a positive Gaussian curvature, including spherical hull, near-spherical hull, ellipsoidal hull, and egg-shaped hull. However, general metallic pressure hulls with positive Gaussian curvature have many problems, such as high specific weight, high sensitivity to defects, and low material utilization rate. With the advancement of composite material science, composite materials have been increasingly applied in pressure-resistant structures due to their superior properties. They effectively improve the load-bearing capacity of pressure hulls, and reduce weight of the pressure hulls and the submersibles, thereby realizing greater payload and longer operating range.

[0003] In the prior art, for example, the Chinese Patent Application No. CN202210335856.9 discloses a pressure hull for a deep-sea submersible made of a continuous carbon fiber-reinforced aluminum-based composite material, but it is only designed for a spherical hull, with a narrow range of application and an unspecified detailed manufacturing process. Another example is the Chinese Patent Application No. CN201910554969.6, which discloses a ply optimization design method for a pressure hull made of a composite material, including ply orientations such as ±30° and ±45°. However, for a pressure hull with a positive Gaussian curvature manufactured by wet filament winding, fiber slippage tends to occur during large-angle winding due to its unique structural shape, making it difficult to achieve the desired ply orientations. In summary, the prior art suffers from the following two problems:

[0004] 1. Traditional metal pressure hulls have a relatively high specific weight, low material utilization rate, and difficulty in processing, and they are prone to buckling under hydrostatic pressure.

[0005] 2. For the pressure hull with a positive Gaussian curvature manufactured by wet filament winding, fiber slippage will occur during large-angle winding, making it impossible to achieve the large-angle winding, which limits its ultimate load-bearing capacity and prevents it from meeting the needs of deep-sea operation at a great depth. SUMMARY

[0006] Objectives of the present disclosure: In view of the above deficiencies, the present disclosure provides a large-angle wound composite pressure hull with a positive Gaussian curvature metal liner.

[0007] The present disclosure further provides a processing method for the large-angle wound composite pressure hull with a positive Gaussian curvature metal liner.

[0008] Technical solution: In order to solve the above problems, the present disclosure provides a large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including a metal liner and a carbon fiber layer wrapped outside the metal liner; where the metal liner is provided with a plurality of holes that open outward, dowel pins are fixed in some or all of the holes, and the dowel pins extend through the carbon fiber layer from the metal liner.

[0009] Further, the other end of each hole on the metal liner is sealed and extends outward from the metal liner, and a depth h of each hole is denoted as: h = k±ts, k± G [1.5, 2]

[0010] where ts is a thickness of the metal liner.

[0011] Further, an outer profile of the metal liner is a surface of revolution with a positive Gaussian curvature, including an egg-shaped profile, an ellipsoidal profile and a spherical profile.

[0012] Further, when a profile equation / ?(%) of the outer profile of the metal liner that is an egg-shaped profile is expressed as follows: / 2 2n B R(x) = Ln+ixn+i — x2, n = 1.057(L / B)2372, SI =- = 0.69 Lj

[0013] where L denotes a major axis of the metal liner; B denotes a minor axis of the metal liner; and SI denotes an egg-shaped index of the metal liner.

[0014] Further, a total number of holes on the metal liner is SU-1) * h, where a generatrix arc length of the metal liner is evenly divided into I segments to obtain / -1 circular rings, such that a total of / -1 holes in a generatrix direction of the metal liner are formed, and a number of holes in an Ith circular ring of the metal liner is denoted as h, that is: ^R^d h~ d

[0015] where R(xt) denotes a circumferential radius of the ith circular ring of the metal liner, and d denotes a width of a fiber tow wound by wet winding.

[0016] Further, a length I of the dowel pin is denoted as: (J> 2 I = h + tc H——

[0017] where tc denotes a thickness of the carbon fiber layer, and denotes a diameter of the dowel pin.

[0018] Further, the pressure hull further includes a top end cap and a bottom end cap fixed at both ends of the metal liner, and the top end cap and the bottom end cap are respectively sealed to the carbon fiber layer with epoxy resin adhesive.

