Three-dimensional woven ultra-lightweight primary load bearing members and methods of making the same

Abstract

The present application relates to the technical field of three-dimensional braided carbon fiber design, molding and manufacturing, and provides a three-dimensional braided ultra-light main load-bearing component and a manufacturing method thereof, wherein the manufacturing method of the three-dimensional braided ultra-light main load-bearing component comprises the following steps: assembling a support body, a first TC4 titanium alloy joint and a second TC4 titanium alloy joint to form a tubular body; the first TC4 titanium alloy joint and the second TC4 titanium alloy joint each comprise a joint body, and the entire outer surface of the joint body is integrally provided with a protruding portion; at least one of the first TC4 titanium alloy joint and the second TC4 titanium alloy joint further comprises a connecting portion, and the connecting portion is integrally arranged on the side of the joint body away from the support body; carbon fiber yarns are braided on the outer surface of the tubular body in a three-dimensional five-direction braiding manner to form a carbon fiber yarn braiding layer, and the carbon fiber yarn braiding layer covers the protruding portion. In this way, the load-carrying capacity is more excellent, the structural efficiency is higher, the specific strength is larger, and the impact resistance is better.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of three-dimensional woven carbon fiber design, forming and manufacturing, in particular to a three-dimensional woven ultra-light main load-bearing component and a manufacturing method thereof. BACKGROUND

[0002] In the field of aerospace and national defense science and technology, the requirements for material performance are extremely strict, and materials with light weight, high strength and excellent mechanical properties are the key to ensuring the performance and reliability of equipment. Carbon fiber composite materials have been widely used in this field due to their excellent mechanical properties, and are often used as load-bearing structural materials.

[0003] At present, common connection forms of carbon fiber composite material load-bearing structures include bonding, mechanical connection, riveting, hybrid connection and pre-embedded connection. However, current connection designs mainly focus on two-dimensional composite material connection modes. Two-dimensional composite materials as main load-bearing structures have many defects that are difficult to overcome and cannot meet the strict requirements of light weight and high strength. For example, two-dimensional composite materials have poor out-of-plane performance, and their ability to resist deformation and damage is limited when subjected to loads perpendicular to the material plane. Under the action of thermal and mechanical cycles, serious delamination occurs in the material, which significantly reduces the overall strength and stability of the structure. And when in the near space extreme environment (temperature below -110℃), the micro interface of two-dimensional composite materials becomes very weak and is prone to damage, which affects the performance and safety of the entire structure. SUMMARY

[0004] The present application provides a three-dimensional woven ultra-light main load-bearing component and a manufacturing method thereof to solve the problem that two-dimensional composite materials cannot meet the requirements of light weight, high strength and high toughness in the prior art.

[0005] The present application provides a manufacturing method of a three-dimensional woven ultra-light main load-bearing component, comprising:

[0006] The support body, the first TC4 titanium alloy joint and the second TC4 titanium alloy joint are assembled to form a tubular body; wherein the first TC4 titanium alloy joint and the second TC4 titanium alloy joint are arranged at opposite ends of the support body; each of the first TC4 titanium alloy joint and the second TC4 titanium alloy joint comprises a joint body, the entire outer surface of the joint body is integrally provided with a protruding portion, the joint body is a cylinder, the included angle between the center line of the upper and lower end faces of the cylinder and the edge line of the cylinder is α, and the α is 0.3-0.7°; wherein at least one of the first TC4 titanium alloy joint and the second TC4 titanium alloy joint further comprises a connecting portion, the connecting portion is integrally arranged on the side of the joint body away from the support body, and the connecting portion is adapted to be connected with an external component;

[0007] Carbon fiber yarns are woven into the outer surface of the tubular body using a three-dimensional five-directional weaving method to form a carbon fiber yarn woven layer, which covers the protrusion. The outer diameter of the support is D1, the outer diameters of the first TC4 titanium alloy connector and the second TC4 titanium alloy connector are both D2, and the length of the protrusion is D3. D1 is greater than D2, and D3 is greater than the difference between D1 and D2.

[0008] According to the present invention, a method for manufacturing a three-dimensional braided ultralight main load-bearing component, wherein carbon fiber yarn is braided onto the outer surface of the tubular body using a three-dimensional five-directional braiding method, comprising:

[0009] Carbon fiber yarns are woven into the outer surfaces of the connecting part, the joint body, and the support body using a three-dimensional five-directional weaving method, wherein the length of the carbon fiber yarn woven layer on the connecting part is 3% to 5% of the length of the connecting part.

[0010] A method for manufacturing a three-dimensional braided ultralight main load-bearing component according to the present invention further includes:

[0011] Aramid fibers are spirally wound around the carbon fiber yarn braided layer corresponding to the outer surfaces of the first TC4 titanium alloy joint and the second TC4 titanium alloy joint to form a tough protective layer.

[0012] According to a method for manufacturing a three-dimensional braided ultralight main load-bearing component provided by the present invention, before assembling the support body, the first TC4 titanium alloy joint, and the second TC4 titanium alloy joint, the method further includes:

[0013] The outer surfaces of the first TC4 titanium alloy connector and the second TC4 titanium alloy connector are sandblasted.

[0014] According to a method for manufacturing a three-dimensional braided ultralight main load-bearing component provided by the present invention, the outer diameter of the connecting part is equal to the outer diameter of the joint body, and longitudinal and transverse pits are provided on the outer surface of the connecting part.

