An assemblable ductile buoyancy mooring chain of multiple lightweight material composites

Abstract

The present application provides a kind of multi-light material composite assemblable ductile buoyancy mooring chain.The single ring of the mooring chain is composed of polyimide resin core mold inner layer containing hollow beads and resin-based carbon fiber traction-resistant outer layer, and the core mold is composed of detachable single chain ring core mold and complete single chain ring core mold spaced jointing to ensure uninterrupted winding of carbon fiber on single ring body and realize multi-ring assembly extension.The detachable single chain ring is connected by mortise and tenon structure and embedded in dowel for fixing, and the complete single chain ring is a complete long circular ring structure.The proposed composite buoyancy mooring chain can be designed based on the size of core mold and carbon fiber layer, so that the overall density is less than the density of seawater, and it can be in floating state on the sea surface.

Description

Technical Field

[0001] This invention relates to the field of marine equipment technology, and in particular to an assemblable and extendable buoyancy mooring chain made of multiple lightweight composite materials. Background Technology

[0002] Mooring chains differ from ordinary anchor chains. They are chains of a certain length made up of multiple links, used to fix marine structures such as oil drilling platforms.

[0003] Traditional mooring chain links are manufactured using methods such as casting, forging, and welding, all using metallic materials. Cast steel mooring chain links offer high strength, rigidity, and long service life, making them suitable for mass production, but they have poor impact resistance. Forged mooring chain links have good impact toughness, but are expensive and have inconsistent quality. Except for mooring chain accessories, which are mostly forged, forged mooring chains have been largely phased out. Welded mooring chain links are made by bending and welding specific round steel materials; this process is advanced, simple, and low-cost. Therefore, cast steel and forged mooring chain links have gradually disappeared from the market, and welded mooring chain links have become the mainstream for large ships and offshore platforms. However, mooring chains made using these traditional methods have high material density and are susceptible to chemical and galvanic corrosion when submerged in seawater for extended periods. Furthermore, they require buoys for operation, have low portability during retrieval, and require significant additional work.

[0004] Therefore, there is an urgent need to design new structures using advanced materials to manufacture lightweight, high-strength, high-specific-strength, high-specific-stiffness, corrosion-resistant, and water-floating composite modular buoyancy mooring chains with good load-bearing capacity and fatigue life, reducing maintenance costs significantly, while also enabling disassembly and assembly. Summary of the Invention

[0005] To address the aforementioned technical problems, an assemblable and extendable buoyancy mooring chain composed of multiple lightweight materials is provided. The technical means employed in this invention are as follows:

[0006] A composite lightweight material assembly extendable buoyancy mooring chain is disclosed. Each link of the mooring chain consists of an inner layer of polyimide resin core mold containing hollow beads and an outer layer of resin-based carbon fiber with traction resistance. The core mold is composed of detachable single-link core molds and complete single-link core molds spliced ​​together with mortise and tenon joints to ensure that the carbon fiber is continuously wound around the single link and to achieve multi-link assembly and extension. The detachable single-link is composed of two C-shaped semi-rings connected by mortise and tenon joints and fixed with embedded tenon bars. The complete single-link is a complete elongated oval ring structure. The proposed composite material buoyancy mooring chain can be designed based on the core mold and carbon fiber layer dimensions to make the overall density less than that of seawater, so that it can float on the sea surface.

[0007] Furthermore, the detachable single-link core mold includes two C-shaped half-links. The two ends of the C-shaped half-links are respectively provided with cylindrical mortises and cylindrical tenons of matching specifications. A through hole is provided in the direction perpendicular to the mating interface. The through hole is interference-fitted with the tenon embedded therein and is assembled with the complete single-link core mold at intervals, thereby realizing multi-link assembly and can be extended indefinitely.

[0008] Furthermore, the carbon fiber traction-resistant outer layer is constructed by wet winding continuous carbon fiber filaments around the outside of the inner mandrel. Considering the different structures of the cylindrical and annular sections of the mooring chain links, and ensuring the fiber winding is not suspended, the azimuth angle θ in the greater circumference direction of the annular section and the rotational stretch radius of the annular section are determined. Core mold cross-sectional radius The angle between the fiber's start and end points on the cross section Fiber winding angle The numerical relationship between them.

[0009] Furthermore, the linear differential equation of the torus winding satisfies the following formula conditions:

[0010]

[0011] The winding inside the toroidal surface is a concave surface winding. During winding, the fiber will detach from the surface of the mandrel toroidal surface, resulting in a void. Therefore, the fiber winding must meet the following non-voiding condition:

[0012]

[0013] The equation for winding on a cylindrical surface satisfies the following formula conditions:

[0014]

[0015] Where s is the length of the cylinder.