[0019] The present disclosure further provides a processing method for the large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including the following steps:

[0020] step 1: determining dimensions of a metal liner and then processing to obtain the metal liner;

[0021] step 2: determining winding angle and thickness of a carbon fiber layer;

[0022] step 3: determining positions on the metal liner where dowel pins are required: preliminarily determining positions on the metal liner where dowel pins are required according to surface friction force between the metal liner and the carbon fiber layer; simulating the winding of a fiber tow through a winding machine according to data of the metal liner and the carbon fiber layer, observing fiber slippage in real time and marking positions of fiber slippage, defining a circular ring with the hole closest to the positions of fiber slippage as a slippage zone; removing the metal liner, mounting dowel pins in the slippage zone, continuing to wind the fiber tow until the fiber layer reaches a preset thickness, and determining the positions on the metal liner where dowel pins are required;

[0023] step 4: inserting the dowel pins on the machined metal liner according to the determined positions on the metal liner where the dowel pins are required;

[0024] step 5: clamping the metal liner after being inserted with the dowel pins onto the winding machine, and winding the fiber tow according to the dimensions of the metal liner, as well as winding angle and thickness of the carbon fiber layer until the fiber layer reaches a preset thickness;

[0025] step 6: performing thermosetting curing after the model is wound;

[0026] step 7: removing excess structures, polishing and applying a waterproof coating; and

[0027] step 8: installing a top end cap and a bottom end cap, and sealing with epoxy resin adhesive.

[0028] Further, in the step 1, after determining dimensions of a metal liner, the metal liner is fabricated and obtained by 3D printing.

[0029] Further, in the step 3, when simulating the winding of a fiber tow through a winding machine, after the fiber tow completely wraps the metal liner for the first time and the fiber tow suffers fiber slippage on a surface of the carbon fiber layer, the winding process is ceased and the slippage positions are marked, the carbon fiber layer is removed, a circular ring with the hole closest to the slippage position on the metal liner is defined as the slippage zone, and the fiber tow is wound again after the dowel pins are mounted in the slippage zone.

[0030] Beneficial effects: Compared with the prior art, the present disclosure has the following obvious advantages:

[0031] 1. The large-angle wound composite pressure hull with a positive Gaussian curvature metal liner exhibits excellent geometric stability, enabling uniform distribution of external pressure under high-pressure conditions and avoiding local stress concentrations. In addition, it combines the advantages of composite materials, such as lightweight, fatigue resistance, and corrosion resistance, with high toughness and impact resistance of metal materials.

[0032] 2. By arranging the dowel pins on the surface of the metal liner with a positive Gaussian curvature, the present disclosure prevents fiber slippage during the large-angle winding process, the fiber tow is guided to be laid along a predetermined trajectory, thereby ensuring precise control of the winding angle and improving the winding quality.

[0033] 3. The dowel pins are arranged to penetrate the composite material, which significantly improves the fracture toughness and shear strength between the layers of composite material, and reduces the risk of interlayer delamination and failure, thereby improving the overall compressive performance and extending the service life of the structure.

[0034] 4. The dowel pins on the metal liner and the holes without dowel pins increase the bonding area between the metal liner and the composite material, resulting in a strong mechanical connection. The structure maintains the stability under long-term high-pressure conditions, and avoids the problems of aging and falling off commonly seen in the traditional bonding layers under extreme conditions, thereby extending he service life of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a front view and a sectional view of an egg-shaped pressure hull according to the present disclosure.

[0036] FIG. 2 is a schematic diagram of a profile equation curve of an egg-shaped pressure hull according to the present disclosure.

[0037] FIG. 3 is a front view and a sectional view of an egg-shaped metal liner according to the present disclosure.

[0038] FIG. 4 is a schematic diagram illustrating a connection among a metal liner, a fiber layer, and a dowel pin according to the present disclosure.

[0039] FIG. 5 is a structural schematic diagram of a dowel pin according to the present disclosure.

[0040] FIG. 6 is a schematic diagram illustrating force acting on a fiber tow on the metal liner according to the present disclosure.

[0041] FIG. 7 is a schematic diagram illustrating winding angle and ultimate load of a fiber tow in an egg-shaped pressure hull according to the present disclosure.

[0042] FIG. 8 is a schematic diagram of a winding trajectory of a fiber tow wrapped around a metal liner according to the present disclosure.

[0043] FIG. 9 is structural schematic diagrams of end caps according to the present disclosure.

[0044] FIG. 10 is a schematic flow diagram of processing according to the present disclosure.