[0015] The outer diameter of the connecting part is smaller than the outer diameter of the connector body, and an external thread is provided on the outer surface of the connecting part; or...

[0016] The outer diameter of the connecting part is equal to the outer diameter of the connector body, and the connecting part is provided with internal threads; or...

[0017] The connecting part is provided with mounting holes; or...

[0018] The outer surface of the connecting part is provided with a plurality of block-shaped bodies arranged at intervals along the circumferential direction of the connecting part; or...

[0019] The connecting part is provided with a connecting flange.

[0020] According to a method for manufacturing a three-dimensional woven ultralight main load-bearing component provided by the present invention, one of the support body and the connector body is provided with a slot, and the other is provided with a pin that mates with the slot. The support body and the connector body are connected and engaged through the slot and the pin.

[0021] According to a method for manufacturing a three-dimensional braided ultralight main load-bearing component provided by the present invention, multiple sets of protrusions are arranged at intervals along the length direction of the joint body, and multiple protrusions in each set are arranged at intervals along the circumferential direction of the joint body; wherein, each protrusion in two adjacent sets of protrusions is staggered.

[0022] According to a method for manufacturing a three-dimensional woven ultralight main load-bearing component provided by the present invention, the protrusion includes a pointed needle and a needle cap disposed at the head of the pointed needle; or,

[0023] The protrusion includes a first needle and a second needle, the length of the first needle being greater than the length of the second needle. The first needle group and the second needle group are spaced apart along the length direction of the connector body; wherein the length of the first needle is twice the length of the second needle, and the length of the first needle is greater than or equal to 1.4 mm; or...

[0024] The protrusion includes a pointed needle and a first hook and a second hook disposed at the head of the pointed needle, wherein the radius of the first hook and the second hook is 0.3~0.6mm; or,

[0025] The protrusion includes a first needle and a second needle. The second needle includes a needle and a first hook and a second hook disposed at the head of the needle. The radius of the first hook and the second hook is 0.3~0.6mm. The first needle group and the second needle group are arranged at intervals along the length direction of the connector body.

[0026] According to a method for manufacturing a three-dimensional braided ultralight main load-bearing component provided by the present invention, the sum of the lengths of the two joint bodies and the length of the support body satisfy the following relationship:

[0027] 0.1 L ≤ L 1+ L 2≤0.8 L ;

[0028] The lengths of the two connector bodies are respectively L 1 and L 2. The length of the support body is L .

[0029] The present invention also provides a three-dimensional braided ultralight main load-bearing component, which is manufactured using the above-described manufacturing method for the three-dimensional braided ultralight main load-bearing component.

[0030] The three-dimensional braided ultralight main load-bearing component and its manufacturing method provided by this invention have superior load-bearing capacity, higher structural efficiency, greater specific strength, and better impact resistance compared to two-dimensional winding and pre-embedded connection. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this 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 this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a flowchart of the manufacturing method of the three-dimensional braided ultralight main load-bearing component provided by the present invention.

[0033] Figure 2 This is one of the structural schematic diagrams of the three-dimensional woven ultralight main load-bearing component provided by the present invention.

[0034] Figure 3 This is the second structural schematic diagram of the three-dimensional woven ultralight main load-bearing component provided by the present invention.

[0035] Figure 4 This is the third structural schematic diagram of the three-dimensional woven ultralight main load-bearing component provided by the present invention.

[0036] Figure 5 This is the fourth structural schematic diagram of the three-dimensional woven ultralight main load-bearing component provided by the present invention.

[0037] Figure 6 This is the fifth structural schematic diagram of the three-dimensional woven ultralight main load-bearing component provided by the present invention.

[0038] Figure 7 This is one of the structural schematic diagrams of the first TC4 titanium alloy connector provided by the present invention.

[0039] Figure 8 This is the second structural schematic diagram of the first TC4 titanium alloy connector provided by the present invention.

[0040] Figure 9 This is the third structural schematic diagram of the first TC4 titanium alloy connector provided by the present invention.

[0041] Figure 10 This is the fourth structural schematic diagram of the first TC4 titanium alloy connector provided by the present invention.

[0042] Figure 11 This is the fifth structural schematic diagram of the first TC4 titanium alloy connector provided by the present invention.

[0043] Figure 12 This is one of the structural schematic diagrams of the connector body provided by the present invention.

[0044] Figure 13 yes Figure 12 A sectional view.

[0045] Figure 14 yes Figure 12 Top view.

[0046] Figure 15 This is the second structural schematic diagram of the connector body provided by the present invention.

[0047] Figure 16 yes Figure 15 A sectional view.

[0048] Figure 17 yes Figure 15 Top view.

[0049] Figure 18 This is the third structural schematic diagram of the connector body provided by the present invention.

[0050] Figure 19 yes Figure 18 A sectional view.

[0051] Figure 20 yes Figure 18 Top view.

[0052] Figure 21 This is the fourth structural schematic diagram of the connector body provided by the present invention.

[0053] Figure 22 yes Figure 21 A sectional view.

[0054] Figure 23 yes Figure 21 Top view.

[0055] Figure 24 This is the fifth structural schematic diagram of the connector body provided by the present invention.

[0056] Figure 25 yes Figure 24 A sectional view.