[0016] Furthermore, the ratio of the hollow cross-sectional radius of the core mold to the cross-sectional radius of the core mold body is approximately 1:4. The carbon fiber structural layer is laid with a thickness of 4.8mm-5.5mm according to the aforementioned fiber winding angle α to ensure the strength of the main body while ensuring that its overall density is lower than that of seawater, so that the mooring chain can float on the sea surface.

[0017] This invention offers the following advantages: It employs a combination of low-density materials and a detachable mortise and tenon structure, enabling the mooring chain to be disassembled, shortened, and reassembled for extension. This significantly reduces the overall density of the mooring chain, allowing it to float on the sea surface and improving the ease of recovery for offshore platforms. Furthermore, the outer structural layer utilizes different carbon fiber bundle winding methods, meeting corrosion resistance requirements in marine environments while significantly improving the overall strength and traction resistance of the mooring chain. This invention provides a multi-lightweight composite, assemblable, extendable buoyancy mooring chain that effectively reduces the connection load on various offshore platforms, reduces the need for additional buoyancy aids such as buoys, improves the corrosion condition of submerged mooring chains, and extends their service life. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the mooring chain of the present invention;

[0020] Figure 2 This is a diagram showing the dimensions of a single-chain loop of the present invention;

[0021] Figure 3 This is a dimensional diagram of the detachable single-chain ring core mold tenon structure described in this invention;

[0022] Figure 4 This is a schematic diagram of the toroidal fiber winding angle described in this invention;

[0023] Figure 5 This is a schematic diagram of the cylindrical fiber winding angle described in this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention discloses an assemblable, extendable buoyancy mooring chain composed of multiple lightweight composite materials. Each single link consists of an inner core mold 15 and an outer traction-resistant layer 14 wound around the inner core mold. The inner core mold 15 comprises hollow polyimide resin beads, and the outer traction-resistant layer 14 comprises resin-based carbon fiber. This arrangement results in an overall mooring chain density lower than that of seawater. To improve the overall traction resistance, in a preferred embodiment, each single link includes a detachable single link core mold 1 and a complete single link core mold 2, assembled at intervals. To connect the two types of mooring chain core molds and lay the outer carbon fiber material, the inner core molds are connected by tenon and mortise structures 11 and 13, and fixed with embedded tenon bars 12, thereby improving structural stability. The single link is an elongated oval ring structure, and after the outer traction-resistant layer 14 is wound, the fibers of both the cylindrical and annular parts of the elongated oval ring structure are evenly covered.

[0026] In this embodiment, the external dimensions of the three-dimensional model of the mooring chain link are designed according to the national standard GB / T 20848-2017 for mooring chains. Figure 1 As shown, the chain link has a diameter of D, a length of L, and a width of W, where L≈6D and W≈3.35D. In this embodiment, the ring diameter D=38mm, the total length L=228mm, and the width W=127mm.

[0027] In this embodiment, the hollow beads are hollow microspheres, and the adhesive resin is selected as polyimide resin, thereby reducing weight and enhancing mechanical properties. Specifically, the hollow microsphere / polyimide resin composite material provided in this embodiment can achieve a minimum density of 0.7 g / cm³. 3 It has a water absorption rate of less than 3%, does not react with water, and is insoluble in water. Simultaneously, it possesses high mechanical strength, with a maximum compressive strength of 110 MPa, capable of withstanding high marine hydrostatic pressure, resistant to seawater corrosion, and its bulk elastic modulus is similar to or slightly higher than that of seawater. When the hollow microspheres account for 70% of the composition, its density is approximately 0.85 g / cm³. 3 It is still lower than the density of seawater (1.05 g / cm³). 3 The compressive strength is approximately 65 MPa. The core mold volume is approximately 280 cm³, and its weight is approximately 238 g. The hollow core mold volume is approximately 205 cm³. 3 The total volume of the core mold body and the hollow section is approximately 485 cm³. 3 .

[0028] Hollow microspheres have a much lower strength than resin and require a large filler volume, resulting in low compressive strength of the mandrel. To improve the filling rate of hollow microspheres while ensuring the strength of the mandrel, the matrix is ​​first reinforced and modified to increase the strength of the resin and reduce its viscosity, enabling a large proportion of hollow microspheres to be filled. Secondly, hollow microspheres of different diameters are selected and mixed in a certain proportion to increase the packing ratio of the hollow microspheres.