[0045] FIG. 11 is a front view and a sectional view of an ellipsoidal pressure hull according to the present disclosure.

[0046] FIG. 12 is a schematic diagram of a profile equation curve of an ellipsoidal pressure hull according to the present disclosure.

[0047] FIG. 13 is a front view and a sectional view of an ellipsoidal metal liner according to the present disclosure.

[0048] FIG. 14 is a front view and a sectional view of a spherical pressure hull according to the present disclosure.

[0049] FIG. 15 is a schematic diagram of a profile equation curve of a spherical pressure hull according to the present disclosure.

[0050] FIG. 16 is a front view and a sectional view of a spherical metal liner according to the present disclosure. DETAILED DESCRIPTIONS OF THE EMBODIMENTS

[0051] Embodiment 1

[0052] As shown in FIG. 1, this embodiment provides a large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including a metal liner 4, a carbon fiber layer 3, a dowel pin 5, a top end cap 1, a bottom end cap 6 and an epoxy resin adhesive 2. An outer profile of the metal liner is a surface of revolution with a positive Gaussian curvature. In this embodiment, an egg-shaped profile is taken as an example, and the carbon fiber layer is formed by winding a fiber tow around the metal liner 4 at a large angle through wet winding.

[0053] FIG. 2 is a schematic diagram of a profile equation of the egg-shaped metal liner of the composite material. The profile equation of the egg-shaped metal liner is designed using an N-R equation, an egg-shaped curve equation, proposed by Narushin VG. and Romanov M.N. based on a Cartesian coordinate system. A generatrix profile equation is expressed as Equation (1): 2 2n R

[0054] R(x) x2, n = 1.057(L / B)2372, SI =^ = 0.69 (1)

[0055] where R(x) is the profile equation of the egg-shaped metal liner 4; L is a major axis of the egg-shaped metal liner 4; B is a minor axis of the egg-shaped metal liner 4; and SI is an egg-shaped index of the egg-shaped metal liner 4.

[0056] After a profile curve of the egg-shaped metal liner 4 is defined, a hole position for the dowel pin 5 on the metal liner 4 is designed. FIG. 3 is a structural schematic diagram of the egg-shaped metal liner 4. A generatrix arc length of the egg-shaped metal liner 4 is denoted as S, and the arc length S is expressed by Equation (2):

[0057] 5 = y / T+XR^x^dx (2)

[0058] where connecting rods are arranged at both ends of the egg-shaped metal liner 4, and a and b represent a starting horizontal coordinate and an ending horizontal coordinate of the egg-shaped metal liner 4;

[0059] the generatrix arc length of the egg-shaped metal liner 4 is evenly divided into I segments, such that a total of / -1 holes in a generatrix direction of the egg-shaped metal liner 4 are formed. An arc length between two adjacent holes is denoted as Sh and the arc length SI is expressed by Equation (3):

[0060] S} = 4V1+(«'W)2^, I = 1 2 3 ...... (3)

[0061] After a number of the holes in the generatrix direction of the egg-shaped metal liner 4 is determined, a number of in a circumferential direction of the egg-shaped metal liner 4 is designed. A width of the fiber tow wound by the wet winding is denoted as d, a circumferential radius of the egg-shaped metal liner 4 is denoted as R(xt), a circumferential length Ct of the egg-shaped metal liner 4 is expressed by Equation (4), and a number of holes jt in the circumferential direction is expressed by Equation (5):

[0062] Q = 2nR(xd (4)

[0063] = (5)

[0064] FIGs. 4 and 5 are a partial schematic diagram of the composite egg-shaped pressure hull, and a schematic diagram of the dowel pin. Depth and diameter of each hole on the egg-shaped metal liner 4 are denoted as h and ¢^, respectively, a thickness of the egg-shaped metal liner 4 is denoted as ts, and a thickness of the carbon fiber layer 3 is denoted as tc. Length and diameter of the dowel pin are denoted as I and <t>2, respectively. A relationship between the depth of the hole h and the thickness ts of the egg-shaped metal liner 4 is expressed by Equation (6):

[0065] h = k1ts, k± e [1.5, 2] (6)

[0066] A relationship between the length I of the dowel pin 5, and the thicknesses of the egg-shaped metal liner 4 and the carbon fiber layer 3 is expressed by Equation (7):