[0057] Figure 26 yes Figure 24 Top view.

[0058] Figure label:

[0059] 1. Support body; 2. First TC4 titanium alloy connector; 21. Connector body; 22. Protrusion; 23. Connecting part; 24. Sandblasted layer; 3. Second TC4 titanium alloy connector; 4. Carbon fiber yarn braided layer. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0061] Three-dimensional braided composite materials exhibit multiple advantages compared to traditional laminated or two-dimensional wound composite materials:

[0062] 1. Significant structural integrity

[0063] No risk of delamination: Traditional laminated materials are prone to delamination failure due to interlayer stress, while three-dimensional weaving forms an overall network through the interweaving of yarns in three-dimensional space, fundamentally eliminating the interlayer interface and greatly improving the resistance to delamination.

[0064] High damage tolerance: The fibers are continuously distributed in three-dimensional space, making it difficult for local damage to propagate and significantly enhancing the toughness of the material.

[0065] 2. Excellent mechanical properties

[0066] Multi-directional load-bearing capacity: The fibers are arranged in multiple directions (X, Y, Z) (or even more directions or at different angles to the XYZ directions), and can simultaneously withstand multi-axial loads such as tension, shear, compression, bending and torsion, with low anisotropy.

[0067] High impact resistance: The three-dimensional structure effectively absorbs impact energy, preventing penetrating damage under ballistic or low-velocity impacts (such as aerospace bulletproof components).

[0068] High specific strength / specific stiffness: Through optimized weaving design, a perfect combination of ultra-lightweight with high strength, high toughness and high modulus is achieved.

[0069] 3. High adaptability to complex shapes

[0070] Direct molding of irregular structures: Complex curved surfaces or irregular components (such as turbine blades and irregular joints) can be woven in one go, reducing subsequent processing and connection points, and reducing weight and stress concentration risks.

[0071] Flexible design: By adjusting weaving parameters (such as configuration, fiber content, and weaving angle), local properties can be customized to meet the needs of gradient materials.

[0072] 4. Excellent environmental adaptability

[0073] Outstanding fatigue resistance: The three-dimensional structure delays crack initiation and propagation, and significantly extends service life under cyclic loading (such as helicopter rotor components).

[0074] High temperature / corrosion resistant: compatible with ceramic fiber (such as SiC) or high temperature resin matrix, suitable for extreme environments (such as hot end components of engines, cold end components at ultra-low temperatures).

[0075] 5. Outstanding functional integration capabilities

[0076] Multifunctional integration: During the weaving process, channels can be reserved or sensors and conductive fibers can be embedded to achieve structure-function integration (such as self-monitoring, electromagnetic shielding, thermal management, etc.).

[0077] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the manufacturing method of the three-dimensional braided ultralight main load-bearing component according to an embodiment of the present invention includes:

[0078] Step 100: Assemble the support body 1, the first TC4 titanium alloy connector 2, and the second TC4 titanium alloy connector 3 to form a tubular body; wherein the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 are respectively located at opposite ends of the support body 1; the outer surfaces of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 are sandblasted; multiple protrusions 22 are integrally provided on the outer surfaces of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3.

[0079] Among them, the support body 1 can be made of PMI foam, and the density of the support body 1 is ρ, where ρ≥80kg / m³. 3 Support 1 can be a cylindrical structural component.

[0080] PMI foam is a cross-linked rigid foam material with a closed-cell structure of over 99%, isotropic, and with uniformly cross-linked pore walls, giving it outstanding structural stability and excellent mechanical properties. It possesses high specific strength and high specific modulus, making it superior in performance among various foam materials, while also exhibiting good compression creep resistance. Its heat distortion temperature is 180–240℃, meeting the requirements for medium- and high-temperature, high-pressure curing and prepreg processes.

[0081] The first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 are made of TC4 titanium alloy material. They are precision forged and machined to ensure their dimensional accuracy and surface quality. At the same time, the outer surface of the titanium alloy connector is sandblasted to form a sandblasted layer 24, thereby enhancing the bonding ability with carbon fiber yarn.

[0082] In other words, the support 1, the first TC4 titanium alloy connector 2, and the second TC4 titanium alloy connector 3 are all prefabricated parts, and different types of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 can be selected according to actual needs.

[0083] Step 200: Carbon fiber yarn is woven onto the outer surface of the tubular body using a three-dimensional five-directional weaving method to form a carbon fiber yarn woven layer 4. The carbon fiber yarn woven layer 4 covers the protrusion 22. That is, the carbon fiber yarn woven layer 4 is formed on the support body 1, the first TC4 titanium alloy joint 2, and the second TC4 titanium alloy joint 3, and can ensure that the protrusion 22 located on the first TC4 titanium alloy joint 2 and the second TC4 titanium alloy joint 3 is not exposed.

[0084] The outer diameter of the support 1 is D1, the outer diameter of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 is D2, and the length of the protrusion 22 is D3; wherein, D1 is greater than D2, and D3 is greater than the difference between D1 and D2.

[0085] The following is a detailed explanation of three-dimensional five-directional weaving:

[0086] 1. Five-dimensional definition

[0087] Based on three-dimensional four-way weaving, the Z direction is introduced from the X, Y and Z directions. The weaving angle of the four-way weaving yarn is ±θ, where θ is usually the angle with the Z direction. The value of θ ranges from 5° to 45°, forming a yarn interlacing network in five directions.