[0029] Specifically, the low-density hollow microsphere / polyimide resin core mold has a hollow structure, and the ratio of the cross-sectional radius of the hollow body to the cross-sectional radius of the core mold body is approximately 1:4, which satisfies the requirement that its overall density is lower than that of seawater, allowing the mooring chain to float on the sea surface.

[0030] The detachable mooring chain link mandrel includes two C-shaped half-links, each end of which is equipped with a cylindrical mortise and a matching cylindrical tenon. The mortise and tenon fit precisely into each other. Figure 2 As shown. The radius of the circular interface of the cylinder is... The distance from its center to its edge is The detachable high-strength mooring chain link mandrel has a sharp joint between the two C-shaped half-links, resulting in stress concentration. Furthermore, the effective cross-sectional area at the joint is small, making it a critical section. To ensure the critical sections at the tenon and mortise have the same strength, the cross-sectional areas of the two critical sections are designed to be equal, assuming the winding angle of the carbon fiber traction-resistant structural layer outside the critical section is the same, thus rationally distributing the structural strength at the tenon and mortise. In this embodiment, with an internal mandrel thickness of 2 mm, when the radius of the cylindrical mortise (tenon) is... And the distance from its center to its edge At that time, the dangerous cross-sectional area of ​​the tenon part =62.80mm 2 Dangerous cross-sectional area of ​​the mortise hole =62.60 mm 2 ,at this time This satisfies the same strength requirements. At this point, the stress on the internal core mold is almost negligible compared to the stress on the outer carbon fiber traction-resistant structural layer, achieving the expected effect of core mold support and carbon fiber layer stress.

[0031] like Figure 3 , Figure 4 As shown, to ensure that the entire chain ring core mold formed after the integration of the half-chain links has zero degrees of freedom in the spatial coordinate system, a through hole is provided in the direction perpendicular to the mating interface to reserve a position for inserting the tenon. The through hole and the tenon satisfy an interference fit. The through hole is rectangular with a side length of [missing information]. The length of the tenon is equal to the diameter of the mandrel. .

[0032] Specifically, unlike metals which can be freely shaped after melting and transitioning from a solid to a liquid state, carbon fiber workpieces require adjacent mooring chain links to be connected to form a closed loop before the carbon fiber bundles are continuously wound around the mandrel. Therefore, the mooring chain as a whole adopts a combination of detachable mooring chain links and integrated mooring chain links assembled at intervals. The number of mooring chain links is determined based on actual engineering requirements. n depending on L / l ( L For the total length of the mooring chain, l This is a value representing the length of a single mooring chain link. When the number of mooring chain links is 2... n When +1, use n A detachable mooring chain link and n +1 integrated mooring chain link, bringing the total number of mooring chain links to 2. n When using n A detachable mooring chain link and n One integrated mooring chain link. Using this combination method, with nearly half of the mooring chain links being integrated, can concentrate stress and further improve traction resistance.

[0033] In this embodiment, both the detachable high-strength mooring chain ring core mold and the integrated mooring chain ring core mold are made of hollow microsphere / polyimide resin composite material with high mechanical strength, high chemical resistance, and fatigue resistance. The hollow microspheres are uniformly dispersed in the polyimide resin matrix and can be processed by high-temperature extrusion molding to form a hollow core mold, which can provide support and sealing for the mooring chain ring.

[0034] To achieve traction resistance in the mooring chain, this embodiment employs a wet winding method to wind continuous carbon fiber filaments around the outer side of the inner mandrel, forming a pressure-resistant layer. Considering the different structures of the cylindrical and annular portions of the mooring chain rings, the rotational tensile radius of the annular portion is determined while ensuring the fiber winding does not leave gaps. Core mold cross-sectional radius The angle between the fiber's start and end points on the cross section Fiber winding angle The numerical relationship between them.

[0035] like Figure 5 As shown, the linear differential equation of a torus winding satisfies the following formula conditions:

[0036]

[0037] The winding inside the toroidal surface is a concave surface winding. During winding, the fiber will detach from the surface of the mandrel toroidal surface, resulting in a void. Therefore, the fiber winding must meet the following non-voiding condition:

[0038]

[0039] The equation for winding on a cylindrical surface satisfies the following formula conditions:

[0040]

[0041] Where s is the length of the cylinder.