[0067] I = h + tc + y = k±ts + tc+^ (7)

[0068] The diameter <t>2 of the dowel pin 5 is slightly smaller than the diameter of the hole ¢^, as expressed in Equation (8):

[0069] ^2=k2^1, k2 e [0.8, 1) (8)

[0070] A force analysis is performed on the fiber tow wound around the egg-shaped metal liner 4, as shown in FIG. 6, where F denotes a fiber tension, fn denotes a normal force on the fiber, denotes a lateral force on the fiber, Rn denotes a normal radius of curvature (perpendicular to a surface), and Rg denotes a geodesic radius of curvature (parallel to the surface). The normal force on the fiber fn and the lateral force on the fiber are expressed by Equations (9) and (10), respectively:

[0071] fnRnA(p = 2Fsin fn = (9)

[0072] 2Fsin 2 ) (-10)

[0073] when the normal force fn on the fiber and the lateral force on the fiber do not satisfy the relationship of Equations (11) or (12), indicating that the fiber tow suffers slippage on the egg-shaped curved surface.

[0074] (11)

[0075] / M2< / z2 / n, (12)

[0076] In the above equations, andji2 denote surface friction coefficients of the egg-shaped metal liner 4 and the carbon fiber layer 3, respectively.

[0077] As shown in FIG. 7, geometric nonlinearity and material nonlinearity are taken into account, and a winding angle of the composite egg-shaped pressure hull ranges from ±50° to ±60°, an ultimate load at the range of the winding angle hull is much greater than an ultimate load at other winding angles. Therefore, ±50° to ±60° is also the winding angle range selected in this embodiment. Based on a preferred large-angle winding angle for increasing the ultimate load, a fiber slippage tends to occur on the egg-shaped curved surface. In order to meet the ultimate load requirements and ensure the reliability of wound fiber layers, the dowel pins need to be installed in a slippage zone to assist the fiber winding.

[0078] As shown in FIG. 8, geometric dimensions and shape of the egg-shaped metal liner 4 are inputted into winding software, winding parameters are then set, and a winding trajectory of the fiber tow on the egg-shaped metal liner 4 can be directly generated.

[0079] As shown in FIG. 9, sealing end caps at both ends are designed according to dimensions of the composite egg-shaped pressure hull after winding.

[0080] A processing method for the large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including the following steps:

[0081] Step 1: determining a profile equation of the metal liner 4 according to design requirements.

[0082] Step 2: designing a three-dimensional model of the metal liner 4 according to the profile equation determined in Step 1.

[0083] Step 3: manufacturing the metal liner 4 using 3D printing technology.

[0084] Step 4: determining winding angle and thickness of the carbon fiber layer 3 according to the design requirements.

[0085] Step 5: preliminarily calculating slippage positions of the fiber tow according to Equations (9)-(12), mounting the dowel pin 5 at each of the slippage positions, fixing the dowel pin 5 in holes of the metal liner 4 using adhesive, performing simulated winding to determine positions for insertion of the dowel pin on the metal liner 4; a specific process is as follows: geometrical parameters of the metal liner 4 and design parameters of the carbon fiber layer 3 are inputted into winding software, and the winding software generates the fiber winding trajectory and winding program.

[0086] The metal liner 4 is clamped onto a winding machine, and the winding program is inputted into the winding machine. The winding machine is started, and observation is performed to determine whether the fiber slippage occurs at any positions on the metal liner 4 where dowel pin 5 was not mounted yet.

[0087] When the slippage occurs, the winding process is ceased, the slippage positions are marked, and a circular ring with the hole closest to the slippage position on the metal liner is defined as the slippage zone. The metal liner 4 is removed, additional dowel pins 5 are mounted in the slippage zone, and the dowel pins 5 are fixed in the holes on the metal liner 4 with adhesive.

[0088] The metal liner 4 is re-clamped, and the winding machine is started to continue winding. The steps of winding, removal and insertion of dowel pin are repeated until the fiber tow completely wraps the metal liner 4.

[0089] After the fiber tow completely wraps the metal liner 4, a winding surface changes from a surface of the metal liner 4 to a surface of the carbon fiber layer 3. The change in the winding surface will lead to changes in a coefficient of friction, and it is still necessary to observe whether the fiber tow suffers fiber slippage on the surface of the carbon fiber layer 3 in a subsequent winding process.