[0088] 2. Structural Features

[0089] Integrity: The yarn runs continuously through three-dimensional space without layering or interfaces, avoiding the risk of debonding in traditional laminated structures.

[0090] Isotropic: The introduction of four-directional yarns makes the material's performance more balanced in the plane (XY) and in spatial structure, reducing directional dependence.

[0091] High fiber volume content: By optimizing the weaving path, the fiber volume fraction can reach 55%~60%, which is significantly higher than the traditional layup process (about 50%).

[0092] It should be noted that the thickness, D1, D2, and D3 of the carbon fiber yarn braided layer 4 satisfy the following relationship:

[0093] T = k1 × (D1 - D2) / D3 + k2;

[0094] Where 0.5≤k1≤1.5, 0.7≤k2≤1.5, k1 is a constant determined based on the properties of carbon fiber, k2 is a constant determined based on actual working conditions, and T is the thickness of the carbon fiber yarn braided layer 4.

[0095] It should be noted that the properties of carbon fiber generally include fiber volume content and porosity. In actual working conditions, load-bearing capacity (kN), specific strength (MPa / (g / cm³)), and impact overload resistance (g) are generally considered.

[0096] It is particularly important to note that the ultralight main load-bearing component adopts a three-dimensional five-directional woven structure in order to obtain greater axial load-bearing strength. The fiber volume content is controlled within the range of 50% to 60%, and the porosity is controlled below 6%.

[0097] Understandably, the weaving angle of the three-dimensional five-way braiding can be effectively adjusted according to the actual operating conditions. If the axial load-bearing capacity of the braided structure is required to be high, the weaving angle β1 of the carbon fiber yarn (β1∈(10º~25º)) should be controlled within a small range, and the axial carbon fiber volume content should be increased as much as possible. If the shear or torsional resistance of the braided structure is required to be high, the weaving angle β2 of the carbon fiber yarn (β2∈(25º~55º)) should be controlled within a large range, and the carbon fiber volume content of the four-way yarn should be increased as much as possible.

[0098] Furthermore, in optional embodiments, the method for manufacturing the three-dimensional braided ultralight main load-bearing component may further include:

[0099] Aramid fibers are spirally wound onto the outer surface of the carbon fiber yarn braided layer 4, corresponding to the first TC4 titanium alloy joint 2 and the second TC4 titanium alloy joint 3, to form a tough protective layer.

[0100] It should be noted that, in response to the stress concentration and brittle fracture risk in the areas of the first TC4 titanium alloy joint 2 and the second TC4 titanium alloy joint 3, a local gradient protective layer is formed by spirally winding aramid fibers. Without increasing the weight, the impact resistance is improved by ≥120% and the toughness is enhanced by ≥30%.

[0101] In practical applications, after the tough protective layer is formed, the three-dimensional woven ultralight main load-bearing component of this invention is finally obtained by vacuum-assisted low-pressure resin infiltration and integrated curing technology.

[0102] As shown in Table 1, the three-dimensional braided ultralight main load-bearing component of the present invention has superior load-bearing capacity, higher structural efficiency, greater specific strength, and better impact resistance. In other words, its mechanical properties are significantly improved compared to two-dimensional winding pre-embedded connections.

[0103] Table 1 Comparison of Mechanical Properties

[0104]

[0105] Furthermore, in this embodiment of the invention, the contact between the first TC4 titanium alloy joint 2 and the second TC4 titanium alloy joint 3 and the braided yarn fully considers the electrochemical interaction between the metal and the carbon fiber. High-strength and high-toughness TC4 titanium alloy joints are selected and integrally cured with the carbon fiber yarn braided layer. Generally speaking, combining aluminum alloys with carbon fibers carries significant risks, as electrochemical reactions can occur, leading to a substantial reduction in structural lifespan. Moreover, this is a restricted process in the aerospace field. This embodiment of the invention uses a combination of TC4 titanium alloy and three-dimensional braided carbon fiber, completely avoiding the problems caused by the electrochemical reaction between traditional metals and carbon fibers, and solving the reliability problem for ultra-long-term service. On the one hand, it achieves ultra-lightweight, high-strength, and high-toughness application functions; on the other hand, it avoids the electrochemical corrosion of yarn with traditional hard aluminum, stainless steel, etc., and provides key technical support for the ultra-lightweight main load-bearing components to serve for ultra-long periods.

[0106] In optional embodiments, such as Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 As shown, each of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 includes a connector body 21, and a protrusion 22 is integrally disposed on the entire outer surface of the connector body 21.

[0107] Among them, at least one of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 further includes a connecting part 23, which is integrally disposed on the side of the connector body 21 away from the support body 1, and the connecting part 23 is adapted to cooperate with external components for connection.

[0108] It should be noted that the first TC4 titanium alloy connector 2 may include a connecting part 23 and a connector body 21, or it may only include the connector body 21. Similarly, the second TC4 titanium alloy connector 3 may include a connecting part 23 and a connector body 21, or it may only include the connector body 21. Whether the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 are provided with a connecting part 23 can be selected according to the application scenario of the three-dimensional braided ultralight main load-bearing component, and no specific limitation is made here.