[0042] In this embodiment, the calculated initial winding angle of the annular segment =72.3°, the mandrel can be wound on the cylindrical surface using a constant winding angle. To ensure that the strength of the critical section at the tenon is the same as that at the mortise, the winding angle... = 45°.

[0043] After winding 7-10 layers of carbon fiber to a thickness of approximately 1.4-2mm, it becomes difficult to guarantee both strength and stiffness. Increasing the number of layers increases the density. Therefore, during actual installation, the range of external force loads on the anchor chain is first investigated, and the required number of layers is calculated based on the range of external force and a safety factor. The safety factor can be 1.5 or 2. In a specific implementation, the carbon fiber structural layers are laid in 40-45 layers according to the aforementioned fiber winding angle α, approximately 4.8mm-5.5mm thick, ensuring the strength of the main body while ensuring that its average density after integration with the mandrel is less than the density of seawater.

[0044] In this embodiment, the density of the carbon fiber outer structure reinforcement layer is approximately 1.78 g / cm³. 3 It has a higher density than seawater (1.05 g / cm³). 3 The compressive strength is approximately 230 MPa. The carbon fiber structural layers are laid in 55 layers according to the aforementioned fiber winding angle α to ensure the strength of the main body while ensuring that its average density after integration with the mandrel is less than the density of seawater. Its thickness is approximately 3 mm, its mass is approximately 282.78 g, and its volume is approximately 157.10 cm³. 3 .

[0045] The total volume of the mooring chain is approximately 642.1 cm³. 3 The total weight is approximately 520.78g, and the average density is 0.81g / cm³. 3 It is less than the density of seawater by 1.05 g / cm³. 3 .

[0046] According to the national standard GB / T 20848-2017, an R3 grade ordinary unstacked mooring chain link is considered qualified if its maximum strain does not exceed 5% under a load of 745kN. Calculations show that the maximum deformation of the composite hollow mooring chain based on a mortise and tenon structure provided in this embodiment is 4.17% under a load of 745kN, meeting the requirements of the standard.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modular, extendable buoyancy mooring chain composed of multiple lightweight materials, characterized in that, Each link of the mooring chain consists of an inner layer of polyimide resin core mold containing hollow beads and an outer layer of resin-based carbon fiber with traction resistance. The core mold is composed of detachable single-link core molds and complete single-link core molds spliced ​​together using a tenon and mortise structure to ensure that the carbon fiber is continuously wound around the single link and to achieve multi-link assembly and extension. The detachable single-link is composed of two C-shaped half-rings connected by a tenon and mortise structure and fixed by embedded tenon bars. The complete single-link is a complete elongated oval ring structure. The proposed composite material buoyancy mooring chain can be designed based on the core mold and carbon fiber layer dimensions to make the overall density less than that of seawater, allowing it to float on the sea surface. The core mold is a hollow structure. The detachable single-link core mold includes two C-shaped half-links. The two ends of the C-shaped half-links are respectively provided with cylindrical mortises and cylindrical tenons of matching specifications. A through hole is provided in the direction perpendicular to the mating interface. The through hole is interference-fitted with the tenon inserted therein and is assembled with the complete single-link core mold at intervals, thereby realizing multi-link assembly and can be extended indefinitely. The carbon fiber traction-resistant outer layer is constructed by wet winding continuous carbon fiber filaments around the outside of the inner mandrel. Considering the different structures of the cylindrical and annular sections of the mooring chain links, the azimuth angle of the annular section in the greater circumference direction is determined while ensuring the fiber winding does not leave any gaps. θ Circular ring rotation stretch radius Core mold cross-sectional radius The angle between the fiber's start and end points on the cross section Fiber winding angle The numerical relationship between them; The linear differential equation of a torus satisfies the following formula conditions: The winding inside the toroidal surface is a concave surface winding. During winding, the fiber will detach from the surface of the mandrel toroidal surface, resulting in a void. Therefore, the fiber winding must meet the following non-voiding condition: The equation for winding on a cylindrical surface satisfies the following formula conditions: Where s is the length of the cylinder.

2. The assemblable, extendable buoyancy mooring chain of multiple lightweight composite materials according to claim 1, characterized in that, The ratio of the hollow cross-sectional radius to the cross-sectional radius of the core mold is approximately 1:

4. The carbon fiber structural layers are arranged according to the aforementioned fiber winding angle. Laying a 4.8mm-5.5mm layer ensures the strength of the main body while maintaining an overall density lower than that of seawater, allowing the mooring chain to float on the sea surface.

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