[0090] When the fiber tow suffers fiber slippage on the surface of the carbon fiber layer 3, the winding process is ceased, and the slippage positions are marked. The model is disassembled, the carbon fiber layer 3 is removed at the same time, and a circular ring with the hole closest to the slippage position on the metal liner is defined as the slippage zone. Additional dowel pins 5 are mounted in the slippage zone, and the dowel pins 5 are fixed in the holes on the metal liner 4 with adhesive. The fiber tow is rewound until no fiber slippage occurs on the surface of the metal liner 4 and the surface of the carbon fiber layer 3.

[0091] Step 6: inserting the dowel pins on the machined metal liner according to the determined positions on the metal liner where the dowel pins are required.

[0092] Step 7: clamping the metal liner after being inserted with the dowel pins onto the winding machine, winding the fiber tow according to the dimensions of the metal liner, as well as winding angle and thickness of the carbon fiber layer until the fiber layer reaches a preset thickness.

[0093] Step 8: placing the model that has been wound and wrapped into an autoclave for thermosetting curing.

[0094] Step 9: cutting off the connecting rods at both ends of the metal liner 4 after thermosetting is completed.

[0095] Step 10: using sandpaper to polish an outer surface of the composite pressure hull with a positive Gaussian curvature, and applying a waterproof coating.

[0096] Step 11: installing a top end cap 1 and a bottom end cap 6, respectively, and sealing them using epoxy resin adhesive 2.

[0097] Embodiment 2:

[0098] As shown in FIGs. 11, 12 and 13, this embodiment provides a large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including a metal liner 4, a carbon fiber layer 3, a dowel pin 5, a top end cap 1, a bottom end cap 6 and an epoxy resin adhesive 2.

[0099] The design and processing method used in Embodiment 2 are identical to those in Embodiment 1, except for a change in the profile equation of the metal liner 4. FIG. 12 is a schematic diagram of a profile equation of an ellipsoidal metal liner of the composite material. The profile equation of the ellipsoidal metal liner is expressed by Equation (13):

[0100] R(x) =^^-%2 (13)

[0101] Embodiment 3:

[0102] As shown in FIGs. 14, 15 and 16, this embodiment provides a large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, including a metal liner 4, a carbon fiber layer 3, a dowel pin 5, a top end cap 1, a bottom end cap 6 and an epoxy resin adhesive 2.

[0103] The design and processing method used in Embodiment 3 are identical to those in Embodiment 1, except for a change in the profile equation of the metal liner 4. FIG. 15 is a schematic diagram of a profile equation of a spherical metal liner of the composite material. The profile equation of the spherical metal liner is expressed by Equation (14):

[0104] R(x) = I- — x2 (14)

Claims

What is claimed is:

1. A large-angle wound composite pressure hull with a positive Gaussian curvature metal liner, comprising a metal liner (4) and a carbon fiber layer (3) wrapped outside the metal liner (4); wherein the metal liner (4) is provided with a plurality of holes that open outward, dowel pins (5) are fixed in some or all of the holes, and the dowel pins (5) extend through the carbon fiber layer (3) from the metal liner (4).

2. The large-angle wound composite pressure hull with a positive Gaussian curvature metal liner according to claim 1, wherein an end of each hole on the metal liner (4) is sealed and extends outward from the metal liner (4), and a depth h of each hole is denoted as:h = k±ts, k± G [1.5, 2]wherein ts is a thickness of the metal liner.

3. The large-angle wound composite pressure hull with a positive Gaussian curvature metal liner according to claim 1, wherein an outer profile of the metal liner is a surface of revolution with the positive Gaussian curvature, and comprises an egg-shaped profile, an ellipsoidal profile or a spherical profile.

4. The large-angle wound composite pressure hull with a positive Gaussian curvature metal liner according to claim 3, wherein when the outer profile of the metal liner is the egg-shaped profile, a profile equation / ?(%) of the metal liner is expressed as follows:2 2n BR(x) = ^L^xim - x2, n = 1.057(L / B)2372, SI =- = 0.69wherein L denotes a major axis of the metal liner; B denotes a minor axis of the metal liner; and SI denotes an egg-shaped index of the metal liner.