[0109] In optional embodiments, such as Figure 7As shown, the outer diameter of the connecting portion 23 is equal to the outer diameter of the connector body 21, and longitudinal and transverse recesses are provided on the outer surface of the connecting portion 23. For example, multiple recesses are evenly distributed on the outer surface of the connecting portion 23, and the recesses can be circular in shape, arranged evenly along the circumference of the connecting portion 23. It should be noted that the material of the connecting portion 23 is the same as that of the connector body 21, and the shape of the connecting portion 23 is the same as that of the connector body 21.

[0110] like Figure 8 As shown, the outer diameter of the connecting part 23 is smaller than the outer diameter of the connector body 21, and an external thread is provided on the outer surface of the connecting part 23. It should be noted that the material of the connecting part 23 is the same as that of the connector body 21, and the shape of the connecting part 23 is the same as that of the connector body 21. For example, both the connector body 21 and the connecting part 23 are cylinders.

[0111] Alternatively, the outer diameter of the connecting part 23 is equal to the outer diameter of the connector body 21, and the connecting part 23 has internal threads. It should be noted that the material of the connecting part 23 is the same as that of the connector body 21, and the shape of the connecting part 23 is the same as that of the connector body 21. For example, both the connector body 21 and the connecting part 23 are cylinders. The connecting part 23 has an internal mounting hole, and the wall of the mounting hole has internal threads.

[0112] like Figure 9 As shown, the connecting part 23 is provided with a mounting hole. It should be noted that the material of the connecting part 23 is the same as that of the connector body 21. The connector body 21 can be a cylinder, while the connecting part 23 can be a flat body. The connecting part 23 is provided with a circular mounting hole.

[0113] like Figure 10 As shown, a plurality of block-shaped bodies are arranged at intervals along the circumferential direction of the connecting part 23 on its outer surface. It should be noted that the material of the connecting part 23 is the same as that of the connector body 21. The connector body 21 can be a cylinder, while the connecting part 23 can be a cylinder with a circular cross-section. Furthermore, the cross-sectional area of ​​the cylinder gradually increases along the direction away from the connector body 21. A plurality of block-shaped bodies are arranged at intervals along the circumferential direction of the connecting part 23, and the number of block-shaped bodies can be four.

[0114] like Figure 11 As shown, the connecting part 23 is provided with a connecting flange. It should be noted that the material of the connecting part 23 is the same as that of the connector body 21. The connector body 21 can be a cylinder, and the connecting part 23 can be a cylinder. The outer diameter of the connecting part 23 is equal to the outer diameter of the connector body 21, and the connecting flange is fitted on the connecting part 23.

[0115] In practical applications, based on the load-bearing capacity of the three-dimensional braided ultralight main load-bearing component and the actual engineering requirements, the configurations of the first TC4 titanium alloy joint 2 and the second TC4 titanium alloy joint 3 are specifically designed, and the outer surfaces of the connecting part 23 and the joint body 21 are sandblasted.

[0116] In an optional embodiment, where at least one of the first TC4 titanium alloy connector 2 and the second TC4 titanium alloy connector 3 further includes a connecting portion 23, the carbon fiber yarn is woven onto the outer surface of the tubular body using a three-dimensional five-directional braiding method, including:

[0117] Carbon fiber yarn is woven into the outer surface of the connector 23, the connector body 21 and the support 1 using a three-dimensional five-directional weaving method. The length of the carbon fiber yarn woven layer 4 on the connector 23 is 3% to 5% of the length of the connector 23.

[0118] In other words, when the first TC4 titanium alloy connector 2 includes a connecting portion 23, carbon fiber yarn is woven into the connecting portion 23 of the first TC4 titanium alloy connector 2, the connector body 21 of the first TC4 titanium alloy connector 2, the connector body 21 of the second TC4 titanium alloy connector 3, and the outer surface of the support 1 using a three-dimensional five-directional braiding method. The length of the carbon fiber yarn braided layer 4 on the connecting portion 23 of the first TC4 titanium alloy connector 2 is 3% to 5% of the length of the connecting portion 23. For example, the length of the carbon fiber yarn braided layer 4 on the connecting portion 23 of the first TC4 titanium alloy connector 2 is 3%, 4%, or 5% of the length of the connecting portion 23.

[0119] In an optional embodiment, one of the support body 1 and the connector body 21 is provided with a slot, and the other is provided with a pin that mates with the slot. The support body 1 and the connector body 21 are connected and engaged through the slot and the pin.

[0120] For example, the support body 1 is provided with a pin, and the connector body 21 is provided with a slot. Through the insertion and engagement of the slot and the pin, the connection between the support body 1 and the connector body 21 is more secure, which can effectively prevent loosening or falling off during the weaving process. In addition, the structural design of the slot and the pin simplifies the assembly process and reduces the assembly difficulty.

[0121] In optional embodiments, such as Figure 2 and Figure 3 As shown, the connector body 21 is a cylinder, and the angle between the line connecting the centers of the upper and lower end faces of the cylinder and the edge line of the cylinder is α, where α is 0.3~0.7°.

[0122] It should be noted that the connector body 21 has a large-diameter end and a small-diameter end, wherein the end closer to the support body 1 is the large-diameter end, and the end farther away from the support body 1 is the small-diameter end. α can be 0.3°, 0.4°, 0.5°, 0.6°, or 0.7°.

[0123] Understandably, the tapered design on the end face of the cylinder is primarily intended to effectively enhance its axial tensile load-bearing capacity.

[0124] In an optional embodiment, multiple sets of protrusions 22 are arranged sequentially at intervals along the length direction of the connector body 21, and multiple protrusions 22 in each set of protrusions 22 are arranged sequentially at intervals along the circumferential direction (C-axis) of the connector body 21; wherein, each protrusion 22 in two adjacent sets of protrusions 22 is staggered.

[0125] It should be noted that M groups of protrusions 22 (M≥10) are arranged at intervals along the length direction (L-axis) of the connector body 21, with each group containing N protrusions 22 (N≥16). The distance between two adjacent groups of protrusions 22 along the length direction of the connector body 21 is H, where H≥5mm. The protrusions 22 in two adjacent groups are staggered bidirectionally along the L-axis and C-axis, forming a "spiral-interlaced" structure. The stagger angle θ1 is less than or equal to 11.25° (relative to the axial direction), and the stagger distance ΔL = 0.2D2 ~ 0.5D2 (D2 is the outer diameter of the connector body 21).

[0126] In optional embodiments, such as Figure 12 , Figure 13 and Figure 14 As shown, the protrusion 22 includes a needle. Exemplarily, the needle includes a cylindrical root and a tapered tip, with an included angle θ2 between adjacent needles in the circumferential direction of the connector body 21, where θ2 ≤ 22.5º. Furthermore, the length of the needle is greater than or equal to 3.0 mm. Additionally, the outer diameter of the cylindrical root of the needle is not less than 2 mm.

[0127] like Figure 15 , Figure 16 and Figure 17 As shown, the protrusion 22 includes a first needle and a second needle, the length of the first needle being greater than the length of the second needle. The first needle group and the second needle group are spaced apart along the length direction of the connector body 21. The length of the first needle is twice the length of the second needle, and the length of the first needle is greater than or equal to 1.4 mm. Exemplarily, both the first and second needles include a cylindrical root and a tapered tip.

[0128] like Figure 18 , Figure 19 and Figure 20As shown, the protrusion 22 includes a first needle and a second needle. The second needle includes a needle and a first hook and a second hook disposed at the head of the needle. The radius of the first hook and the second hook is 0.3~0.6mm. The first needle group and the second needle group are arranged at intervals along the length direction of the connector body 21. For example, the radius of the first hook and the second hook is 0.3mm, 0.4mm, 0.5mm or 0.6mm.

[0129] It should be noted that the first needle includes a cylindrical base and a conical tip. The first needle includes a cylindrical base, a conical tip, and a first hook and a second hook located at the head of the conical tip.

[0130] like Figure 21 , Figure 22 and Figure 23 As shown, the protrusion 22 includes a needle and a cap at the head of the needle. The needle includes a cylindrical root and a tapered tip. The cap design at the head of the tapered tip is mainly to enhance the overall torsional resistance of the ultralight main load-bearing component.

[0131] like Figure 24 , Figure 25 and Figure 26 As shown, the protrusion 22 includes a needle and a first hook and a second hook disposed at the head of the needle. The radius of the first hook and the second hook is 0.3~0.6mm. For example, the radius of the first hook and the second hook is 0.3mm, 0.4mm, 0.5mm or 0.6mm.

[0132] The needle comprises a cylindrical base, a conical tip, and a first hook and a second hook located at the head of the conical tip. The bidirectional hook design at the head of the conical tip is primarily intended to better constrain the knitting yarn in both the circumferential and axial directions, thereby enhancing the overall load-bearing capacity.

[0133] like Figure 2 As shown, the connector body 21 is a variable cross-section cylinder, and a pointed needle is integrally manufactured on the outer surface of the cylinder. The pointed needle can be, for example... Figure 12 The pointed needle shown. (As shown) Figure 3 As shown, the connector body 21 is a variable cross-section cylinder, and a pointed needle is integrally manufactured on the outer surface of the cylinder. The pointed needle can be, for example... Figure 21 The pointed needle shown. (As shown) Figure 4 As shown, the connector body 21 is a cylinder with a uniform cross-section, and a pointed needle is integrally manufactured on the outer surface of the cylinder. The pointed needle can be, for example... Figure 15 The pointed needle shown. (As shown) Figure 5 As shown, the connector body 21 is a cylinder with a uniform cross-section, and a pointed needle is integrally manufactured on the outer surface of the cylinder. The pointed needle can be, for example... Figure 24 The pointed needle shown. (As shown) Figure 6As shown, the connector body 21 is a cylinder with a uniform cross-section, and a pointed needle is integrally manufactured on the outer surface of the cylinder. The pointed needle can be, for example... Figure 18 The pointed needle shown.

[0134] In an optional embodiment, the sum of the lengths of the two connector bodies 21 and the length of the support body 1 satisfy the following relationship:

[0135] 0.1 L ≤ L 1+ L 2≤0.8 L ;

[0136] The lengths of the two connector bodies 21 are respectively L 1 and L 2. The length of support body 1 is L .

[0137] It should be noted that the joint body 21 and the support body 1 can form an optimal stress distribution, avoiding stress concentration problems caused by the joint body 21 being too long or too short.

[0138] In addition, this invention also provides an ultralight main load-bearing component, which is manufactured using a three-dimensional braided ultralight main load-bearing component manufacturing method.