5. The large-angle wound composite pressure hull with a positive Gaussian curvature metal liner according to claim 4, wherein a total number of holes on the metal liner is £( / -1) * ji, a generatrix arc length of the metal liner is evenly divided into I segments to obtain / -1 circular rings, a total of / -1 holes is formed in a generatrix direction of the metal liner, and a number of holes in an Ith circular ring of the metal liner is denoted as h, wherein. 271^(^)Ji~ dwherein R (x^ denotes a circumferential radius of the Ith circular ring of the metal liner, and d denotes a width of a fiber tow wound by wet winding.

6. The large-angle wound composite pressure hull with a positive Gaussian curvature metal12 06 25liner according to claim 2, wherein a length I of the dowel pin is denoted as:(J> 2I = h + tc H——wherein tc denotes a thickness of the carbon fiber layer, and denotes a diameter of the dowel pin.

7. The large-angle wound composite pressure hull with a positive Gaussian curvature metal liner according to claim 1, further comprising a top end cap (1) and a bottom end cap (6) fixed at both ends of the metal liner (4), and the top end cap (1) and the bottom end cap (6) are respectively sealed to the carbon fiber layer (3) with epoxy resin adhesive (2).

8. A processing method for the large-angle wound composite pressure hull with a positive Gaussian curvature metal liner according to any one of claims 1-7, comprising the following steps:step 1: determining dimensions of a metal liner and then processing to obtain the metal liner;step 2: determining winding angle and thickness of a carbon fiber layer;step 3: determining positions on the metal liner where dowel pins are required: preliminarily determining positions on the metal liner where dowel pins are required according to surface friction force between the metal liner and the carbon fiber layer; simulating the winding of a fiber tow through a winding machine according to data of the metal liner and the carbon fiber layer, observing fiber slippage in real time and marking positions of fiber slippage, defining a circular ring with the hole closest to the positions of fiber slippage as a slippage zone; removing the metal liner, mounting dowel pins in the slippage zone, continuing to wind the fiber tow until the fiber layer reaches a preset thickness, and determining the positions on the metal liner where dowel pins are required;step 4: inserting the dowel pins on the machined metal liner according to the determined positions on the metal liner where the dowel pins are required;step 5: clamping the metal liner after being inserted with the dowel pins onto the winding machine, and winding the fiber tow according to the dimensions of the metal liner, as well as winding angle and thickness of the carbon fiber layer until the fiber layer reaches a preset thickness;step 6: performing thermosetting curing after the model is wound;step 7: removing excess structures, polishing and applying a waterproof coating; andstep 8: installing a top end cap and a bottom end cap, and sealing with epoxy resin adhesive.

9. The processing method according to claim 8, wherein after determining dimensions of a metal liner in the step 1, the metal liner is fabricated and obtained by 3D printing.

10. The processing method according to claim 8, wherein in the step 3, when simulating the winding of a fiber tow through a winding machine, and after the fiber tow completely wraps the metal liner for the first time and the fiber tow suffers fiber slippage on a surface of the carbon fiberlayer, the winding process is ceased and the slippage positions are marked, the carbon fiber layer is removed, a circular ring with the hole closest to the slippage position on the metal liner is defined as a slippage zone, and the fiber tow is wound again after the dowel pins are mounted in the slippage zone.12 06 25IntellectualPropertyOfficeApplication GB2505860.3Search report under Section 17 of the Patents Act 1977Date search completed: 05 June 2025Claims searched: 1 to 10International classificationSubclass and subgroup Valid from B63B3 / 13 01 / 01 / 2006Field of searchWorldwide search of patent documents classified in the following areas of the IPC:B63B, B29DDatabases used in the preparation of this search report:SEARCH-PATENTDocuments considered to be relevantPatent literatureCategory Relevant claims Document of relevance A - CN 119348180 A (YANG), see the whole document. A - KR 101304260 B1 (KNOP), see the whole document.Intellectual Property Office is an operating name of the Patent Office www.gov.uk / ipo17Non-patent literatureCategory Relevant Document of relevance claimsCategoriesLetter or symbol Description X Document indicating lack of novelty or inventive step.Y Document indicating lack of inventive step, if combined with another document of the same category. & Member of the same patent family. A Document indicating technological background. P Document published on or after the priority date but before the fling date of the present application. E Earlier application published on or after the filing date of the present application.

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