[0139] To evaluate the mechanical properties of ultralight main load-bearing components under extreme environments, a long-term (>1 month) water immersion test was conducted on the three-dimensional braided ultralight main load-bearing components, followed by tensile mechanical property testing after immersion. Takeoff overload and landing impact tests (impact overload >100g) were carried out, as well as mechanical property tests in deep space and near-space extreme environments (-185℃ and -110℃), and their load-bearing capacity and impact overload resistance were effectively evaluated.

[0140] 1. Water immersion test

[0141] River water and seawater immersion tests were designed separately. The prefabricated three-dimensional woven ultralight main load-bearing components were numbered and processed. The test pieces were 400mm long, 25mm in outer diameter, and 3mm thick. There were 6 components in the same batch. Three of them were tested for tensile mechanical properties at room temperature. The other three were immersed in water for one month and then taken out for tensile mechanical property tests. By comparing the tensile failure load of the unimmersed test pieces and the immersed test pieces, the impact of immersion on the mechanical properties of the ultralight main load-bearing components was compared.

[0142] The purpose of this experiment was to verify the effect of water immersion on the resin's moisture absorption rate and its load-bearing capacity. Comparative tests (Table 2) showed that the load-bearing capacity was not affected by water immersion and remained essentially consistent with the load-bearing capacity of the un-immersed specimens. This further demonstrates that the three-dimensional braided ultralight main load-bearing component design meets the requirements of underwater engineering applications.

[0143] Table 2 Comparison of test results between water immersion and non-water immersion tests

[0144]

[0145] 2. Takeoff overload and landing impact tests

[0146] Separate tests were designed to conduct takeoff overload impact tests on the three-dimensional woven carbon fiber pod system composed of ultralight main load-bearing components. The pod system was weighed with 100kg and 300kg respectively. During the test, one of the ropes was cut, causing it to fall to a certain height and generate instantaneous impact overload. An acceleration sensor was placed in the middle of the bottom of the pod to measure the impact acceleration value over time and obtain the impact acceleration-time curve. Under the condition of 300kg counterweight, the maximum peak acceleration value was 119g. After the test, a detailed inspection of the three-dimensional woven carbon fiber pod system revealed no damage. The overall structure remained intact and met the requirements of engineering applications.

[0147] In addition, a landing impact test was conducted on the three-dimensional woven carbon fiber pod system composed of ultralight main load-bearing components. The three-dimensional woven carbon fiber pod has an overall counterweight of 300 kg and was dropped from a height of 1.5 m to implement a landing impact. Its maximum impact peak overload reached 208 g. The overall structure of the three-dimensional woven carbon fiber pod system remained intact. The results show that it can meet the impact resistance requirements of resisting instantaneous impact overloads of more than 200 g, and meets the requirements of ultralight, high strength and toughness impact resistance mechanical properties.

[0148] 3. Fatigue performance test

[0149] Considering the long-term service characteristics of near-space airships, fatigue performance tests were also conducted on ultra-lightweight main load-bearing components. The test results showed that their fatigue service life was greater than 1 million cycles (Table 3), and the samples remained intact, meeting the fatigue reliability engineering requirements for ultra-long-term service.

[0150] Table 3. Fatigue Test Data Analysis of Three-Dimensional Braided Ultralight Main Load-Bearing Components

[0151]

[0152] 4. Extreme Environment Ultra-Low Temperature Testing and Thermo-Coupling Simulation

[0153] Mechanical performance tests of ultralight main load-bearing components under extreme environmental ultra-low temperature (-185℃ and -110℃) were designed. The prefabricated ultralight main load-bearing components were numbered. The effective length of the test piece was 200mm (320mm including the clamping section), the outer diameter was 30mm, and the wall thickness was 3mm. There were 6 components in the same batch. Three components were tested at ultra-low temperature of -110℃ and three components were tested at ultra-low temperature of -185℃. The effect of ultra-low temperature on the mechanical performance of ultralight main load-bearing components was verified by comparing the tensile failure load under different ultra-low temperature conditions.

[0154] The purpose of this experiment is to verify the effect of ultra-low temperature on the load-bearing capacity of ultra-light main load-bearing components, as well as the reliability and impact of long-term service in extreme environments. Comparative tests show (Table 4) that the load-bearing capacity under ultra-low temperature in extreme environments is better than that under normal temperature, but there is no significant difference in load-bearing capacity at -185℃ and -110℃.

[0155] This also shows that the ultralight main load-bearing component design proposed in the embodiments of the present invention meets the engineering application requirements of ultra-low temperature long-term service in extreme environments.

[0156] Table 4 Comparison of test results for ultra-low temperature load-bearing capacity in extreme environments

[0157]

[0158] In addition, we conducted numerical simulation analysis on the mechanical properties of the three-dimensional braided ultralight main load-bearing component under thermo-mechanical coupling environment, and compared the simulation results with the test results. The error between the predicted results and the test results was within 8%, which meets the requirements of engineering applications. This also shows that the reliability of the ultralight main load-bearing component proposed in this invention has been further verified.

[0159] In addition, a near-space airship actual flight verification test was carried out on the three-dimensional woven carbon fiber pod system composed of ultralight main load-bearing components. The carbon fiber payload pod adopts a frame structure design. The payload pod consists of 8 ultralight main load-bearing components as the main load-bearing components, and the remaining structure uses carbon fiber secondary load-bearing components. The main load-bearing components and secondary load-bearing components are connected by multi-directional studs and multi-port joints and glued to form the overall frame structure. During the ascent, level flight and landing of the near-space airship, it was subjected to conditions such as takeoff overload, extreme environmental temperature changes and landing impact. The payload pod carries a weight of more than 1 ton. The actual flight verification of the above process shows that the three-dimensional woven payload pod meets the requirements of ultralight, high strength and high toughness load-bearing capacity of near-space airships and can meet the equipment application needs of near-space airships.

[0160] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a three-dimensional woven ultralight main load-bearing component, characterized in that, include: The support body, the first TC4 titanium alloy connector, and the second TC4 titanium alloy connector are assembled to form a tubular body. The first and second TC4 titanium alloy connectors are located at opposite ends of the support body. Each of the first and second TC4 titanium alloy connectors includes a connector body. A protrusion is integrally formed on the entire outer surface of the connector body. The connector body is cylindrical, and the angle between the line connecting the centers of the upper and lower end faces of the cylinder and the edge line of the cylinder is α, where α is 0.3~0.7°. At least one of the first and second TC4 titanium alloy connectors further includes a connecting portion, integrally formed on the side of the connector body away from the support body, and adapted to connect with external components. Carbon fiber yarns are woven into the outer surface of the tubular body using a three-dimensional five-directional weaving method to form a carbon fiber yarn braided layer, which covers the protrusion. The outer diameter of the support is D1, the outer diameters of the first TC4 titanium alloy connector and the second TC4 titanium alloy connector are both D2, and the length of the protrusion is D3. D1 is greater than D2, and D3 is greater than the difference between D1 and D2. Multiple sets of protrusions are arranged at intervals along the length of the connector body, and multiple protrusions in each set are arranged at intervals along the circumferential direction of the connector body; wherein, each protrusion in two adjacent sets of protrusions is staggered. The protrusion includes a pointed needle and a needle cap located at the head of the pointed needle; or, The protrusion includes a first needle and a second needle, the length of the first needle being greater than the length of the second needle. The first needle group and the second needle group are spaced apart along the length direction of the connector body; wherein the length of the first needle is twice the length of the second needle, and the length of the first needle is greater than or equal to 1.4 mm; or... The protrusion includes a pointed needle and a first hook and a second hook disposed at the head of the pointed needle, wherein the radius of the first hook and the second hook is 0.3~0.6mm; or, The protrusion includes a first needle and a second needle. The second needle includes a needle and a first hook and a second hook disposed at the head of the needle. The radius of the first hook and the second hook is 0.3~0.6mm. The first needle group and the second needle group are arranged at intervals along the length direction of the connector body.

2. The manufacturing method of the three-dimensional woven ultralight main load-bearing component according to claim 1, characterized in that, The method of weaving carbon fiber yarns onto the outer surface of the tubular body using a three-dimensional five-directional weaving technique includes: Carbon fiber yarns are woven into the outer surfaces of the connecting part, the joint body, and the support body using a three-dimensional five-directional weaving method, wherein the length of the carbon fiber yarn woven layer on the connecting part is 3% to 5% of the length of the connecting part.

3. The manufacturing method of the three-dimensional woven ultralight main load-bearing component according to claim 2, characterized in that, Also includes: Aramid fibers are spirally wound around the carbon fiber yarn braided layer corresponding to the outer surfaces of the first TC4 titanium alloy joint and the second TC4 titanium alloy joint to form a tough protective layer.

4. The manufacturing method of the three-dimensional woven ultralight main load-bearing component according to claim 1, characterized in that, Before assembling the support, the first TC4 titanium alloy connector, and the second TC4 titanium alloy connector, the following steps are also included: The outer surfaces of the first TC4 titanium alloy connector and the second TC4 titanium alloy connector are sandblasted.

5. The method for manufacturing a three-dimensional woven ultralight main load-bearing component according to claim 1, characterized in that, The outer diameter of the connecting part is equal to the outer diameter of the connector body, and longitudinal and transverse recesses are provided on the outer surface of the connecting part; or... The outer diameter of the connecting part is smaller than the outer diameter of the connector body, and an external thread is provided on the outer surface of the connecting part; or... The outer diameter of the connecting part is equal to the outer diameter of the connector body, and the connecting part is provided with internal threads; or... The connecting part is provided with mounting holes; or... The outer surface of the connecting part is provided with a plurality of block-shaped bodies arranged at intervals along the circumferential direction of the connecting part; or... The connecting part is provided with a connecting flange.

6. The method for manufacturing a three-dimensional woven ultralight main load-bearing component according to claim 1, characterized in that, One of the support body and the connector body is provided with a slot, and the other is provided with a pin that mates with the slot. The support body and the connector body are connected and engaged through the slot and the pin.

7. The method for manufacturing a three-dimensional woven ultralight main load-bearing component according to claim 1, characterized in that, The sum of the lengths of the two connector bodies and the length of the support body satisfy the following relationship: 0.1 L ≤ L 1+ L 2≤0.8 L ； The lengths of the two connector bodies are respectively L 1 and L 2. The length of the support body is L .

8. A three-dimensional woven ultralight main load-bearing component, characterized in that, The three-dimensional braided ultralight main load-bearing component is manufactured using the manufacturing method of the three-dimensional braided ultralight main load-bearing component as described in any one of claims 1 to 7.

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